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1
Gratke, Emily D. "Menageries Multiple: An Introduction to Zoological Multiplicity in the Modern American Zoo." Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/scripps_theses/1059.
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American zoological parks have been sites of intense consumer and scholar interest since their origination in the 20th century. Today, zoos reside at a tenacious hub of ideologies, practices, and priorities contributed to by various stakeholder groups. I propose that the foundational cause of this tension is zoological multiplicity: the theory that through human practices and perceptions, animals can embody multiple identities. Via an exploration of zoological multiplicity in American zoos with specific focus on zoo management, zoogoer, and animal activist stakeholder groups, this project proposes the widespread acknowledgment and understanding of zoological multiplicity as a method to improve animal care and global wildlife conservation projects.
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Cerbin, Adriana Cerbin Linda. "In Situ Conservation Through the Eyes of the Zoo Visitor: Examining Visitor Awareness and Support of the North Carolina Zoological Parkâs Participation in In Situ Conservation Projects." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-03272009-144806/.
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Zoo officials have for many years participated in ex situ conservation activities. Recently however, a growing number of zoos have shown an interest in becoming involved with in situ conservation projects. One such zoo is the North Carolina Zoological Park (NCZP) in Asheboro, NC. NCZP officials have committed to several of these projects and are aware of their importance. However, little is known about how visitors regard these activities. The two research questions asked were: 1) Are visitors aware of the NCZPâs involvement in in situ conservation efforts? and 2) Do patronsâ of the NCZP support those efforts? Three hypotheses were identified. These included: H1: visitors with an increased awareness of the zooâs involvement in in situ conservation would provide a greater amount of support for these projects, H2: membership status would not affect a visitorâs level of declared support for in situ conservation, and H3: membership status would affect a visitorâs level of monetary support for in situ conservation. A survey instrument was developed using a cross-sectional design. The survey focused on four key elements including contributions (monetary support), declared support for local and international projects, understanding of in situ conservation, and visitor relationships with the zoo. The survey was conducted on-site at the NCZP in June and July 2007. Tests of statistical significance and measures of association indicated that awareness played a statistically significant role in how much declared support a visitor had for a project, but had little to no role in how much money visitors contributed on an annual basis. Findings also indicated that membership status was not related to declared support and therefore this relationship was not statistically significant. Finally findings indicated that the relationship between membership status and annual monetary contributions was statistically significant. Recommendations for the NCZP were made based on the studyâs findings.
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Haile, James Seymour. "Ancient DNA from sediments and associated remains." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:8012c839-6a9c-47f9-83a6-b4a0f1d23b93.
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This thesis explores the potential of new substrates for ancient DNA studies and addresses novel questions that can now be asked. It also highlights an additional use of ancient DNA extracted from a traditional source.
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Mortimer, Elizabeth R. "Sonic properties of silks." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:687a0e08-41e3-4e6d-85c0-b7ddf12762f1.
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Silks are biomaterials made by spiders and silkworms, evolved for natural functions ranging from protection to predation. The research presented in this Thesis combines principles and methods from engineering, physics and biology to study the material properties of single silk fibres from a biological perspective. In particular, the factors that contribute to the variation in properties of single silk fibres are investigated. The first part of the Thesis focuses on silks made by silkworms. Whether naturally spun or forced reeled, the mechanical properties of these silks are sensitive to a range of environmental and processing conditions, such as humidity, stretching and reeling speed. The research presented in this section contributes to the understanding of how these applied conditions affect silk mechanical properties, which can be understood in terms of silk’s protein structure and biological context. The second section compares both silkworm and spider silk single fibres to other materials in terms of their sonic properties – how the materials propagate sound waves, whether following impact, or propagating vibrations. The results are discussed in the context of the silk’s natural function for impact resistance (silkworm cocoon or spider web) and vibrational signalling (spider silks). The Thesis ends with a discussion of how the presented techniques can be applied to help further our understanding of orb web function through studying spider silks. Overall, this interdisciplinary Thesis contributes to our understanding of the structure-property-function links of these fascinating biomaterials.
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Wright, Alison Elizabeth. "Mating system, sex-specific selection and the evolution of the avian sex chromosomes." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:89079fac-7196-4c15-ac0e-ceae0c4b0264.
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Sex chromosomes experience distinct evolutionary environments, due to their unusual pattern of inheritance, and studies of sex chromosome evolution can shed light on the fundamental evolutionary forces acting across the genome as a whole. Here, I combine genomic and transcriptomic data across a wide range of avian species to explore the evolutionary processes governing sex chromosome evolution. Birds are female heterogametic and therefore it is possible, via comparisons with male heterogametic species, to identify the fundamental factors driving sex chromosome evolution, versus those associated with sex. In this thesis, I uncover a complex mosaic of recombination suppression between the Z and W chromosomes, characterized by repeated and independent divergence of gametologs, together with ongoing genetic exchange. Additionally, I highlight the role of mating system, and interplay between evolutionary forces, in driving coding and expression evolution on the Z and W chromosomes. My findings indicate that although the Z chromosome is masculinized for male-specific effects, the magnitude of genetic drift acting on Z-linked genes is elevated in promiscuous relative to monogamous mating systems. In contrast, evolution of the female-limited W chromosome is governed predominately by purifying selection. Together, my results suggest that the role of the Z chromosome in encoding sexual dimorphisms may be limited, but that W-linked genes play a significant role in female-specific fitness. In conclusion, my findings reveal the power of mating system in shaping broad patterns of genome evolution.
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Grauf, Coronula. "Brutaktivität und Verhalten der Kiwis (Apteryx mantelli) im Zoo Berlin." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4370/.
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Der Streifenkiwi (Apteryx mantelli) kommt im Freiland nur auf der Nordinsel Neuseelands vor. Aufgrund des gefährdeten Bestands ist eine sich selbst erhaltene Zoopopulation wichtig. Kenntnisse des Verhaltens helfen, die Ansprüche der Tiere zu verstehen. Zudem können sie darüber Auskunft geben, inwiefern das Wohlbefinden eines Tieres gegeben ist.
Durch die Untersuchung der Brutaktivität sollte ein Überblick über den allgemeinen Verlauf der Brut gegeben und Aktivitätsmuster für den Berliner Hahn erarbeitet werden, um den Verlauf zukünftiger Bruten einschätzen und eventuell positiv beeinflussen zu können. Dazu kamen die Untersuchung der täglichen Aktivität einer Henne sowie Beobachtungen des Verhaltens der Tiere. Diese dienten der Bestandsaufnahme der gezeigten Verhaltensweisen und sollten zusammen mit der Aktivität die Grundlage zur Einschätzung bilden, ob die Ansprüche der Kiwis im Zoo Berlin erfüllt werden, und Hinweise zur Verbesserung der Haltung geben.
Die Brutaktivität des Hahnes konnte über drei Brutperioden hinweg detailliert dargestellt werden und zeigte, dass nicht nur innerhalb der Art sondern bei einem einzigen Tier unter ähnlichen Bedingungen die Variabilität so groß sein kann, dass sie für Vorhersagen über den Erfolg einer Brut nicht geeignet ist. Im Zusammenhang mit der Aktivität der Henne ließen sich keine Auffälligkeiten erkennen, die auf eine allgemeine Störung der Tiere schließen lassen oder für eine Beeinträchtigung der Brut verantwortlich gemacht werden könnten.
Soweit aus den Beobachtungen im Freiland geschlossen werden kann, scheinen die Kiwis im Zoo ein weitgehend natürliches Verhalten zu zeigen. Die Haltungsbedingungen scheinen den Ansprüchen der Tiere zu entsprechen.
Es ließen sich nur bedingt Strategien entwickeln, um die Bedingungen für die Brut und damit für die Nachzucht zu verbessern, da sich die Aktivität des Hahnes während der Brut von Jahr zu Jahr als unerwartet variabel erwies. Für ein weiteres Verständnis des Brutverhaltens und eine mögliche Verbesserung der Bedingungen wäre eine Untersuchung zum Einfluss verschiedener Umweltfaktoren auf die Brutaktivität des Hahnes wünschenswert.The North Island brown kiwi (Apteryx mantelli) is an endemic inhabitant of New Zealand's North Island. A self-preserving population at the zoos is important because of endangerment in the wild. Knowledge about their behaviour can help to understand the animal's requirements. Additionally it can provide information on the extent to which their well-being is given in captivity. Observing the breeding activity should lead to an overview of the brood's characteristics and the male's activity pattern in order to assess future broods and possibly influence them in a positive way. Additional observations about the female's daily activity and the male's and female's behaviour were conducted. This led to an inventory of their behavioural patterns. Together with the activity data, this provided a basis for assessing the well-being of the kiwis at Berlin Zoo and to optimize the keeping conditions. The male's breeding activity was described in detail for three breeding periods. It was shown that the variability was very high under similar conditions, so predictions about the breeding success were feasible. In conjunction with the female's activity there were no indications implying an overall disturbance negatively influencing the animals or their breeding. As far as it is known from observations in the wild, kiwis at the zoo seem to widely display natural behavioural patterns. The keeping conditions appear to meet the animal's demands. There were only few strategies that could be developed for further optimization of the breeding conditions because of the high variability of the male's activity. For a deeper understanding of the breeding behaviour and possible improvement of the breeding and keeping conditions, additional research about the activity's dependency on environmental factors would be desirable.
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Flack, Andrea. "Collective decision-making in homing pigeon navigation." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:55ca08f4-404d-4897-ac80-5c832f984c24.
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This thesis focuses on conflict resolution and collective decision-making in co-navigating pigeons, Columba livia. These birds have a remarkable homing ability and frequently fly in flocks. Group navigation demands that group members reach consensus on which path to follow, but the mechanisms by which they do so remain largely unexplored. Pigeons are particularly suitable for studying these mechanisms, due to their sociality and the fact that their possession of information can easily be altered and quantified. I present the results of a series of experiments that manipulated the experience of homing pigeons in various ways so as to observe the effect of information they had previously gathered on their group behaviour. Key findings were: Previous navigational experience contributes to the establishment of leader-follower relationships. The larger the difference in experience between two co-navigating pigeons, the higher the likelihood the more experienced bird will emerge as leader. Shared homing experience through repeated joint flights can allow two pigeons to develop into a “behavioural unit”. They form spatial sub-groups when flying with less familiar birds, and perform a similar transition between compromise- and leadership-dominated flights as single birds, although they are more likely to accept compromise routes. Such previous association histories between birds can thus affect collective decision-making in larger flocks. There is a trade-off between the amount of spatial information handled and the efficiency with which such information can be applied during homing. Leading/following behaviour is influenced by the recency of the route memories. Leadership hierarchies in pigeon flocks appear resistant to changes in the navigational knowledge of a subset of their members, at least when these changes are relatively small in magnitude. The stability of the hierarchical structure might be beneficial during decision-making. Mathematical modelling suggests that underlying hierarchical social structures can increase navigational accuracy. Hierarchically organised groups with the smallest number of strong connections achieve highest accuracy. Group leader-follower dynamics resemble the underlying social structure.
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Blankenburg, Stefanie. "Charakterisierung der GABAB-Rezeptor Subtypen 1 und 2 der Amerikanischen Großschabe Periplaneta americana." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/6964/.
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Die nichtproteinogene Aminosäure GABA (γ-Aminobuttersäure) gilt als der wichtigste inhibitorische Neurotransmitter im Zentralnervensystem von Vertebraten sowie Invertebraten und vermittelt ihre Wirkung u. a. über die metabotropen GABAB-Rezeptoren. Bisher sind diese Rezeptoren bei Insekten nur rudimentär untersucht. Für die Amerikanische Großschabe als etablierter Modellorganismus konnte pharmakologisch eine modulatorische Rolle der GABAB-Rezeptoren bei der Bildung von Primärspeichel nachgewiesen werden. Ziel dieser Arbeit war eine umfassende Charakterisierung der GABAB-Rezeptor-Subtypen 1 und 2 von Periplaneta americana.
Unter Verwendung verschiedenster Klonierungsstrategien sowie der Kooperationsmöglichkeit mit der Arbeitsgruppe von Prof. Dr. T. Miura (Hokkaido, Japan) in Hinsicht auf eine dort etablierte P. americana EST-Datenbank gelang die Klonierung von zwei Rezeptor-cDNAs. Die Analyse der abgeleiteten Aminosäuresequenzen auf GB-spezifische Domänen und konservierte Aminosäure-Reste, sowie der Vergleich zu bekannten GB Sequenzen anderer Arten legen nahe, dass es sich bei den isolierten Sequenzen um die GABAB-Rezeptor-Subtypen 1 und 2 (PeaGB1 und PeaGB2) handelt. Für die funktionelle und pharmakologische Charakterisierung des Heteromers aus PeaGB1 und PeaGB2 wurden Expressionskonstrukte für die Transfektion in HEK-flpTM-Zellen hergestellt. Das Heteromer aus PeaGB1 und PeaGB2 hemmt bei steigenden GABA-Konzentrationen die cAMP-Produktion. Die Substanzen SKF97541 und 3-APPA konnten als Agonisten identifiziert werden. CGP55845 und CGP54626 wirken als vollwertige Antagonisten. Das in vitro ermittelte pharmakologische Profil im Vergleich zur Pharmakologie an der isolierten Drüse bestätigt, dass die GABA-Wirkung in der Speicheldrüse tatsächlich von GBs vermittelt wird. Für die immunhistochemische Charakterisierung konnte ein spezifischer polyklonaler Antikörper gegen die extrazelluläre Schleife 2 des PeaGB1 generiert werden. Ein weiterer Antikörper, welcher gegen den PeaGB2 gerichtet ist, erwies sich hingegen nicht als ausreichend spezifisch. Western-Blot-Analysen bestätigen das Vorkommen beider Subtypen im Zentralnervensystem von P. americana. Zudem wird der PeaGB1 in der Speicheldrüse und in den Geschlechtsdrüsen der Schabenmännchen exprimiert. Immunhistochemische Analysen zeigen eine PeaGB1-ähnliche Markierung in den GABAergen Fasern der Speicheldrüse auf. Demnach fungiert der PeaGB1 hier als Autorezeptor. Weiterhin konnte eine PeaGB1-ähnliche Markierung in nahezu allen Gehirnneuropilen festgestellt werden. Auch die akzessorischen Drüsen der Männchen, Pilzdrüse und Phallusdrüse, sind PeaGB1-immunreaktiv.The non-proteinogenic amino acid GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the central nervous system of vertebrates and invertebrates, and GABA mediates its action among others via metabotropic GABAB receptors (GBs). So far, these receptors are only rudimentary characterized in insects. In the American Cockroach, which is an established model organism, pharmacological studies have pointed out a modulatory role of GBs in the production of primary saliva in the salivary gland. Therefore, the aim of this study is the profound characterization of the GABAB receptor subtypes 1 and 2 of Periplaneta americana. Diverse cloning strategies and the access to a Periplaneta EST-database enabled the cloning of two receptor-cDNAs. The analysis of the deduced amino acid sequences for GB-specific domains and conserved amino acid-residues, and the comparison to known GB-sequences of other species revealed that the sequences correspond to GABAB receptor subtypes 1 and 2 (PeaGB1 and PeaGB2). Next, we functionally and pharmacologically characterized the receptor-heteromer of PeaGB1 and PeaGB2. Therefore, we established expression constructs for the transfection of HEK-flpTM-cells. The PeaGB1/PeaGB2 heteromer inhibits dose-dependently the production of cAMP. The substances SKF97541 and 3-APPA imitate the GABA effect. In contrast, CGP54626 and CGP55845 are considered to be proper antagonists. The comparison of the in vitro with the known pharmacology of isolated glands reveals that GBs indeed mediate the effect of GABA in the salivary gland. For immunohistochemical localization, a specific polyclonal antibody was raised against the extracellular loop 2 of PeaGB1. A second antibody, which was raised against the analogous region of the PeaGB2, must be considered to be non-specific. Western blot analyses demonstrate the localization of both subtypes in the central nervous system of P. americana. Additionally, PeaGB1 is expressed in the salivary gland and in male accessory glands. Immunohistochemical analyses reveal the expression of PeaGB1 in GABAergic nerve fibers of the salivary gland. As a consequence, PeaGB1 must act as an autoreceptor in this organ. A widespread distribution of PeaGB1 in almost all neuropiles was detected in the cockroach brain. In the male accessory glands mushroom gland and phallic (conglobate) gland, an intense PeaGB1-like immunoreactivity was measured.
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Braczkowski, Aleksander Ryszard. "The susceptibility of leopards Panthera pardus to trophy hunting : the trophy hunting of leopards." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:801c0746-1b25-4c84-9ce8-bfeaf6c014d3.
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The trophy hunting of African leopards Panthera pardus pardus may generate revenue to help foster their conservation. However, leopards are sensitive to hunting and populations decline if overharvested. The practice therefore requires careful management grounded in robust estimates of population density/status. Camera-trap surveys are commonly used to establish leopard numbers, and may guide harvest quotas. However, such surveys are limited over wide spatial scales and many African governments lack resources to implement them. In this thesis I explore the potential use of a harvest composition scheme applied to puma Puma concolor in North America, to monitor leopards. The method hinges on the susceptibility of different leopard cohorts to hunting and if this varies, then predictions can be made about harvest composition. Susceptibility is likely to be governed by space use, encounter rates with bait lures (a common method used to attract leopards to hunting hides) and hunter selectivity. Thus in this thesis I explore leopard susceptibility to these factors using a protected leopard population in northern Zululand, South Africa. In my first chapter I examine using scent lures in camera-trapping. Against a backdrop of a passive survey I show adult males, females and sub-adults are captured at similar rates compared to a passive survey using lures. The use of lures does not appear to violate closure assumptions or affect spatio-temporal patterning, but their use appears limited as density estimate precision is not improved. My second chapter examines ecological (likelihood of encountering a hunter) and anthropogenic (attractiveness to hunters) susceptibility of leopards to trophy hunting. I show that adult males are the most susceptible cohort to hunting (sub-adults least susceptible). I then take the incident rates from ecological and anthropogenic models and create a theoretical harvest composition using population parameters of protected leopards. My third data chapter departs from hunting susceptibility and examines determinants of leopard trophy package price across Africa. I show that factors such as trophy quality, outfitter leopard hunting reputation and hunt success have little impact on price determination. Instead, overall outfitter reputation and the number of charismatic species in a package are positively correlated with price. These results have important consequences on several sustainable leopard hunting schemes proposed in the literature.
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Wyres, Kelly L. "Genome evolution in Streptococcus pneumoniae." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:985b1fc6-c1a9-41b3-a20a-1735329d962b.
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Streptococcus pneumoniae (the pneumococcus) is a bacterial pathogen responsible for >1.6 million annual deaths globally. Pneumococcal penicillin-resistance is conferred by acquisition of ‘altered’ penicillin-binding protein (pbp) genes. The first penicillin-nonsusceptible pneumococci were identified in the late 1960s. Global pneumococcal penicillin-nonsusceptibility rates rapidly increased in the 1980s/90s. Since 2000, protein-conjugate vaccines, targeting 7, 10 or 13 of the ≥94 different pneumococcal capsule types (serotypes), have been introduced in many countries. Following vaccine implementation there has been a decline in vaccine-type pneumococcal disease and an increase in non-vaccine-type disease. These epidemiological changes result from “serotype replacement” and/or “serotype switching”. The former describes the expansion of non-vaccine-type clones in the absence of vaccine-type pneumococci. The latter describes serotype change following recombination at the capsule polysaccharide synthesis (cps) locus. To fully understand how pneumococci respond to vaccine- and antibiotic-induced selective pressures, we must better understand the evolutionary history of this pathogen. This thesis describes the study of a global collection of 426 pneumococci, dated 1937 - 2007. Serotype, genotype and penicillin-susceptibility data were collected. Nucleotide sequences of three pbp genes (for 389 isolates) and whole-genome sequences (for 96 isolates) were also generated. The data demonstrated the long-term persistence of certain clones within pneumococcal populations, and that pbp and large-fragment (>30 kb) cps ± pbp recombination was occurring prior to both widespread antibiotic use and vaccine implementation. The data highlighted the promiscuous nature of the globally-distributed PMEN1 clone and its contribution to the spread of pneumococcal penicillin-resistance. PMEN1 also donated multiple, large regions (1.7 - 32.3 kb) of its genome to at least two un-related clones. Finally, six “Tn916-like” genetic elements, conferring resistance to non-penicillin antibiotics, were newly identified. These included two of the oldest ever described. These results provided a unique insight into the history of pneumococcal evolution and the importance of genetic recombination.
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Smith, Amy Elisabeth. "The centriole in evolution : from motility to mitosis." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:f48e77ea-fbf9-4ac6-b86e-854f6739a5aa.
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Centrioles and basal bodies with their characteristic 9+2 structure are found in all major eukaryotic lineages. The correlation between the occurrence of centrioles and the presence of cilia/flagella, but not centrosome-like structures, suggests that the ciliogenesis function of centrioles is ancestral. Here, it is demonstrated that the centriole domain of centrosomes emerged within the Metazoa from an ancestral state of possessing a centriole with basal body function but no functional association with a centrosome. Centrosome structures involving a centriole are metazoan innovations. When an axoneme is still present but no longer fully functional, such as the sensory cilia of Caenorhabditis elegans or, as depicted here, the flagellum of the intracellular amastigote stage of the Leishmania mexicana parasite, the basal body structure is less constrained and can depart from the canonical structure. A general view has emerged that classifies axonemes into canonical motile 9+2 and noncanonical, sensory 9+0 structures. This study reveals this view to be overly simplistic, and additional axonemal architectures associated with potential sensory structures should be incorporated into prevailing models. Here, a striking similarity between the axoneme structure of Leishmania amastigotes and vertebrate primary cilia is revealed. This striking conservation of ciliary structure, despite the evolutionary distance between Leishmania and mammalian cells, suggests a sensory function for the amastigote flagellum. Adding weight to a sensory hypothesis, close examination of Leishmania positioning inside the parasitophorous vacuole revealed frequent contact between the flagellum tip and the vacuole membrane. A sensory function could also explain the retention of a flagellum in Trypanosoma cruzi amastigotes, an intracellular stage that, as shown in this study, emerged independently to the Leishmania amastigote. Basal body appendages, such as pro-basal bodies and microtubule rootlets, also vary widely in their structure. Choanoflagellates, a sister group to the Metazoa, posses an extensive microtubule rootlet system that provides support for their characteristic collar tentacles. This atypical structure is reflected in the underlying molecular components of the choanoflagellate basal body. The importance of choanoflagellates as the closest known relative of metazoans was first revealed by their similarity to choanocytes, the feeding cells of sponges. Although phylogenetic analyses leave little doubt that choanoflagellates are a sister group of animals, comparisons of molecular and structural components of appendages associated with the collar tentacles highlight significant differences and questions the extent to which the collar structures of choanoflagellates and choanocytes can be assumed to be homologous. Finally, the confinement of a centriole-based centrosome to the Metazoa provides little support for the flagellar synthesis constraint as an explanation for the origin of multicellularity. There is, indeed, an apparent constraint; no flagellated or ciliated metazoan cell ever divides. This constraint, however, did not arise until after the incorporation of centrioles into the centrosome in the metazoan lineage and the co-option of centrioles as a structural and functional component of the centrosome. The flagellar synthesis constraint is therefore not an explanation for the origin of multicellularity but a consequence of it.
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Lukasik, Piotr. "The facultative endosymbionts of grain aphids and the horizontal transfer of ecologically important traits." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:6aedd183-2dde-4099-a74a-e3f7c909546a.
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Insects are often infected with facultative endosymbiotic bacteria, which can have a range of important ecological effects. The grain aphid, Sitobion avenae, harbours diverse facultative symbionts, which suggests their importance in grain aphid biology. This thesis attempts to explain the ecological roles of the facultative endosymbionts in S. avenae. It also examines the question of whether the horizontal transmission of symbionts between aphid clones and species can be important for shaping the ecology and evolution of multi-species aphid communities. Novel techniques developed for research with the grain aphid study system are presented. Grain aphid clones vary in their tolerance to low temperatures, but this trait is not affected by their facultative endosymbionts. Strains of a symbiont Hamiltonella defensa do not protect grain aphids from hymenopterous parasitoids, regardless of the host genotype. However, experienced parasitoid females preferentially oviposit in aphids which do not harbour symbionts. Comparison of the fitness consequences of infection with the same Hamiltonella strains in their original and in novel grain aphid host clones reveal no consistent differences. Symbiont strains establish easily following artificial transfer between clones of the grain aphid, but the symbionts transferred from other aphid species form less stable infections. Hamiltonella strains do not affect the fecundity of their grain aphid host clones regardless of their host species of origin, but also do not generally confer protection against parasitoids. There are no clear patterns in the distribution of parasitoid-resistant phenotypes across phylogenetic trees of Hamiltonella and its bacteriophage APSE. Strains of four unrelated species of endosymbionts, Rickettsia, Spiroplasma, Rickettsiella and Regiella, confer the same pathogen-resistant phenotype to a single pea aphid clone. The same symbiont strains can confer resistance to clones of two different aphid species. Some strains in multiple infections may compensate for the costs of infections with other symbionts. The importance of these results for understanding the ecological and evolutionary role of facultative endosymbionts in aphids and other insects are discussed, and directions for further research are proposed.
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Chen, Chong. "Systematics, ecology, and evolution of hydrothermal vent endemic peltospirids (Mollusca: Gastropoda) from the Indian and Southern oceans." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:0136047f-a09b-4876-bb65-b74dfd7c997d.
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This thesis centres around two genera of large peltospirid gastropods (Mollusca: Neomphalina: Peltospiridae) endemic to hydrothermal vent ecosystems. One is the 'scaly-foot gastropod', an emblematic species of the Indian Ocean vents with unique dermal sclerites covering the foot like roof tiles. The other was recently discovered from expeditions to the Southern and Indian oceans, lacks sclerites and possesses large opercula. As both genera and their assigned species remained undescribed, they were formally described herein which forms a basis to understanding their biology. The 'scaly-foot gastropod' from both the Central Indian Ridge (CIR) and the Southwest Indian Ridge (SWIR) were confirmed to represent a single species and is formally named as Chrysomallon squamiferum. Through molecular genetic analyses using the COI gene, genetic differentiation between SWIR and CIR populations was detected for the 'scaly-foot gastropod'. In contrast, the peltospirids with large opercula from the East Scotia Ridge (ESR) and the SWIR proved to be two distinct species within an undescribed genus. The ESR species was formally described as Gigantopelta chessoia and the SWIR species as G. aegis. The molecular genetic analyses of the COI gene, confirmed the genetic isolation of the two and consolidated their status as separate species. A 3D tomographic model of Chrysomallon squamiferum was generated to characterise the soft anatomy and morphology as well as to understand its internal anatomy and adaptation which remained little-studied. Further to the enlarged esophageal gland already known to house chemosynthetic endosymbionts, C. squamiferum was discovered to have a hypertrophied circulatory system with a gigantic, muscular heart and large ctenidium to adapt to life in a hypoxic environment and to supply the endosymbionts with necessary chemicals. Histological examinations of the sclerites and operculum showed that it was unlikely that the sclerites originated from operculum duplication. Comparisons with polyplacophoran scales revealed starkly different secretion mechanisms despite the superficial similarity, which has implications on the placement of sclerite-bearing Cambrian taxa. Overall, the results from this thesis ascertained the systematic positions of these large-sized, enigmatic peltospirids, and led to improved understanding of their ecology and evolution. The important role of larval dispersal in maintaining metapopulations across the distribution of a vent-endemic taxa is highlighted. The adaptations of vent-endemic taxa remains little-known even in well-studied species, warranting future studies on these and other species.
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Voss, Insa. "Die Bedeutung der Paarbindung für das Fortpflanzungspotential von Papageienvögeln (Psittaciformes) : vergleichende Untersuchung zu Hormonstatus und Verhalten." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4159/.
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Zum Erhalt vom Aussterben bedrohter Papageienvögel (Psittaciformes) ist die Nachzucht in Menschenobhut neben dem Erhalt freilebender Populationen von großer Bedeutung, die Reproduktion bestimmter Arten gelingt allerdings nur unzureichend. Als Hauptgrund dafür gilt die Zwangsverpaarung im Rahmen von Zuchtprogrammen (Beispiel: Europäisches Erhaltungszuchtprogramm, EEP), hier werden Brutpaare hauptsächlich nach genetischen Aspekten zusammengestellt. Der reproduktive Erfolg ist bei den meisten Papageienarten, die in dauerhaften Paarbindungen leben (perennial monogamy), eng der Paarbindung korreliert. Eine freie Partnerwahl ist demnach von großer Bedeutung für die Zucht in Menschenobhut, im Rahmen von Erhaltungszuchtprogrammen jedoch nur selten möglich.
Das Ziel der Untersuchung war, eine wissenschaftlich begründete Methode zu entwickeln, durch die es möglich sein soll, das Fortpflanzungspotential von Brutpaaren der Gattung Ara anhand der Paarbindung zu bestimmen. Dafür wurde die Bedeutung der Qualität der Paarbindung der Brutpaare für den Lebens-Reproduktionserfolg (Lifetime-reproductive success, LRS) untersucht.
Die Datenaufnahme erfolgte in dem Zuchtzentrum 'La Vera' der Loro Parque Fundación auf Teneriffa/ Spanien. Hier wurden in den Jahren 2006 und 2007 21 Brutpaare der Gattung Ara untersucht. Die Paarbindung wurde zum Einen durch typisches Paarbindungsverhalten und zum Anderen durch die physiologische Abstimmung der einzelnen Brutpaare anhand der Ausschüttung des Steroidhormons Testosteron dargestellt. Das Paarbindungsverhalten setzte sich aus der ‚Abstimmung der Tagesaktivität’, dem ‚Kontaktverhalten’ und den ‚sozialen Interaktionen’ zusammen. Zur Abstimmung der Tagesaktivität zählten die Verhaltensweisen Ruhen, Sitzen, Nahrungsaufnahme, Gefiederpflege, Beschäftigung und Lokomotion. Unter Kontaktverhalten wurden das Überschreiten der Individualdistanz bei bestimmten Verhaltensweisen und die Rollenverteilung der Geschlechter untersucht. Unter ‚sozialen Interaktionen’ wurden die Dauer und der Häufigkeit der sozialen Gefiederpflege und der Sozialen Index zusammengefasst. Bei der sozialen Gefiederpflege wurde die Dauer und die Häufigkeit der Phasen erhoben, sowie der jeweilige Initiator dieser Interaktion. Zusätzlich wurde untersucht, welches Geschlecht, wie häufig und mit welcher Dauer aktiv an der sozialen Gefiederpflege beteiligt war. Aus den Beobachtungen wurde der soziale Index berechnet, der angibt, wie das Verhältnis sozio-positiver zu agonistischen Interaktionen für jedes Individuum, sowie das Paar an sich ist.
Zur Messung der Testosteron-Ausschüttung der Partnertiere wurden von September bis November 2007 über einen Zeitraum von 9 Wochen jede Woche einmal für jedes Individuum Kotproben gesammelt. Mit der Analyse der Proben wurde das Veterinär-Physiologisch-Chemische-Institut der Universität Leipzig unter der Leitung von Prof. Dr. Almuth Einspanier beauftragt. Zur Ermittlung des Hormongehalts in den gewonnenen Kotproben diente ein kompetitiver Doppelantikörper-Enzymimmunoassay (EIA). Das Fortpflanzungspotential wurde über die Anzahl der Eier, Gelege und Jungtiere, sowie über die Gelegegröße dargestellt. Diese Daten geben, bezogen auf die Dauer der Paarbindung, Auskunft über die Produktivität eines Brutpaares, anhand dessen zusätzlich ein Produktivitäts-Koeffizient berechnet wurde. Des weiteren sollte die Anzahl der von einem Brutpaar selbständig großgezogenen Jungtiere Auskunft über die Fähigkeit zur kooperativen Jungenaufzucht geben. Zur Untersuchung der Bedeutung der Paarbindungsqualität wurden Diskriminanzfunktionsanalysen und Regressionsanalysen durchgeführt, wozu die untersuchten Brutpaare anhand ihres Fortpflanzungspotentials in verschiedene Gruppen eingeteilt wurden. Anhand der Ergebnisse der Studie konnte gezeigt werden, dass das Fortpflanzungspotential von Brutpaaren von verschiedenen Kriterien, die die Paarbindungsqualität charakterisieren, abhängt. Dabei ist zwischen der Produktivität und der Fähigkeit zur kooperativen Jungenaufzucht zu unterscheiden. Die Produktivität eines Paares wurde hinsichtlich der abgestimmten Tagesaktivität positiv vom synchronen Ruhen mit dem Partner beeinflusst, sowie von der Häufigkeit und Dauer der vom Weibchen ausgehenden sozialen Gefiederpflege. Brutpaare mit hoher Produktivität waren zudem über eine hohe ‚intra-Paar Fluktuation’ des Steroidhormons Testosteron gekennzeichnet. Die Brutpaare, die in der Lage sind, ihre Jungtiere in Kooperation großzuziehen, zeigten ebenfalls einen hohen Anteil zeitlich mit dem Partner abgestimmter Ruhephasen, zudem häufiges Ruheverhalten in Körperkontakt zum Partner und ein hohes zeitliches Investment der Männchen bei der Initiierung und Durchführung sozialer Gefiederpflege. Darüber hinaus zeigten Männchen, die einen Beitrag zur kooperativen Jungenaufzucht leisten, eine wesentlich geringere durchschnittliche Testosteron-Konzentration – bezogen auf den Untersuchungszeitraum, als Männchen, die Brutpaaren angehören, die nicht zur selbständigen Jungenaufzucht fähig sind. Dieses Ergebnis spiegelt die Bedeutung von Testosteron bei der elterlichen Fürsorge wider und bietet einen Anhaltspunkt für weitere Untersuchungen. Die Untersuchung konnte zeigen, dass es möglich und sinnvoll ist, das individuelle Verhalten von Tieren in Menschenobhut für den Erhalt bedrohter Tierarten einzusetzen. Weitere, auf dieser Studie aufbauende Untersuchungen sollten zum Ziel haben, zuverlässig die Brutpaare erkennbar zu machen, die über ein gutes Fortpflanzungspotential verfügen. Auf diese Weise kann unzureichender Reproduktionserfolg bedrohter Papageienarten in Menschenobhut infolge von Zwangsverpaarung minimiert werden.In addition to preserve wild populations, captive breeding of certain species is important for the conservation of endangered parrots (Psittaciformes). However, captive breeding of parrot species is rarely successful. The main reason for this failure is that forced pairings are applied under the context of breeding programs such as European Endangered Species Program, EEP, in which breeding pairs are primarily selected under genetic aspects. Bond quality affects the reproductive success of most perennial monogamous parrot species significantly. A free mate selection is therefore important for successful breeding in captivity; however, it is hard to achieve as a part of conservation breeding programs. The aim of this study is to develop a scientific method to determine the reproductive potential of breeding pairs of the genus Ara based on the pair bond. Therefore, the relationship of the pair bond quality in breeding pairs for lifetime reproductive success (LRS) is investigated in this study. The data of 21 breeding pairs was collected in the breeding facility 'La Vera' of the Loro Parque Fundación in Tenerife, Spain between 2006 and 2007. The pair bond was characterized firstly by the typical pair bonding behaviour and secondly by the physiological adaptation of each breeding pair based on the steroid hormone testosterone releases. The pair bonding behaviour consisted in ‘daily activity', ‘contact behaviour' and 'social interactions'. The ‘daily activity' included the behaviours: resting, sitting, eating, preening, activity and movement. Certain individual behaviours and gender roles were examined for the ‘contact behaviour'. The duration and frequency of social preening and the social index were summarized as 'social interactions'. In the social preening the duration and frequency of the phases was recorded, and the respective initiator of this interaction. In addition, gender of the individual, frequency, and duration of the social preening was recorded. Furthermore the social index was calculated, which indicates the relationship between agonistic and socio-positive interactions. To measure the testosterone release in the pair members over 9 weeks (September to November 2007), faecal samples were collected from each individual once a week. The faecal samples were analyzed at the Institute for Physiological Chemistry at the University of Leipzig under supervision of Prof. Dr. Almuth Einspanier. Competitive double-Antibody Enzyme Immunoassay (EIA) was applied to determine the testosteronecontent of the faecal samples. Reproductive success was represented by number of eggs, nests and chicks, and the clutch size. These data provide, based on the duration of the pair bond, information about the productivity of breeding pairs. Furthermore, the number of chicks reared by one breeding pair independently should provide information about the capacity for cooperative breeding. Breeding pairs were classified into different groups depending on their reproductive potential. This classification was verified by discriminant analysis and regression analysis to investigate the importance of the quality of the pair bond for reproductive success. I found that the reproductive potential of breeding pairs is related to various criteria that characterize the quality of a pair bond, but it is essential to distinguish between the productivity itself and the ability to cooperative breeding. The synchronous resting with a partner according to the daily activity, as well as the frequency and duration of social preening initiated by the female positively influenced the productivity of a pair. Breeding pairs with high productivity also showed a high ‚intra-pair fluctuation' of the steroid hormone testosterone level. The breeding pairs which are able to raise their young in cooperation also showed a high percentage of time with coordinated phases of resting, also frequent resting behaviour in physical contact with the partner and a high investment of males in the initiation and implementation of social preening. In addition, males, which actively contribute to cooperative breeding, showed significantly lower testosterone concentrations than males, which were members of breeding pairs not capable of raising chicks on its own. This result emphasizes the importance of testosterone during the parental care, especially in males, and provides a starting point for further investigations. My investigation shows that it is possible and useful to apply the individual behaviour of animals in captivity for the conservation of endangered species. Based on this study, further research should be aimed to expose reliable breeding pairs with good reproductive potential, by behaviour and by measuring hormonal states. In this way, poor reproductive success of endangered parrot species in captivity as a result of forced parings can be minimized.
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Hapairai, Limb K. M. "Studies on Aedes polynesiensis introgression and ecology to facilitate lymphatic filariasis control." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:8bc43695-4394-4a56-b83d-0a5ffe2dbebd.
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The mosquito Aedes polynesiensis, a member of the Aedes scutellaris complex, is the main vector in the South Pacific region of the Wuchereria bancrofti parasite, the causative agent of lymphatic filariasis (LF), and is also a major nuisance biter. Decades of Mass Drug treatment (MDA) have not been successful in elimination LF. Two non-vector species in the Ae. scutellaris complex were introgressed with Ae. polynesiensis to attempt to obtain lines that would produce cytoplasmic incompatibility (CI) with wild populations and/or LF-refractoriness. Despite selection of progeny from Brugia-challenged, non-infective females at each backcross, no refractory line was acquired. However, three lines from crosses between aposymbiotic Ae. polynesiensis and Ae. riversi displayed CI and male mating competiveness suitable for the purpose of population suppression using the incompatible insect technique (IIT). A population study was conducted of potential release sites and the evaluation of monitoring tools for Ae. polynesiensis on Moorea and Tetiaroa, French Polynesia. There was no evidence of active migration between selected islets on the atoll of Tetiaroa, suggesting it is a suitable site for field releases of CI males. The BioGents Sentinel trap was shown to be an efficient and convenient trap suitable for Ae. polynesiensis monitoring. The effects of temperature and larval density on life-table parameters relevant to IIT were examined, including: larval survivorship, developmental time to pupation, male to female ratio, male pupae yield, male size and adult male survival. These findings were used to design and conduct a 14-week field experiment testing CI male strain against an isolated population, using optimized rearing conditions. Approximately 8000 males were released weekly on motu Onetahi, Tetiaroa atoll. Significant sterility was induced by Wolbachia in the targeted female population, supporting the development and scale-up of this approach toward Ae. polynesiensis nuisance and LF transmission reduction.
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Leggett, Helen Catherine. "Developments in social evolution and virulence in parasites." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e69b69ae-440a-4d32-8947-efb4a0c55930.
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The study of social evolution and virulence in parasites is concerned with fitness consequences of trade-offs between parasite life history traits and interactions between parasite species and/or genotypes with their hosts. I develop our understanding of social evolution and virulence in parasites in several ways. (1) I review empirical evidence for the fundamental predictions of virulence-transmission trade-off theory and demonstrate that the fit between theory and data is primarily qualitative rather than quantitative; that parasites differ in their degree of host generalism, and this is likely to impact virulence in four ways. (2) I take a comparative approach to examine the underlying causes of an observed statistical variation in the size of parasite infectious doses across taxa, revealing that mechanisms used by parasites to infect hosts are able to explain variation in both infectious dose and virulence. (3) I formally compare data on human pathogens to explain variation in virulence across taxa, revealing that immune subversion and not growth rate, explains variation in virulence. This allows me to predict that immune subverters and not fast growing parasites are likely to cause the most virulent clinical infections. (4) Using bacteria and their naturally infecting viruses (bacteriophage), I take an experimental approach to investigate the consequences of coinfection for parasite life history traits, and find that viruses cultured under a mix of single infections and coinfections evolved plasticity; they killed hosts more rapidly when coinfecting, and this resulted in high fitness under both single infection and coinfection conditions. (5) I experimentally investigate how selection within and between hosts and patches of hosts affects the fitness and virulence of populations of these viruses. I find that limited host availability favours virulent, faster killing parasites with reduced transmission; suggesting high, rather than low, virulence may be common in spatially structured host-parasite communities.
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Parker, Joseph David. "The within- and among-host evolution of chronically-infecting human RNA viruses." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:4ff0458d-ccd4-48c3-ad7c-1bcf724f8a4a.
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This thesis examines the evolutionary biology of the RNA viruses, a diverse group of pathogens that cause significant diseases. The focus of this work is the relationship between the processes driving the evolution of virus populations within individual hosts and at the epidemic level. First, Chapter One reviews the basic biology of RNA viruses, the current state of knowledge in relevant topics of evolutionary virology, and the principles that underlie the most commonly used methods in this thesis. In Chapter Two, I develop and test a novel framework to estimate the significance of phylogeny-trait association in viral phylogenies. The method incorporates phylogenetic uncertainty through the use of posterior sets of trees (PST) produced in Bayesian MCMC analyses. In Chapter Three, I conduct a comprehensive analysis of the substitution rate of hepatitis C virus (HCV) in within- and between-host data sets using a relaxed molecular clock. I find that within-host substitution rates are more rapid than previously appreciated, that heterotachy is rife in within-host data sets, and that selection is likely to be a primary driver. In Chapter Four I apply the techniques developed in Chapter Two to successfully detect compartmentalization between peripheral blood and cervical tissues in a large data set of human immunodeficiency virus (HIV) patients. I propose that compartmentalization in the cervix is maintained by selection. I extend the framework developed in Chapter Two in Chapter Five and explore the Type II error of the statistics used. In Chapter Six I review the findings of this thesis and conclude with a general discussion of the relationship between within- and among-host evolution in viruses, and some of the limitations of current techniques.
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Bilski, Michal Mamert. "Engineered genetic sterility of pest insects." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:0d2bc7dd-7388-4418-a614-c7d77d8c905d.
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In the light of increasing pesticides resistance in agricultural pests and in insect vectors of human diseases, leading to the rise in occurrence of mosquito-borne diseases, new, efficient and environmentally friendly methods of pest control are needed. Sterile Insect Technique (SIT), relying on mass releases of radiation sterilised males to reduce reproductive potential of target pest populations, although not new, offers an alternative to the use of pesticides and is an environmentally non-polluting method of insect control. Many insect species, however, are not very amenable to classical SIT, due to detrimental side-effects of radiation treatment. We propose a new method, a genetically engineered modification of classical SIT, replacing radiation with genetically induced sterility. Based on conditional expression of male-germline targeted nucleases which introduce double strand breaks into the male germline DNA to render males sterile, this method emulates SIT mechanism, at the same time eliminating radiation and associated detrimental side-effects. Different variants of such a system were investigated in this project, eventually leading to the creation of functional conditional male-sterility systems in two model organisms – the Yellow fever mosquito, Aedes aegypti and the Mediterranean fruit fly, Ceratitis capitata. Both systems utilise chimeric nuclease composed of protamine and FokI cleavage domain fusion. The sperm-specificity and the conditionality of the sterile phenotype have been achieved through the use of tetracycline repressible expression system driven by the β2-tubulin promoter in Ceratitis capitata and by the Topi promoter in Aedes aegypti.
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Ant, Thomas. "Genetic control of the olive fruit fly, Bactrocera oleae." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:43f97545-f631-43cc-991c-7edb6dd71d2d.
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The olive fruit fly, Bactrocera oleae, (Rossi) (Diptera:Tephritidae), is a key pest of olive crops. The sterile insect technique (SIT) is an environmentally benign and species-specific method of pest control, aiming to reduce the reproductive potential of a wild population through the mass-release of sterile insects. Previous olive fly SIT trials, involving the release of gamma-ray sterilised mixed-sex populations, achieved limited success. Key problems included altered diurnal mating rhythms of the laboratory-reared insects, leading to assortative mating between released and wild populations, and low competitiveness of the radiation sterilised mass-reared flies. Consequently, the production of competitive, male-only release cohorts is seen as essential. The RIDL (Release of Insects carrying a Dominant Lethal) system is a transgene-based derivative of SIT, one version of which involves the mass release of insects carrying a female specific lethal transgene (fsRIDL). This thesis describes: 1) the development of fsRIDL olive fly strains and the molecular analysis of transgene insertion and function; 2) the analysis of strain life-history parameters; 3) studies into sexual selection and mating compatibility; 4) a caged proof-of-principle population suppression trial; and, 5) selection dynamics on the fsRIDL trait in caged populations. Olive fly fsRIDL strains were developed with full female-lethal penetrance and repressibility. The lead strain displayed similar life-history and sexual competitiveness traits to those of the wild-type strain from which they were derived. In addition, transgenic males showed photoperiod compatibility and strong sexual competitiveness with field-collected wild olive flies. The feasibility of the fsRIDL approach was demonstrated when repeated male releases caused eradication of caged olive fly populations. Although needing field confirmation, these results suggest that fsRIDL olive fly strains may help to mitigate key problems experienced in previous olive fly SIT trials, and could help form the basis of a renewed effort towards olive fly SIT control.
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Wonders, Karen. "Habitat dioramas : illusions of wilderness in museums of natural history /." Stockholm : Almqvist och Wiksell, 1993. http://catalogue.bnf.fr/ark:/12148/cb35614492v.
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Gratwicke, Brian. "Factors affecting fish distribution in coastal habitats of the British Virgin Islands." Thesis, University of Oxford, 2004. http://ora.ox.ac.uk/objects/uuid:f0b83565-7ed9-4612-ac98-b203b19a8be5.
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Few studies of tropical fish communities compare fish distributions across the full range of near-shore tropical marine habitats. As a result, our understanding of tropical marine fish communities is often biased towards habitats preferred by researchers. The distribution and habitat preferences of all 136 fish species occurring at 106 stations in three bays off Tortola in the British Virgin Islands were assessed. At a species level, habitat type was often the key factor influencing fish distribution. Of the 44 species occurring at more than 10 stations, 3 were sand specialists, 5 were strongly associated with mangroves, 7 were dependent on seagrass and algal beds and 14 were found only on the forereef. Eleven species were widely distributed both on the forereef and in bays, and 9 of them showed clear evidence of ontogenetic partitioning. The juveniles all preferred bay habitat types and moved onto the forereef as they approached sexual maturity. At a community level, five distinct fish assemblages were found. The assemblage types were classified according to their distribution: 1) forereef, 2) reef flat, 3) non-mangrove associated seagrass, 4) mangrove associated seagrass and 5) eutrophic areas. Forereef stations were the most species-rich with 24 species per station while eutrophic stations had the most depauperate communities with only 4 species per station. Variation in fish species richness at each station was largely explained by a simple habitat complexity index. It accounted for 70% of the variation in fish species richness and 21% of the variation in fish abundance. Rugosity and variety of growth forms were the most important predictors of species richness, but the height of the habitat architecture was the most useful predictor of fish abundance. Artificial reefs were constructed to test the effects of each habitat complexity variable experimentally. Increasing rugosity, variety of growth forms and percentage hard substrate increased the observed number of species but increasing the variety of hole-sizes, and height had no effect. The only complexity variable that had a significant effect on fish abundance was percentage hard substrate. In addition to the static substrate structure, long-spined sea urchins Diadema antillarum affected fish distribution because small fish shelter from predators in their spines. The urchins increase species richness and abundance in low complexity seagrass beds, but on artificial reefs, where shelter was not a limiting factor, the effect was less pronounced. Organic pollution is another factor that negatively affects the fish community by reducing fish species richness and abundance. Poor water quality often alters the natural habitat, confounding observations, but fish species richness was reduced in polluted areas even when artificial reefs were used as habitat controls. The applications of these findings to the management and conservation of fish in the British Virgin Islands are discussed.
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Itonaga, Naomi. "White storks (Ciconia ciconia) of Eastern Germany: age-dependent breeding ability, and age- and density-dependent effects on dispersal behavior." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/3905/.
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Dispersal behavior plays an important role for the geographical distribution and population structure of any given species. Individual’s fitness, reproductive and competitive ability, and dispersal behavior can be determined by the age of the individual. Age-dependent as well as density-dependent dispersal patterns are common in many bird species. In this thesis, I first present age-dependent breeding ability and natal site fidelity in white storks (Ciconia ciconia); migratory birds breeding in large parts of Europe. I predicted that both the proportion of breeding birds and natal site fidelity increase with the age. After the seventies of the last century, following a steep population decline, a recovery of the white stork population has been observed in many regions in Europe. Increasing population density in the white stork population in Eastern Germany especially after 1983 allowed examining density- as well as age-dependent breeding dispersal patterns. Therefore second, I present whether: young birds show more often and longer breeding dispersal than old birds, and frequency of dispersal events increase with the population density increase, especially in the young storks. Third, I present age- and density-dependent dispersal direction preferences in the give population. I asked whether and how the major spring migration direction interacts with dispersal directions of white storks: in different age, and under different population densities.
The proportion of breeding individuals increased in the first 22 years of life and then decreased suggesting, the senescent decay in aging storks. Young storks were more faithful to their natal sites than old storks probably due to their innate migratory direction and distance. Young storks dispersed more frequently than old storks in general, but not for longer distance. Proportion of dispersing individuals increased significantly with increasing population densities indicating, density- dependent dispersal behavior in white storks. Moreover, the finding of a significant interaction effects between the age of dispersing birds and year (1980–2006) suggesting, older birds dispersed more from their previous nest sites over time due to increased competition. Both young and old storks dispersed along their spring migration direction; however, directional preferences were different in young storks and old storks. Young storks tended to settle down before reaching their previous nest sites (leading to the south-eastward dispersal) while old birds tended to keep migrating along the migration direction after reaching their previous nest sites (leading to the north-westward dispersal). Cues triggering dispersal events may be age-dependent. Changes in the dispersal direction over time were observed. Dispersal direction became obscured during the second half of the observation period (1993–2006). Increase in competition may affect dispersal behavior in storks. I discuss the potential role of: age for the observed age-dependent dispersal behavior, and competition for the density dependent dispersal behavior.
This Ph.D. thesis contributes significantly to the understanding of population structure and geographical distribution of white storks. Moreover, presented age- and density (competition)-dependent dispersal behavior helps understanding underpinning mechanisms of dispersal behavior in bird species.Das Verständnis der Mechanismen, die dem Ausbreitungsverhalten und der Wahl des Neststandorts zugrunde liegen, gibt wichtige Einsichten in Strukturen und Dynamiken von Tierpopulationen. Der Gesundheitszustand, die Produktivität und Konkurrenzfähigkeit sowie das Ausbreitungsverhalten eines Individuums können über das Alter ermittelt werden. Alters- und dichteabhängige Veränderungen in Verbreitungsmustern kommen bei vielen Vogelarten vor. In der vorliegenden Studie untersuchten wir zunächst den Effekt des Alters auf die Reproduktivität, auf die Wahl des Neststandorts sowie auf die Geburtsorttreue des Weißstorchs (Ciconia ciconia). Wir fragten, ob sowohl der Anteil der brütenden Individuen als auch die Geburtsorttreue mit dem Alter zunimmt. Weißstörche sind Zugvögel, die während der Migration zumeist segelnd die Thermik nutzen und in weiten Teilen Europas brüten. Nach einem starken Bestandsrückgang konnte in vielen Regionen Europas ab den 1970er Jahren wieder ein positiver Trend in der Populationsentwicklung beobachtet werden. Die zunehmende Populationsdichte, besonders nach 1983 in der ostziehenden Subpopulation in den fünf Bundesländern der ehemaligen DDR, erlaubte die Analyse von dichte- und altersabhängigen Präferenzen in der Richtung der Brutstandorte sowie in der Verbreitungsfrequenz und -distanz. Wir untersuchten zudem die Alters- und Dichteabhängigkeit der Ausbreitungsrichtung einer Teilpopulation. Wir fragten, ob und wie die Hauptzugrichtung im Frühjahr mit der Verbreitungsrichtung interagiert: Beeinflussen Alter und Populationsdichte die Ausbreitungsrichtung? Der Anteil der brütenden Individuen, die älter als 22 Jahre sind, nahm innerhalb der beobachteten Teilpopulation ab, vermutlich aufgrund einer altersbedingten Abnahme des Gesundheitszustands. Junge Vögel zeigten eine starke Geburtsorttreue, was auf eine genetische Komponente in den Zugmustern junger Störche hinweist. Generell trat bei jungen Störchen häufiger Ausbreitungsverhalten auf als bei älteren Störchen. Eine signifikante Zunahme der Ausbreitungsdistanz von Individuen über die Zeit lässt auf eine dichteabhängige Komponente im Ausbreitungsverhalten der Weißstörche schließen. Weiterhin wurde eine signifikante Interaktion zwischen dem Alter sich ausbreitender Individuen und dem betrachteten Jahr gefunden. Demzufolge breiteten sich alte Vögel über die Zeit über größere Distanzen aus, vermutlich um der ansteigenden Konkurrenz, bedingt durch den wachsenden Bestandsdruck, zu entgehen.
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O'Connor, Rory Sean. "The ecology and conservation of the Adonis Blue (Polyommatus bellargus) and the Chalkhill Blue (Polyommatus coridon) butterflies in the UK." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:a6d1b995-f416-4e07-9910-d49f5187618a.
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A combination of habitat loss, degradation and fragmentation are causing declines in butterfly species across Europe, with habitat specialists more vulnerable than generalists. The influence of climate change is serving to complicate matters, particularly at the edge of geographic ranges. Improving the quality of habitats is a key tool for the conservation of threatened species at both a local and landscape scale and this requires a thorough understanding of the ecology and habitat requirements of species. From this perspective this thesis examines and compares the ecology of two closely butterfly species, Polyommatus bellargus (the Adonis Blue) and Polyommatus coridon (the Chalkhill Blue) in southern England; calcareous grassland specialists, found in a highly fragmented ecosystem at the northern most edge of their geographic range. Chapter 2 explores whether there has been an expansion in the larval niche of P. bellargus due to a warming climate in recent decades, and finds no indication of change once concurrent local habitat change has been accounted for. Chapter 3 examines the role that differences in microhabitat requirements play in differentiating the larval niche of P. bellargus and P. coridon, showing P. coridon has broader microhabitat requirements. Chapter 4 experimentally examines the specificity of mutualistic interactions between the larvae of each butterfly species with the ants Myrmica sabuleti and Lasius niger. Chapter 5 uses microsatellites to explore the genetic structure of both P. bellargus and P. coridon, showing (as predicted) that P. coridon has a less fragmented population structure than P. bellargus, but both species have high levels of inbreeding.
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Trisos, Christopher Harry. "Tests of community assembly across spatial scales in Neotropical birds." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:7b836d0f-9ead-4409-8705-b8c7e7fb8935.
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Species diversity varies dramatically across the surface of the Earth. A key step in the accumulation of species diversity is the ability of species to coexist in biological communities. Thus, identifying the mechanisms underlying community assembly is a major challenge for ecologists seeking to explain patterns in species diversity and composition. Recently some consensus has been reached on the set of processes that influence community assembly: speciation, demographic stochasticity, niche-based fitness trade-offs among species and dispersal. However, it is unclear how the importance of a particular process changes with spatial scale, which interactions exist among processes at large spatial scales and the extent to which niche-based resource partitioning among species explains differences in diversity among communities. Neotropical birds offer an ideal opportunity to address these uncertainties because of their high diversity and the existence of detailed information on their evolutionary history and ecology. In this thesis, I first use trait and phylogenetic metrics of community structure to show that both habitat filtering and interspecific competition shape community composition at the scale of individual bird territories (~1-2 ha). Second, I use simulations of community assembly to show that trait-based metrics of community structure outperform phylogenetic metrics for detecting niche-based community assembly, and that both sets of metrics often have low power when multiple processes influence community composition. Third, taking a trait-based, species-level approach, I show that both habitat filtering and interspecific competition influence species occurrence at regional scales (~75000 km2), and interact with dispersal ability so that their effect on species occurrence is increased for species with greater dispersal ability. Finally, using a combination of trait- and isotope-based methods to quantify resource partitioning, I show that species' niche widths do not change and niche overlap is reduced at high compared to low species richness. Taken together, these results suggest that both habitat filtering and interspecific competition (i.e. niche-based processes) influence community assembly from local to regional scales. However, at least at regional scales, the degree to which these processes are important for determining the occurrence of any given species depends on that species's dispersal ability. They also suggest, based on niche-based interspecific competition influencing community composition, that differences in species richness among communities are in part explained by differences among sites in the breadth of available niche space, not by increased ecological specialisation or niche overlap.
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Dos, Santos Abade Leandro Alécio. "Human-carnivore conflict in Tanzania : modelling the spatial distribution of lions (Panthera leo), leopards (Panthera pardus) and spotted hyaenas (Crocuta crocuta), and their attacks upon livestock, in Tanzania’s Ruaha landscape." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:073a48ab-336a-45a1-ac9f-bc6996c1f58b.
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Tanzania’s Ruaha landscape is an international priority area for large carnivore conservation, harbouring roughly 10% of the world’s lions, and important populations of leopards and spotted hyaenas. However, these large carnivore populations are threatened by intense retaliatory killing due to human-carnivore conflict on village land around Ruaha National Park (RNP), mostly as a result of livestock predation by lions, leopards and spotted hyaenas. Moreover, a current lack of ecological data on the distribution of these carnivores hinders the development of effective strategies for conservation and targeted conflict mitigation in this landscape. This study aimed to identify the most significant ecogeographical variables (EGVs) influencing the distribution of lions, leopards and spotted hyaenas across the Ruaha landscape, and to map areas of conservation importance for these species. In addition, the study assessed the influence of EGVs on livestock predation risk by these carnivores in the village land around RNP, and generated a predictive map of predation risk. The relative importance of livestock husbandry practices and EGVs in terms of influencing predation risk within enclosures was also investigated. Proximity to rivers was the most important variable influencing the distribution of large carnivores in Ruaha, and contributed to predation risk of grazing livestock. The traditional livestock husbandry adopted in bomas appeared insufficient to alleviate the inherent risk of predation by large carnivores. The study produced the first detailed maps of lion, leopard and spotted hyaena distribution in the critically important Ruaha landscape, and identified likely livestock depredation hotspots. These results will target conflict mitigation approaches around Ruaha, by identifying particularly high-risk areas for livestock enclosures and grazing stock. Improving husbandry in these areas could help reduce livestock depredation and retaliatory carnivore killing, therefore reducing one of the most significant conservation threats in this critically important landscape.
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Bagniewska, Joanna Maria. "Diving behaviour and activity patterns of the invasive American mink, Neovison vison." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:8307169d-fa7e-4f99-a7a6-e7c16528bce4.
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Semi-aquatic mammals have evolved to forage in both aquatic and terrestrial environments, and they generally lack locomotor specialisation for either. Having relatively unspecialised adaptations, some semi-aquatic species are generalist foragers, and their activity and diving patterns provide insight into constraints on their foraging behaviour. The recent miniaturisation and improved accuracy of logging devices allow remote data collection from small (<1kg), shallow-diving species. The development of analytical methods has lagged behind technological advances (and techniques developed for fully aquatic animals do not account for the variability of behaviour typical of semi-aquatic animals and their switching between terrestrial and aquatic environments). I applied and developed novel analytical techniques to identify activities and diving patterns of a semi-aquatic mustelid, the American mink (Neovison vison), fitted with Time-Depth Recorders (TDRs). Using a hidden Markov model (HMM) algorithm allowed me to classify dives into three states to identify clustering, and describe sequential diving patterns by mink. TDRs were used to determine active/inactive periods on the basis of rapid TDR temperature changes, and this method was validated empirically. Having developed this methodology, I applied it to 18 datasets collected from 14 mink in lowland England. Terrestrial activity of mink was positively related to ambient temperature (across both sexes), however aquatic activity, especially diving, appeared to be more influenced by daylight than by temperature. Mink showed intersexual differences, with males being more nocturnal and more active on land, and females more diurnal, and more persistent in diving. There was considerable variability between sexes and individuals. This is the first study to use HMM to classify the dives of a semi-aquatic animal, and the first to use TDR temperature records to identify mammalian activity patterns. These methods will be generally applicable to animals that make rapid transitions between environments and have thus far been difficult to study.
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Kilshaw, Kerry A. "Introgression and the current status of the Scottish wildcat (Felis silvestris silvestris)." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:11c27f05-c051-4cbb-b498-538561005d87.
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Baseline data on a species' distribution and abundance are essential for developing practical conservation management plans. Such data are difficult to obtain for many low density cryptic carnivores. The Scottish wildcat, Felis silvestris silvestris, is no exception with <400 individuals thought to remain. Its conservation has been further complicated by extensive hybridisation and introgression with the domestic cat (F.s.catus). Hybridisation has also resulted in difficulties in discriminating between wildcats, wildcat x domestic hybrids (hybrids) and tabby coloured feral domestic cats. This has inhibited survey efforts, leading to a lack of general ecological information. Using the most recent identification tools available, extensive surveys using various methods including camera trapping were carried out across Northern Scotland in order to examine the current status of the Scottish wildcat. Current distribution indicates a more restricted range than recent studies. Wildcats are at risk of hybridisation from feral domestic cats and in particular, hybrids, throughout their current probable range. The distribution of hybrids overlaps with both feral domestic cats and wildcats, pointing to a significant threat from hybrids acting as a bridge between wildcats and feral cats. Mean density estimates of 3.5 (SD=0.7) wildcats/100 km2 were comparable with those from other studies in Scotland using different survey methods. Total population size estimates ranged between 115-314 individuals depending on local densities and home range size. Population viability analysis (PVA) indicated the current population is not viable unless management actions are undertaken in the near future (Mean time to extinction = 48.2 years (SD = 9.39), probability of extinction=1, SE = 0), and that reducing mortality rates and/or supplementing populations from captive bred cats are likely to be necessary to achieve viability. Based on these data, the Scottish wildcat may be more endangered than many other species classified as Endangered and the current status of the Scottish wildcat should be reviewed.
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Elliot, Nicholas Bryant. "The ecology of dispersal in lions (Panthera leo)." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:0cc8101b-1048-44ef-921e-1b44a2356c7e.
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As ecosystems become increasingly fragmented, there has been a proliferation of research into fields such as resource use, movement ecology and habitat connectivity. To understand how species may adapt to threats associated with habitat fragmentation it is necessary to study these processes in dispersing individuals. However, this is seldom done. Dispersal is one of the most important life-history traits involved in species persistence and evolution, but the consequences of dispersal are determined primarily by those that survive to reproduce. Although dispersal is most effectively studied as a three-stage process (departure, transience and settlement), empirical studies rarely do so and an investigation into the entire process has probably never been carried out on any one species. Here I investigate the survival, resource use, movement ecology and connectivity of African lions (Panthera leo) in all three dispersal phases in addition to adulthood. I make use of a longterm dataset incorporating radio-telemetry and observational data from lions in Hwange National Park, Zimbabwe. Dispersal is inherently risky and my results show that male lions that disperse while young suffer high mortality, young dispersal being brought about by high off-take of territorial males. Dispersing males may be aware of risks associated with territorial adults as they position themselves far from them and utilise habitats and resources differently. However, dispersers, compared to adult males and females, are far less averse of risky, anthropogenic landscapes, suggesting they are the demographic most prone to human-lion conflict. The ontogenetic movement behaviour of lions reflects a transition from directional movement during transience, suggestive of sequential search strategies, to random or periodic use of a fixed territory after settlement. In terms of habitat connectivity, I show that radically different conclusions emerge depending on which demographic is used to parameterise connectivity models. Understanding the shifting mechanisms that species adopt throughout ontogeny is critical to their conservation in an increasingly fragmented world.
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Monteiro, Pedro Tiago dos Santos. "Experimental studies in simple choice behaviour." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:ae36e6ba-c4ff-4b5f-9f49-5c921707baa2.
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This thesis addresses decision mechanisms in foraging situations, using laboratory experiments with European starlings (Sturnus vulgaris). Building on previous work from the Behavioural Ecology Research Group, I chose the Sequential Choice Model (SCM; reviewed in Kacelnik et al., 2011 − Appendix 1) as a starting point, and tested its premises and predictions generalising it to different experimental protocols. Classical decision models do not relate choice preferences to behaviour towards isolated options, and assume that choices involve time-consuming evaluations of all alternatives. However, previous work found that starlings’ responses to isolated options predict preference in choices, and that response times to single-option encounters are not reliably longer than response times in choices. Since, in the wild, options are normally encountered sequentially, dealing with isolated options can be considered of greater biological, and possibly psychological, significance than simultaneous decisions. Following this rationale, the SCM postulates that when multiple simultaneous stimuli are met they are processed in parallel, each competing against the memory of background opportunities, rather than comparing present options to each other. At the time of launching this research, these ideas had only been applied to protocols involving just two deterministic alternatives and offering no chance to explore the influence of learning history (i.e., how animals learn to choose; see Chapter 4). To increase their relevance and offer more rigorous tests, I generalised them to situations with multiple (see Chapters 2, 4 and 5), and in some cases probabilistic alternatives (see Chapter 3), controlling the learning regime. I combined these extensions with tests of economic rationality (see Chapter 6), a concept that is presently facing sustained debates. Integrating the result of all experimental chapters (see Chapter 7), my results support the notion that behaviour in single-option encounters is fundamental to understand choice behaviour. The important issue of whether choices involve a decision time cost or the opposite, a shortening of response times, remains unsolved, as neither could be evidenced reliably.
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Daly, Benjamin. "Avian malaria in the montane tropics." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:70284964-36b6-4135-98d4-4ec8d22c8b45.
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Understanding the unequal distribution of life on earth is a fundamental goal of ecology and evolutionary biology. Past efforts to explain large-scale patterns in diversity have tended to focus on two broad classes of explanation, one invoking the importance of abiotic factors (i.e. climate and vegetation) and the other biotic (i.e. competition); but neither has proven entirely adequate. Parasites are a major but poorly understood component of life that may offer some answers. Yet despite widespread theoretical support and some empirical evidence, the role of parasites in explaining patterns in the diversity, distribution, and abundance of species remains largely untested in natural communities. In this thesis I use a mega-diverse elevation gradient of birds as a model system to study the role of avian malaria in explaining these macroecological patterns. In the first data chapter I tested the extent to which patterns of infection across species is predictable. I found that the effects of host ecology and environment were weakly related to infection prevalence and were not consistent across different malaria lineages. Instead, I show that hosts coexisting with many close phylogenetic relatives consistently experience higher infection than evolutionarily distinct host species. In the second chapter I tested if parasite sharing may help explain these observed relationships and show that parasite sharing among host pairs declines with the time since divergence. Spatial contiguity between host pairs was also positively associated with parasite sharing. In the third chapter I tested how infection prevalence varies across species ranges in accordance with expected variation in host abundance. I show that birds are more likely to be infected at the centre of their elevation range, where host abundance is expected to be highest. Intriguingly, I also found that the incidence of host infection is unrelated to the position within the geographic range of the parasite. In the fourth data chapter, I tested whether parasites may regulate diversity by limiting geographic ranges of their hosts through ‘apparent competition’ in which a non-lethal parasite in a primary host, may be lethal in a secondary host. In support of this, I found that more observed bird ranges end at parasite infection zones than would be expected by chance. Taken together, my results suggest that parasites may play a major role in shaping patterns in the distribution and diversity of species, over both ecological and evolutionary scales. This is likely to arise and be maintained by host parasite interactions in which distantly related hosts are less likely to be infected by local parasites than close relatives, thus promoting the build up of diversity locally. On the basis of my analyses, I conclude that across montane elevation gradients in birds, and across diversity gradients more generally, parasites are likely to play a crucial role in the origin and maintenance of high biological diversity.
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Slade, Eleanor M. "The effects of tropical forest management on biodiversity and ecosystem functioning." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:d4689410-3c13-4e92-9f35-e4abe0d8e0ac.
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The Effects of Tropical Forest Management on Biodiversity and Ecosystem Functioning Eleanor M. Slade 1. Between 35 % and 50 % of all closed-canopy tropical forest has been lost, and the rate of deforestation continues to increase throughout the tropics. Despite a wealth of literature on the effects of tropical forest disturbance on the diversity and composition of a variety of taxa, there is still no clear consensus on the value of disturbed forests for biodiversity. 2. If forest management practises are to be sustainable in the long-term they should maintain both biodiversity and ecosystem functioning (the interactions and processes of the ecosystem), as well as a timber harvest. However, few studies have investigated the extent to which ecosystem functioning is reduced in logged forests. The effects of different logging intensities on a variety of taxa, and the ecosystem processes with which they are associated, were assessed in the Danum Valley Conservation Area in Sabah (Malaysian Borneo). 3. Even under high logging intensities, the forests of Sabah appear to have been managed in a way that maintains timber yields in the short-term. However, other aspects of forest structure had been affected, which could have important consequences ecologically, and for the long-term sustainability of timber harvests. 4. Combining field studies with manipulative experiments allows assessment of the impacts of species changes associated with habitat modification on measures of ecosystem functioning. Dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) functional group richness and composition were manipulated in a series of field experiments. Certain functional groups and species were found to have a greater impact on ecosystem functioning than others; nevertheless a full complement of species was needed to maintain full ecosystem functioning. 5. Dung beetles appeared to be relatively robust to changes in forest structure associated with selective logging, but species richness was reduced with high-intensity logging. There was a corresponding decrease in ecosystem functioning (dung and seed removal) with a decrease in species richness, and a decrease in the biomass of large nocturnal tunnellers, suggesting that although some species are dominant, rare species are also needed to preserve full ecosystem functioning. 6. A complex interaction between birds and ants resulted in reduced herbivory of seedlings of the important timber tree, Parashorea malaanonan, in some instances. However, this interaction was not affected by either selective or high intensity logging. Seedfall of P. malaanonan, was reduced in logged forest compared to primary forest. Despite insect seed predation being higher in primary forest, there was still successful recruitment during a non-mast year. Parasitism of insect-predated seeds was found to be inversely density dependent, and was higher in logged forest where seed predation was lower. 7. The results of this thesis suggest that the forests of Sabah appear to be being logged under a management system that is compatible with sustainable timber management, but not necessarily sustainable forest management. Low intensity selective logging seems to preserve much of the original forest structure, biodiversity and ecosystem functioning compared to logging at higher intensities. However, ecosystem processes were variable in their response to logging, suggesting that management decisions should be based on the consideration of multiple taxa and processes.
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Rodrigues, Antonio M. M. "Social evolution in class-structured populations." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e97720c2-f2c0-4fd9-9413-a1a7695069df.
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Inclusive fitness theory concerns the study of social traits. Often, individuals differ in their phenotype (e.g. size, weight, nutritional state) independently of their genetic make up, that is, individuals differ in their quality. Individuals can then be classified into different “classes” according to their quality, which enable us to understand social evolution in class-structured populations. This is important because individuals in natural populations often differ in quality, either because of intrinsic factors (e.g. size), or extrinsic factors (e.g. resource availability). My thesis concerns the evolution of social traits in class-structured populations. In chapter 1, I make a brief introduction to my thesis, providing the abstract of each chapter. In chapter 2, I outline a general theory of individual quality, where I show how individual quality impacts social evolution in two fundamental ways. In chapter 3, I show that resource heterogeneity greatly influences the evolution of conditional social behaviour. In chapter 4, I show that temporal group-size heterogeneity promotes the evolution of both conditional helping and harming. In chapter 5, I analyse the effect of individual quality on kin selection. I find that individual quality has an important impact in kin selection, which can lead to extreme forms of social behaviour. In chapter 6, I show that stable environments promote the evolution of negative density-dependent dispersal, while unstable environments promote the evolution of positive density-dependent dispersal. In chapter 7, I show that budding and low local quality promote the evolution of dispersal and cooperation.
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Bregman, Tom P. "The impacts of human land-use change on avian diversity and associated ecosystem functions." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b0364847-0949-4d9f-bf2a-2cca62a988a7.
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Understanding the impacts of land-use change on biodiversity and the ecosystem services that it provides is of great importance given unprecedented growth of the human population. Past studies attempting to explore these impacts have described the overall structure of communities (i.e. species richness and trait diversity) across gradients of local scale degradation and fragmentation, and have sought to identify whether the loss of species following land-use change is non-random. Yet, despite a wealth of research we still lack a generalised understanding of how land-use change impacts on traits responsible for determining species sensitivity and their role within ecosystems, particularly for vertebrates. Moreover, despite the importance of niche-based processes in the assembly of communities, we have not yet elucidated whether these are important in mediating the collapse of communities in human-dominated landscapes. To fill these existing research gaps, I collated comprehensive avian species inventories from fragmented and degraded forests and compared their structure with communities existing in continuous forests. In Chapter 2, I tested whether sensitivity of species to forest fragmentation varies between the temperate zone and the tropics and whether there are key differences in the size of fragments required to maintain ecosystem processes in these regions. I found that sensitivity to fragmentation varies according to functional group and body mass, with the prevalence of insectivores and large frugivores declining in relation to fragment size, particularly in tropical fragments smaller than 100 ha. In Chapter 3, I tested whether functional diversity and the mean position of trait diversity of insectivores and frugivores, changed across a gradient of intensifying land-use change. I found a decline in the functional diversity of forest species and a shift in the mean community traits for both forest and non-forest species. In Chapter 4, I tested whether the structure of tropical bird communities are influenced by species interactions in a fragmented landscape. I found increasing over-dispersion in functional and phylogenetic trait relatedness among species with decreasing fragment size, suggesting that competitive interactions are important in the disassembly of avian communities. In Chapter 5, I modelled the impact of forest cover change on ecosystem function across the Brazilian Amazon, focusing on seed dispersal by birds. Furthermore, I tested whether ecosystem function declined linearly with decreased forest cover after accounting for differences in the underlying pools of species. I found the lowest levels of functional diversity along the southern arc of deforestation and that the dispersal of large seeds showed some resilience to declining forest cover. Taken together, my results suggest that the loss of species from communities in degraded and fragmented landscapes is strongly non-random. Insectivores and large frugivores are most sensitive to land-use change, with species located in the densest parts of trait space being most threatened by a decline in forest patch size, suggesting that species interactions regulate the collapse of avian diversity in human-modified forests. I conclude that land-use change has important implications for the provisioning of ecosystem services, including seed dispersal and the control of insect herbivores. The impact of future land-use change is likely to be mediated by the composition of the original pool of species and the amount of redundancy in the ecosystem services that they provide. I discuss the relevance of my findings to land-use management strategies and policy interventions, and in particular conclude that these should, where possible, maintain pristine forest patches above 1000 ha, improve connectivity among habitat patches, and ensure greater protection for logged and burnt forests. Future studies should focus on clarifying the link between shifts in vertebrate community structure and the functioning of forest ecosystems.
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Barthold, Julia A. "A demographic perspective on trait heritability and sex differences in life history." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:94f04aac-182f-466b-a267-179d68db398f.
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Biologists have long used demographic approaches to answer questions in ecology and evolution. The utility of these approaches has meant a constant development and refinement of methods. A key milestone has been the development of phenotype structured population models that link ecology and evolution. Moreover, biostatistical research steadily improves methods to coax demographic information from scarce data. In this thesis, I build upon some of the recent advances in the field. My first three studies focus on the consequences of sex differences in life history for population dynamics. Firstly, I test whether males matter for the dynamics of African lion (Panthera leo) populations via a previously unquantified mechanism: the inheritance of phenotype from father to offspring. Secondly, I develop a method to estimate age-specific mortality rates for both sexes in species where one of the sexes disperses around the age of maturity. Thirdly, I apply this method to study variation in mortality between the sexes and between two populations of African lions. After these three chapters, which make contributions to the field of sex-structured population dynamics, I focus on the integration of phenotype structured modelling and quantitative genetics. I illustrate how heritability of a quantitative character that develops with age depends on (i) viability selection, (ii) fertility selection, (iii) the development of the phenotype with age, and (iv) phenotype inheritance from parents to offspring. Our results question the adequacy of quantitative genetics methods to obtain unbiased estimates of heritability for wild populations. This thesis advances our understanding of population development over ecological time scales. This knowledge has applications in conservation and population management, but also contributes to untangling evolutionary processes in wild animals.
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Aw, Justine M. "Decisions under uncertainty : common processes in birds, fish and humans." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:d6640108-012b-4e89-b4a5-512beb49c59f.
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Decision making is a framework we impose on a vast universe of possible behaviors to better understand the advantages and disadvantages of acting in different ways. Decisions under uncertainty are of particular interest because stochasticity is a feature of environments both today and throughout evolutionary history. As a result, we might expect decision makers (DMs) to have evolved mechanisms to handle variability. In this dissertation, I examine common decision processes in several model species: European starlings (Sturnus vulgaris), Banded tetras (Astyanax fasciatus) and humans (Homo sapiens). The broad range of approaches discussed include currencies DMs are expected to maximize (Risk Sensitivity Theory, Expected Utility), the currencies DMs do maximize (e.g. long versus short term rate maximizing models), the representation of outcomes in memory (Scalar Expectancy Theory) as well as explicit choice mechanisms (Sequential Choice Model). The first section of this thesis discusses responses to risk, offering humans and starlings choices between options which deliver certain or variable outcomes. Starlings demonstrate sensitivity to changes in the probability of variable outcomes and strong support for local rate maximization. Humans appear similarly sensitive to their own accuracy when task difficulty is varied. When the DM’s affective state was manipulated, neither humans nor starlings exhibit changes in risk preferences, but the effectiveness of these manipulations used could not be confirmed. Another topic of inquiry is the effect of the DM’s state at the time of valuation learning. State dependent valuation learning is demonstrated for the first time in a fish species, but Within Trial Contrast is not observed in starlings. Lastly, two experiments find strong support for the Sequential Choice Model, a promising new model of the mechanism of choice. Taken together, these experiments offer a glimpse into shared decision processes, but leave open questions about the mechanisms through which value is acquired.
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St, John Oliver Tudor Lockhart. "Genome engineering and gene drive in the mosquito aedes aegypti." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:1251080e-cf7b-4bdd-b01e-d01748ead2d2.
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Genetic control strategies are a novel method for reducing populations of pest insects such as the yellow fever mosquito Aedes aegypti, a major vector of several important arboviral diseases. This thesis describes efforts to develop new tools to engineer the Ae. aegypti genome and to better understand existing tools, and furthermore to use these to engineer a gene drive system in Ae. aegypti. The piggyBac transposon was found to be extremely stable in the germline of Ae. aegypti, and transposons engineered into the germline could not be remobilized with either an endogenous or exogenous source of piggyBac transposase. Conversely, somatic remobilization of piggyBac transposons was found to be readily detectable in the presence of a source of active transposase, the first report of such remobilization in Ae. aegypti. Toward new tools for genome engineering, the site-specific integrase from the phage φC31 was successfully used to promote exchange between a transgene cassette inserted into the genome of Ae. aegypti and a cassette in a plasmid vector, in the first demonstration of recombinase mediated cassette exchange technology in a pest insect species. The integrases from phages φRV1 and Bxb1 were not found to be active in the germline of the mosquito. Finally, development of a gene drive system in Ae. aegypti using an RNAi-mediated killer-rescue mechanism was attempted. Tissue-specific expression of tTAV-regulated-toxic effectors genes, using the promoter regions of the blood meal induced genes Carboxypeptidase A-1, 30Kb and Vitellogenin A, was possible, but sex-specificity was not achieved. A blood meal inducible lethal phenotype was not possible using the chosen promoters, with expression of the effectors either leading to death in early development or to a sublethal phenotype. RNAi against tTAV fused to the Mnp fragment of the dengue virus’ genome was tissue specific, but was found to be highly effective in the fat body suggesting that the Vitellogenin A was the best candidate for the engineering of killer-rescue systems in the mosquito.
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Sin, Yung Wa. "The major histocompatibility complex, mate choice and pathogen resistance in the European badger Meles meles." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:951310f6-63d8-4fbc-893a-dcd319e1a1d9.
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Studies of the evolution of the major histocompatibility complex (MHC) have been central to the understanding sexual selection and pathogen-mediated selection. The European badger Meles meles is well suited for exploring such questions because of its life history characteristics, reproductive biology and mating system. In this thesis, I examined both MHC class I and class II genes. Seven putatively functional sequences were found for class I genes and four for class II DRB genes. Evidence of past balancing selection of both genes was demonstrated by the dNdS ratio, by positive selection at the antigen-binding site (ABS) and by trans-species polymorphism of alleles within other mustelids and carnivores. MHC class I genes also showed evidence of concerted evolution, but domains showed different evolutionary histories. MHC genes may influence microbiota and odour of an individual and influence mating preferences. I examined the bacterial community of the subcaudal gland secretion and demonstrated a high number of bacterial species (56 operational taxonomic units), which cubs exhibited a higher diversity than adults. The microbiota may lead to an individual-specific odour as a cue signaling the MHC genotype of potential mating partners. I report the first evidence for a MHC- based mating preference in carnivores. Female badgers showed a MHC-assortative mate choice towards breeding with males that had functionally similar MHC genes, for MHC class II DRB genes. This applied to neighbouring-group matings. I also found considerable annual fluctuation in the occurrence of MHC-based mate choice. Based on genome-wide background in the same mating randomizations I found no evidence of inbreeding, which indicated that MHC similarity was apparently the actual target of mate choice. In line with MHC-assortative mate choice, MHC heterozygosity had no influence on the co-infection status. Individual MHC alleles did, however, associate with resistance and susceptibility to specific pathogens, suggesting that MHC diversity may be driven and maintained by pathogen-mediated selection through rare-allele advantages and/or fluctuating selection. My study of genetic characteristics, mate choice and pathogen pressures in a wild population revealed past and contemporary evolutionary process of the MHC genes. This increases knowledge of how the MHC may affect mating behaviour and sexual selection, ultimately influencing population processes.
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Godfrey, Elinor. "Social and environmental determinants of changing distribution and incidence of tick-borne encephalitis in Western Europe." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:fd0a7241-b85f-4d49-abe4-a5ec4057c96e.
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In Western Europe the incidence of tick-borne encephalitis (TBE) has increased over the last 30 years, coupled with changes in distribution. Modifications in the TBE enzootic cycle, through a combination of changes in temperature, vertebrate abundance and habitat suitability may have increased the risk of TBE in recent years. In Switzerland, analysis using satellite-derived climate data demonstrated that the environment of areas with TBE since the 1980s and areas that recently became endemic for TBE have become more similar between 2001 and 2009. This was coupled with an increase in April, May and June temperature, which could have affected the tick population and/or human exposure to ticks. Deer and boar abundance also changed in some cantons. In Germany, spatio-temporal modelling demonstrated the importance of temperature, vertebrate abundance and unemployment in the incidence and distribution of TBE between 2001 and 2009. Changes in TBE reporting, April, May and June temperature, vertebrate abundance and pesticide use may have contributed to increases in TBE in 1992 and 2001. Human exposure patterns, however, appear to be as important as the enzootic cycle in shaping the incidence of TBE, not only in determining the overall trend but also in interacting with the weekly, seasonal and yearly patterns of tick hazard to give the observed incidence. In Switzerland, in weeks with warm, sunny weather, human exposure to ticks is promoted and short-term increases in tick bites are seen. Human outdoor activity also shifts the seasonal pattern of tick bites, when compared with tick questing. There was no apparent increase in time spent in outdoor activities between the 1990s and 2000s in Italy, Germany and Austria, but survey data demonstrated that walking and hiking were already popular activities across Europe by the 1990s. The popularity of mushroom and berry foraging as a source of income in Latvia, Lithuania and Poland, coupled with the expense of vaccination, provide an inverse link between economic wellbeing and TBE risk. Correspondingly, in 2009, the economic recession was associated with an increase with TBE in these three countries.
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Tancoigne, Elise. "Évaluer la santé de la taxonomie zoologique : histoire, méthodes et enjeux contemporains." Phd thesis, Museum national d'histoire naturelle - MNHN PARIS, 2011. http://tel.archives-ouvertes.fr/tel-00707531.
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Ce travail est la première approche de la taxonomie zoologique basée sur les données de la plus grande base de données bibliographiques de zoologie, le Zoological Record, à l'aide d'outils scientométriques : méthodes cartographiques, comptages. Il remet en cause la conception selon laquelle la taxonomie serait menacée d'extinction, à l'instar de ses objets d'étude. Dans le contexte actuel de crise de la biodiversité, ce n'est pas une forme de déclin qui se révèle, mais plutôt une insuffisance des forces mises en jeu pour connaître l'ensemble de la biodiversité avant sa disparition. Ce travail sur les publications permet de donner une définition claire de cette discipline, et ainsi de proposer une nouvelle approche d'évaluation de sa santé. Puisque la taxonomie est définie comme la science qui travaille sur des collections naturalistes à des fins nomenclaturales, il est pertinent de proposer que sa santé soit évaluée en fonction du dynamisme de ses collections. Le déclin de la taxonomie n'étant plus considéré comme une donnée factuelle, il mériterait d'être abordé en tant que discours tenu par une communauté scientifique face à de profondes modifications de ses pratiques et face à la disparition de ses objets d'étude. Une approche relevant des sciences humaines traiterait sans doute avec profit cette thématique.
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du, Preez Byron Dennis. "The impact of intraguild competition with lion (Panthera leo) on leopard (Panthera pardus) behavioural ecology." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:6c17014e-2c58-40e5-866e-d1ce88fe0e89.
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Single-species research dominates the field of ecology; however there is a growing appreciation of the importance of a multi-species approach to holistic conservation. Carnivores exert a top-down control on other species, and are vital components of stable ecosystem functioning. Physiologically adapted for predation upon other animals, competition between carnivores can be particularly aggressive; frequently resulting in mortality, and even population suppression. Big cat research has historically focused on those species that are most easily observable; in particular the lion Panthera leo. The majority of the Felidae however are secretive and elusive, and receive relatively little scientific attention. In particular, there are few data available that measure the effect of direct intraguild interactions between carnivores. Using leopards Panthera pardus as a model species, this research aimed to investigate the impact of lions on the behavioural ecology of a socially subordinate carnivore. Leopards are the most abundant large carnivore in Africa, and have the largest global range of all felids; their ecological niche overlapping with that of both lions and tigers. The knowledge gained from examining their competitive interactions is therefore widely relevant, and may be applicable to other subordinate carnivore species that remain unstudied. Biotelemetry and camera-trap data were modelled using novel algorithms to show that lions impact on leopard population density, demographics and spatial ecology. Faecal analyses suggest that dietary niche segregation may facilitate sympatry. These results indicate the level of impact that large carnivores can exert over smaller species, and the potential for a focus on single-species conservation to undermine holistic conservation. The manifestation of intraguild competition has a significant influence on an animal’s ecology; leopards are generalist species that cope with persecution by adapting their behaviour and niche. Ecological specialists may not fare as well under competitive pressure, and proactive conservation initiatives may be required for endangered species.
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Psorakis, Ioannis. "Probabilistic inference in ecological networks : graph discovery, community detection and modelling dynamic sociality." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:84741d8b-31ea-4eee-ae44-a0b7b5491700.
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This thesis proposes a collection of analytical and computational methods for inferring an underlying social structure of a given population, observed only via timestamped occurrences of its members across a range of locations. It shows that such data streams have a modular and temporally-focused structure, neither fully ordered nor completely random, with individuals appearing in "gathering events". By exploiting such structure, the thesis proposes an appropriate mapping of those spatio-temporal data streams to a social network, based on the co-occurrences of agents across gathering events, while capturing the uncertainty over social ties via the use of probability distributions. Given the extracted graphs mentioned above, an approach is proposed for studying their community organisation. The method considers communities as explanatory variables for the observed interactions, producing overlapping partitions and node membership scores to groups. The aforementioned models are motivated by a large ongoing experiment at Wytham woods, Oxford, where a population of Parus major wild birds is tagged with RFID devices and a grid of feeding locations generates thousands of spatio-temporal records each year. The methods proposed are applied on such data set to demonstrate how they can be used to explore wild bird sociality, reveal its internal organisation across a variety of different scales and provide insights into important biological processes relating to mating pair formation.
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Belgard, Tildon Grant. "Comparative neurotranscriptomics in mammals and birds." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:932c796c-d219-4df3-85cc-7d9db19d7d6b.
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In this thesis I apply new sequencing technologies and analytical methods derived from genomics and computer science to the neuroanatomy of gene expression. The first project explores characteristics of gene expression across adult neocortical layers in a representative mammal – the mouse. Amongst the thousands of genes and transcripts differentially expressed across layers, I found common functional characteristics of genes that define certain layers, candidate cases of isoform switching, and over a thousand apparent long intergenic non-coding RNA transcripts. The second project compares patterns of gene expression in the structurally diverged adult derivatives of the pallium in mice and chickens. Overall, gene expression levels were moderately correlated between the two species. While expression patterns of ‘marker’ genes were only poorly conserved in these regions, there nevertheless was significant conservation of cross-species marker genes for homologous structures, cell types and functionally analogous regions. Many aspects of these data from both projects can now be easily browsed and searched from custom-built web interfaces. In addition to generating unprecedented genome-wide resources for the neuroscience community to explore the functional and structural dimensions of gene expression amongst different pallial regions in mammals and birds, this work also provides new insights into the widespread evolutionary shuffling of adult marker gene expression.
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Collet, Julie. "The operation of sexual selection in the red junglefowl." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:b6508a6a-ee77-4c2d-80fa-b43bca746901.
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Sexual selection acts on traits that increase the reproductive success of an individual in competition with other individuals of the same sex over reproductive opportunities, through intra-sexual competition and inter-sexual mate choice. Because males benefit more from remating than females, they are subject to more intense sexual selection. Modern genetic tools have shown that females often mate promiscuously, thus prolonging sexual selection after insemination through intra-sexual (sperm competition) and inter-sexual (cryptic female choice) episodes. Despite increasing interest in post-copulatory sexual selection, the implications of sperm competition, cryptic female choice and underpinning mechanisms remain little understood. This thesis adopts an integrated approach to quantify the relative importance of post-copulatory episodes in the operation of sexual selection, elucidate their proximate mechanisms in the red junglefowl Gallus gallus. By combining behavioural observations of replicate groups with paternity data, I show that female promiscuity decreased the total opportunity for sexual selection in a group, but accounts for an unexpectedly large proportion of the variance in male reproductive success. By comparing the operation of sexual selection on multiple male traits, I show that post-copulatory sexual selection reinforced pre-copulatory sexual selection for male social dominance and that female preferred to mate with compatible males. I used experiments to study the mechanisms of post-copulatory sexual selection by studying the effect of seminal fluid in sperm competition and cryptic female choice in relation to male status and relatedness. Following previous work indicating that seminal fluid products influence sperm quality in this species, I tested in vivo whether the seminal fluid of an ejaculate acts differentially towards sperm from the same ejaculate and rival sperm, and found no evidence for this idea. Finally, I show that cryptic female choice can drastically bias the outcome of sperm competition, and that female fowl might bias paternity toward unrelated males.
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Vandersommers, Daniel A. "Laboratories, Lyceums, Lords: The National Zoological Park and the Transformation of Humanism in Nineteenth-Century America." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1399640141.
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Davies, Gwilym. "Natural and bioinspired silk spinning." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:e7ec14e5-efff-4e19-b1a0-4c9f02ade678.
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This thesis describes an investigation into silk spinning, with the objective of producing high performance silk fibres in the laboratory using a novel spinning device based upon observations on natural spinning glands and processes. After an in-depth literature review the work is reported in two sections: natural and artificial spinning. The literature provides fragmented data on different aspects of natural silk production, and artificial spinning has not yet reproduced fibres with the properties of native silk fibres, despite unfounded claims of biomimetic spinning. The first half of the thesis looks at natural silk spinning. The work started with a general study of the morphology of spider and silkworm spinning ducts: First, how the silk fibre develops as the dope flows through the gland; and second the relationship between silk fibre properties and both gland morphology and spinning speed. More detailed studies using histochemical and spectroscopic investigations showed that the silk ducts of the spider Nephila edulis and the silkworm Bombyx mori both contain β-chitin, despite an evolutionarily distant common ancestor. Finally, observations showed that the duct of N. edulis consists of alternating nanoporous discs, and FEA modelling indicated that the duct is optimised for mechanical integrity and permeability. The second half of the thesis describes the development of a spinning device that uses natural silk dope mainly taken from B. mori as feedstock. It begins with a description of the gradual development of the engineering aspects of the spinning device, to meet challenges raised during the spinning investigation. The development of a centrifugal capillary rheometer, for practical quantitative insights into rheological processes is then presented. Finally the spinning investigation is reported: first, the screening of spinning in glass capillaries based upon natural gland dimensions and flow rates, which have been shown to induce fibrillation in silk dope in a rheometer, and also included initiation of instability through heat applied along the capillary; second, the final spinning evaluation, using lessons learned from all the screening trials throughout the project, but also including a key development of a hydrophobic coating on the capillary tip to inhibit droplet formation and massively increase the process stability and ease of fibre production. The main conclusions from this work are that good silk fibre cannot be spun by flow shear stress alone; and, that heat instability induces indiscriminate gelation of the silk, whose disordered molecular structure gives poor silk fibre properties. The body of work behind these conclusions provides fundamental background information and new insights that will contribute to the next stages of development of artificial silk spinning, from obtaining a better understanding of the biology of natural spinning glands to the engineering difficulties of implementing the bioinspired principles.
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Burns, Zackory T. "Quantifying the sociality of wild tool-using New Caledonian crows through an animal-borne technology." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:16db8026-53e4-4fb0-aa69-80d7cc34e183.
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New Caledonian crows (NC crows; Corvus moneduloides) are the most prolific avian tool-users and crafters, using up to three unique tool types derived from numerous plant materials. Since the discovery that wild populations of NC crows use and manufacture different tools in different locations with no measured environmental correlates to these distributions, the process by which NC crows acquire their tool-oriented behavior has been investigated. Two major findings were discovered in 2005: NC crows have a genetic predisposition to manipulate stick like objects, and they increase their rate of manipulation when exposed to social influences. Since then, much of the research into the sociality of wild NC crows has focused on direct social influences, especially the parent-juvenile relationship, yet no social network of wild NC crows has been described. In my thesis, I characterized a new proximity-logging device, Encounternet, and outline a four-step plan to assess error in animal borne devices; uncovered drivers, such as relatedness, space-use, and environmental factors, of wild NC crow sociality, and experimentally manipulated the social network, revealing immediate changes to the number of day-time and roosting partners, the breakdown of first-order relatedness driving sociality, and an increase in the amount of time NC crows associate; and revealed an indirect pathway via tools left behind by conspecifics allowing for the transmission of tool-properties between unrelated NC crows. Altogether, I furthered our understanding of wild NC crow sociality through the use of an animal-borne device, experimental manipulation in the wild measuring the response of the NC crow social network, and demonstrated the utility of animal-borne devices in mapping the network of a population of wild birds.
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Szulkin, Marta. "Inbreeding and its avoidance in a wild bird population." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:25e95465-f4ab-43ce-92e2-9d7fe88efeef.
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Inbreeding occurs when relatives mate and have offspring. Inbreeding depression is hypothesized to have influenced the evolution of mating systems and behavioural mechanisms of inbreeding avoidance in the animal kingdom. Inbreeding in the wild is difficult to measure, as in order to build a pedigree allowing us to identify matings between relatives, the identity of as many as possible members of a population needs to be known. For a long time, the main source of knowledge about inbreeding depression was based on laboratory and agricultural studies, which did not reflect the array of environmental pressures wild populations have to cope with. In consequence, the deleterious consequences of inbreeding have often been underestimated. This is problematic because accurate estimates of the effect size of inbreeding depression are needed to study the strength of selection on inbreeding avoidance mechanisms, and are also of importance to conservation genetics. The aim of this thesis was to use pedigree data to infer the occurrence and effects of inbreeding using over forty years of breeding events of the great tit Parus major from Wytham Woods, Oxfordshire. The effects of inbreeding on fitness were investigated across a life-history continuum, and across environments. I found that close inbreeding (f=0.25) resulted in pronounced inbreeding depression, which acted independently on hatching success, fledging success, and recruitment success, and reduced the number of fledged grand-offspring by 55%. My results therefore suggest that estimates of fitness costs of inbreeding must focus on the entire life cycle. I also show that the variation in the strength of inbreeding depression varies across environments, particularly so the more the environmental variable considered is linked to fitness. These results emphasise the need of using relevant environmental contrasts when investigating inbreeding by environment interactions. I further asked whether individuals involved in matings with relatives differed relative to individuals mating with unrelated partners. I did not find any evidence for clear predictors of inbreeding, and I show that inbreeding depression in our population is entirely independent of any tendency for low quality parental genotypes, or phenotypes, to inbreed. Neither did I find any evidence for active inbreeding avoidance: great tits did not mate less often with kin than expected based on several scenarios of random mating, nor did I find increased rates of extra-pair paternity among birds breeding with relatives. In fact, I observed quite the contrary, as birds mating with kin exhibited a higher than average rate of close inbreeding relative to all scenarios of random mating investigated, showed lower rates of extra-pair paternity and divorce than birds mated to unrelated partners. I hypothesise that cases of occasional inbreeding in this population may result from mis-imprinting or a related process whereby some birds develop particularly strong bonds that are at odds with all predictions of avoiding inbreeding. Finally, I asked to what extent natal dispersal, a behaviour that is often hypothesized to play an important role in avoiding inbreeding, indeed reduces the likelihood of inbreeding. I found that male and female individuals breeding with a relative dispersed over several-fold shorter distances than those outbreeding. This led to a 3.4 fold increase (2.3-5, 95% CI) in the likelihood of close inbreeding relative to the population average when individuals dispersed less than 200m. This thesis demonstrates that inbreeding has deleterious effects on a wild population of birds, occurring throughout an individual’s life, and is of varying strength across environments. My findings strongly support the theory that natal dispersal should be considered as a mechanism of prime importance for inbreeding avoidance.
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Oliveira, Crislaine de. "A zoologia nas escolas : percursos do ensino de zoologia em escolas da rede pública no município de Aracaju/SE." Pós-Graduação em Ensino de Ciências e Matemática, 2017. http://ri.ufs.br/jspui/handle/riufs/7158.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqThe Teaching of Sciences has been indicated as an important foundation in the school education for the formation of the citizen with the capacity to reflect and criticize the society, giving to this one the power and the desire to collaborate in its improvement. The present research had the purpose of analyzing the conceptions of science teachers of the state public school of education of the State of Sergipe on the teaching of Zoology. In order to do so, we sought to understand some specific points about the daily life of the teacher's classroom, such as: the teachers' conceptions regarding the content of Zoology of the textbooks used in the classroom; The resources that are most used by teachers when addressing the topics in Zoology; The occurrence or not of contextualization in the teaching of zoology and the mechanisms used to reach it; And what difficulties they encounter in the exercise of teaching. The research was structured in three stages, the first consisted in the survey of articles, dissertations and theses on teaching of Zoology and its contextualization; The second stage had the purpose of collecting data related to the beginning of teaching of teachers and their difficulties in the teaching of Zoology from the application of questionnaires, with closed and open questions, to 32 professors of Sciences and Biology; And the third part involved the application of semi-structured interviews with 10 teachers from the public school system, in order to deepen the questions about the teaching of Zoology, obtained in the questionnaires. The data indicate that the majority of teachers studied here are trained in the field of Biological Sciences Degree, and a few in Biomedicine and Pedagogy. Most teachers (88%) use the textbook, but a small portion (40%) considers that the book presents the contents of Zoology in an attractive and contextualized way. Most of the teachers (90%) affirm that they use the student's daily life, bringing their life experiences to the school context, and consider that this is contextualizing the teaching; however, their testimonies show that they only want to facilitate the understanding of the student, without raising questions and solving problems that lead to the formation of critical citizens. Most teachers claim to know how to make teaching motivational, but cannot find resources in school for this. Approximately half of the teachers (52%) said they had difficulties at the beginning of teaching and of these; the majority (38%) still did not overcome them. The most used methodology is the lecture class, but for these teachers the best methodology for the teaching of Zoology is the practical classes (39%). The greatest difficulties pointed out by teachers for the teaching of Zoology, verified both in the questionnaires and in the interviews, refer to those structures of the institution and the scarce time available to work the contents, being external to the teacher figure.
O Ensino de Ciências tem sido indicado como um fundamento importante na educação escolar para a formação do cidadão com a capacidade de refletir e criticar a sociedade, dando a este o poder e o desejo de colaborar em sua melhoria. A presente pesquisa teve como propósito analisar as concepções de professores de Ciências da rede pública estadual de ensino do Estado de Sergipe sobre o ensino de Zoologia. Para tal, buscou-se compreender alguns pontos específicos acerca do cotidiano da sala de aula do professor, como: as concepções dos professores a respeito do conteúdo de Zoologia dos livros didáticos utilizados em sala de aula; os recursos que são mais utilizados pelos professores ao abordar os temas na Zoologia; a ocorrência ou não de contextualização no ensino de zoologia e os mecanismos utilizados para atingi-lo; e, quais as dificuldades encontradas por eles no exercício da docência. A pesquisa foi estruturada em três etapas, a primeira consistiu no levantamento de artigos, dissertações e teses sobre ensino de Zoologia e sua contextualização; a segunda etapa teve o proposito de levantar dados relacionados ao início da docência dos professores e suas dificuldades no ensino de Zoologia a partir da aplicação de questionários, com questões fechadas e abertas, a 32 professores de Ciências e Biologia; e a terceira parte envolveu a aplicação de entrevistas semiestruturadas com 10 professores da rede pública de ensino, com objetivo de aprofundar as questões sobre o ensino de Zoologia, obtidas nos questionários. Os dados apontam que a maioria dos professores aqui pesquisados são formados na área das Ciências Biológicas Licenciatura, e alguns poucos em Biomedicina e Pedagogia. A maioria dos professores (88%) faz uso do livro didático, mas uma pequena parcela (40%) considera que o livro apresenta o conteúdo de Zoologia de forma atrativa e contextualizada. A maioria dos docentes (90%) afirma que se utiliza do cotidiano do aluno, trazendo suas experiências de vida para o contexto escolar, e considera que com isto está contextualizando o ensino, entretanto seus depoimentos mostram que pretendem apenas facilitar o entendimento do aluno, sem levantar questionamentos e resolução de problemas que levem a formação de cidadãos críticos. A maioria dos professores afirma saber como tornar o ensino motivador, mas não encontra recursos na escola para isso. Aproximadamente metade dos professores (52%) afirma ter enfrentado dificuldades no início da docência e destes, a maioria (38%) ainda não as superou. A metodologia mais utilizada é a aula expositiva, porém para esses professores a melhor metodologia para o ensino de Zoologia são as aulas práticas (39%). As maiores dificuldades apontadas pelos docentes para o ensino de Zoologia, verificada tanto nos questionários quanto nas entrevistas, referem-se aquelas estruturais da instituição e ao escasso tempo de que dispõem para trabalhar os conteúdos, sendo externas à figura do docente.
São Cristóvão, SE
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Annavi, Geetha. "Genetic, socio-ecological and fitness correlates of extra-group paternity in the European badger (Meles meles)." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:8d7304b2-84a2-4d5d-bbbc-63270d309e2e.
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The evolution of extra-group paternity (EGP) is a contentious issue in evolutionary biology. This thesis examines the factors and adaptive benefits driving EGP in a high-density, group-living population of European badgers (Meles meles). To improve power to assign parentage, I isolated and characterised 21 new polymorphic microsatellite markers. I genotyped 83% of 1410 badger trapped 1987‒2010 using 35 autosomal microsatellite markers. Maternity and paternity were assigned at 80% confidence ca. 82% of individuals. 48% of paternities were extra-group, where 85% were attributable to neighbouring-group males and EGP was detected in 47% of litters; thus badger social group do not correspond with a breeding unit. I tested whether indirect genetic benefits explain these high EGP rates. (1) ‘Good-gene-as-heterozygosity Hypothesis’: Paternal heterozygosity, but not maternal or an individual’s own heterozygosity, associated positively with first-year survival probability. Under benign environmental conditions, cubs fathered by more heterozygous males had a higher first year survival probability. Despite this correlation, the EGP rate per litter correlated with neither average nor maximum within-group heterozygosity of candidate fathers. (2) Fitness benefit Hypothesis: Extra-group offspring (EGO) had lower first-year survival probability and lived 1.3 years less than within-group offspring (WGO). Female WGO produced more litters and offspring over their lifetime than female EGO, whereas male EGO produced more offspring than male WGO. (3) Inbreeding avoidance hypothesis: The EGP rate within a litter increased with greater average pair-wise relatedness between mothers and within-group candidate fathers. No inbreeding depression on first-year survival probability was detected, but small sample sizes limited statistical power. Socio-ecologically, at the litter level, EGP correlated negatively with the number of within-group candidate fathers, and positively with neighbouring-group candidate fathers. In conclusion, EGP in badgers may reduce inbreeding and be maintained in the population through a sex-specific antagonistic selection and indirect genetic benefits may occur when the total fitness benefits of producing extra-group sons outweigh the costs of producing extra-group daughters. These indirect genetic benefits only partially explain the evolution of promiscuity in European badgers, highlighting that evolutionary factors underlying promiscuity remain unclear.
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Å, kerberg Sofia. "Knowledge and pleasure at Regent's Park : the gardens of the Zoological Society of London during the nineteenth century." Doctoral thesis, Umeå universitet, Historiska studier, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-59811.
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The subject of this dissertation is the Zoological Gardens of the Zoological Society of London (f. 1826) in the nineteenth century. Located in Regent s Park, it was the express purpose of the Gardens (f. 1828) to function as a testing-ground for acclimatisation and to demonstrate the scientific importance of various animal species. The aim is to analyse what the Gardens signified as a recreational, educational and scientific institution in nineteenth-century London by considering them from four different perspectives: as a pan of a newly-founded society, as a part of the leisure culture of mid-Victorian London, as a mediator of popular zoology and as a constituent of the Zoological Society's scientific ambitions. After an introduction which describes the devlopment of European zoos, Chapter two recapitulates the early years of the Society and the Gardens. The original aims of the Society—science and acclimatisation located in a museum and zoological garden—as stated in various prospectuses, are examined. The implications of acclimatisation, it being a problematic practice, are outlined and the connections between acclimatisation, the Society, the Gardens and the British Empire are also briefly considered. The founding of the Gardens is extensively described as well as how the animals were obtained and how exhibits were arranged. Chapter three is based primarily on the popular response to the Gardens in the 1850s when, after a period of decline, the institution once again became a common London visiting-place. The most important questions of this chapter concern the public and how it reacted to the Gardens of this period. The financial problems preceding the five years between 1850 and 1855 ^ described as well as how the Society managed to regain its popularity. This process was closely linked to the decision in 1847to let non-members of the Society enter the Gardens, and the implications of this resolution are discussed. As a background to the Gardens' popularity, two other London recreations are also described: the Colosseum Panorama and the Surrey Zoological Garden. The Surrey Zoological Garden especially is interesting, as it was a rival of the Society's Gardens, and the different attractions of these establishments are considered. Chapter four focuses on the official and non-official guidebooks to the Gardens and the implications of these as mediators of popular zoology. The historical and cultural connection between the guidebooks and travel handbooks is oudined and also how the genre as a whole is constructed. The progress and development of the Society's guidebooks during the nineteenth century is described and the differences between these guidebooks and the non-official ones are examined. Finally, with the aid of Victorian children's books, I argue that the guidebooks can literally be considered as travel handbooks since a visit to the Gardens may be regarded as a journey of knowledge. Chapter five is an in-depth study of the zoological science of the Gardens. The scientific work of the Society is briefly described, starting with the Committee of Science and Correspondence, and the Proceedings of the Zoological Society of London. The Proceedings reports that base their findings on animals in the Gardens are then described together with minor detours into the history of taxonomy and morphology.digitalisering@umu