Dissertations / Theses on the topic 'Ecology|Genetics'

I have studied the genetic variation of single species using morphological variation and enzyme electrophoresis. I have striven to understand the interaction between the breeding structure and the ecology of the species in relation to the community, in which it lives. The work was done in the county of Västerbotten, northern Sweden. In the Skeppsvik archipelago I have studied the population structure of Silene dioica: ecotypic variation in other populations. I have also studied the genetic diversity of Angelica archangelica, Bistorta vivipara, Viscaria alpina and the earthworm Eiseniella tetraedra along the free-flowing Vindel and Sävar Rivers and the regulated Urne River. The island populations of S. dioica are subdivided into several breeding units and levels of differentiation among subpopulations within islands were about twice as high as among islands. Restricted seed and pollen dispersal creates patches made up of related individuals that may diverge as a result of drift. Frequent seed and pollen dispersal occurs among islands and they will receive the same alleles. This may explain the pattern of differentiation observed. In contrast, the patches within islands may be founded by only a few individuals. * S. dioica exhibits morphological differentiation in vegetative and floral characters between serpentine, cold spring, rich forest and coastal habitats. There was no association between  genetic and geographical distance or between genetic distance and habitat. Serpentine and cold spring, which represented the most extreme habitats were also most differentiated. Populations of S. dioica are subject to herbivory; predation may exert a selective pressure on vegetative characters. A number of selective forces such as pollinators and fungal parasites act on reproductive characters. Assuming that water dispersal is important I tested several hypotheses to explain patterns of genetic diversity expected to be exhibited by riparian organisms along free-flowing and regulated rivers. I show that dispersal, distribution and breeding structure are important determinants of the evolution of the riparian flora. Patterns of genetic diversity may be exhibited at many spatial scales, e.g. among entire rivers, and between types of riverbanks within a river reach. Populations must be sampled at a spatial scale relevant to the hypothesis to be tested.

Diss. (sammanfattning) Umeå : Umeå universitet, 2002, härtill 5 uppsatser.

digitalisering@umu

Small and isolated plant populations have a higher probability of extinction – they are more susceptible to a range of environmental, demographic and genetic processes that may reduce population viability. In recent times, the number of populations and species that are susceptible to these processes has increased as a result of world-wide, human-induced habitat fragmentation. Habitat fragmentation typically reduces the formerly more continuous natural distribution of a species to a series of smaller and more isolated populations that occur in smaller and more isolated habitat patches. Such populations are often exposed to a range of additional processes that may threaten their viability, such as changes to disturbance regimes, environmental conditions and interactions with other species. However, our current understanding of the complex effects and interactions of these processes is poor. Species responses vary widely, studies are biased towards trees, herbs and self-incompatible species, and most studies investigate only one or two processes that may affect viability. Consequently, we are unable to make accurate predictions about the likely impacts of habitat fragmentation on population and species viability. I tested several hypotheses about the impact of habitat fragmentation, small population size, and population isolation on populations of two Grevillea species (Proteaceae) that occur in the Sydney region of New South Wales, Australia. These species provided an opportunity to investigate some of the ecological and genetic consequences of small population size and isolation, and to contrast them between a species for which the small size and isolation of its populations is the natural state (G. longifolia) and one for which it arose recently due to severe habitat fragmentation (G. caleyi). This comparative approach is important in identifying the processes involved in reducing population and species viability. The species share many aspects of their biology and ecology. Both are large, perennial shrubs that are self-compatible and naturally bird-pollinated. They are fire-sensitive and regenerate post-fire by mass germination from a long-lived, soil-stored seed bank. Both species consist of populations that vary dramatically in size and degree of isolation. I used microsatellite and AFLP markers to investigate aspects of the population genetics and mating system of these species, with the primary focus on G. caleyi. Both species showed a surprisingly large amount of genetic structuring among populations, although G. caleyi populations showed more structuring (FST = 0.46) than those of G. longifolia (FST = 0.33), despite being distributed over a much smaller area. In addition, for G. caleyi, most (63%) of the structuring was due to differences among recently-fragmented populations. By examining fine scale genetic structure within existing large populations, I determined that this was probably due to historic genetic structuring within formerly larger, more continuous populations. This has probably arisen due to both a lack of gene flow (no seed dispersal and limited pollen dispersal) and a large amount of inbreeding. Indeed, adult fixation indices were very high in G. caleyi (average f = 0.40, f > 0 in 16/18 populations). For both species, genetic diversity was not strongly correlated with population size. Genetic diversity was significantly lower in more isolated populations of G. caleyi, but this was probably due to a historic lack of gene flow to the more isolated parts of the species’ natural range, rather than to recent fragmentation. Levels of inbreeding (fixation indices) among adult plants did not vary with population size or isolation for either species. However, by genotyping fresh seeds from a range of small and large G. caleyi populations, I revealed that current outcrossing rates were much lower in small populations (t = 0.18 cf. 0.37). Observations of pollinator foraging indicated that this might be due to a very low visitation rate by birds and by a less diverse suite of species, resulting in a higher proportion of self-fertilisation. In contrast, even very small G. longifolia populations received many bird visits. In addition, G. caleyi plants in small populations were much smaller, had higher mortality, and produced fewer inflorescences and fruits, while this pattern was not apparent among G. longifolia populations. The contrast among the species in pollinator visits, plant vigour and reproduction may have been due to edge effects combined with the habitat degradation that was apparent at sites containing small G. caleyi populations. Small populations were typically found within very small and disturbed bush remnants, while small G. longifolia populations all occurred in relatively pristine habitat. Therefore, habitat quality rather than population size per se may be the most important factor that determines the mating system, plant vigour and fecundity in G. caleyi. The lack of obvious impacts of habitat fragmentation on the genetic haracteristics of adult G. caleyi plants may have been due to the soil-stored seed bank, which can contain seeds produced by at least two adult generations. Various authors have hypothesised that a persistent seed bank has the potential to reduce the rate of genetic change in a population. The seed banks of both G. caleyi and G. longifolia do appear to have this ability. I found that the seed bank of each species maintains the genetic characteristics of populations and stores genetic diversity and alleles that were not expressed in the extant adult plants. Nevertheless, the seed bank also showed greater spatial structuring than adults, which indicates that genetic changes may be occurring within these small populations despite the buffering power of the seed bank. Finally, I investigated some aspects of the ecology of G. caleyi and G. longifolia seed banks, with the aim of increasing our understanding of this important conservation resource. Soil sieving revealed that the seeds of both pecies occur at very low densities beneath adult plants (1 – 6 m-2), were vastly outnumbered by seed fragments, and were not found away from adult canopies. This supports previous evidence that indicated a lack of seed dispersal and very high rates of post-dispersal seed predation, which will restrict population size and extent. To some degree, the seed bank may buffer demographic changes that affected the previous adult generation – monitoring of post-fire seedling emergence revealed that population size typically increased, often dramatically, after a fire. Germination experiments showed that smoke elicited the greatest germination response from intact seeds of both species, and that dormancy polymorphism in the seed bank may allow both species to survive two fires in rapid succession and long inter-fire intervals. However, germination was low in field fire experiments, which may have been due to low fire intensity, and hence smoke production, resulting from a winter prescription burn. For both species, herefore, population viability may be compromised if the imposed fire regime includes fires that are too cool or too frequent. This study has demonstrated, for these species, that small populations that exist in recently fragmented habitat patches are far more likely to experience adverse ecological and genetic effects than those in continuous, relatively undisturbed, bushland. The process of demographic and genetic decline in small G. caleyi populations is likely to continue with the ongoing pressures of edge effects, habitat degradation and pollinator declines, and the increased isolation of some populations. The seed bank may buffer these declines to some extent, but this ability is limited by a lack of habitat for population expansion, which means that effective population sizes will remain very small or decrease further. The various differences detected between small and large G. caleyi populations emphasises the importance of large populations, and the ecological processes occurring within larger habitat patches, for the long-term conservation of the species.

This PhD Thesis includes five main parts on diverse topics. The first two parts deal with the trophic ecology of wolves in Italy consequently to a recent increase of wild ungulates abundance. Data on wolf diet across time highlighted how wild ungulates are important food resource for wolves in Italy. Increasing wolf population, increasing numbers of wild ungulates and decreasing livestock consume are mitigating wolf-man conflicts in Italy in the near future. In the third part, non-invasive genetic sampling techniques were used to obtain genotypes and genders of about 400 wolves. Thus, wolf packs were genetically reconstructed using diverse population genetic and parentage software. Combining the results on pack structure and genetic relatedness with sampling locations, home ranges of wolf packs and dispersal patterns were identified. These results, particularly important for the conservation management of wolves in Italy, illustrated detailed information that can be retrieved from genetic identification of individuals. In the fourth part, wolf locations were combined with environmental information obtained as GIS-layers. Modern species distribution models (niche models) were applied to infer potential wolf distribution and predation risk. From the resulting distribution maps, information pastures with the highest risk of depredation were derived. This is particularly relevant as it allows identifying those areas under danger of carnivore attack on livestock. Finally, in the fifth part, habitat suitability models were combined with landscape genetic analysis. On one side landscape genetic analyses on the Italian wolves provided new information on the dynamics and connectivity of the population and, on the other side, a profound analysis of the effects that habitat suitability methods had on the parameterization of landscape genetic analyses was carried out to contributed significantly to landscape genetic theory.

Field observations were collected to assess the social behaviour and foraging strategies of free-ranging killer whales from the eastern North Pacific (near Vancouver Island, Canada) and the western South Atlantic (near Peninsula Valdez, Argentina). The Vancouver Island study concentrated on the environmental correlates of group size and the behavioural dynamics of social groups. There were no correlations between foraging behaviour and small-scale habitat use, however both group size and the spatial distribution of groups were correlated with foraging behaviour. In Argentina the subject whales intentionally stranded to capture pup sea lions. It was possible to observe details of prey choice and foraging strategy. Three social groups were observed in the study area. Area use suggested that the different groups were employing different strategies. Whales within social groups shared prey, but one group would exclude another from the best hunting areas. Whales invested the greatest effort in the area of highest yield, and on the prey-type that required the least effort to catch. Energetic calculations suggested that the rate at which these whales captured sea lion prey was just sufficient to sustain them. Two genetic components, the hypervariable 'minisatellite' loci, and the mitochondrial genome were investigated for each study population. In addition, further samples from Iceland and other populations near the sites at Peninsula Valdez and Vancouver Island were analysed. Whales within social groups at Peninsula Valdez were more closely related than between social groups. In general, whales within local populations had very high levels of genetic similarity compared to between population comparisons. This implies inbreeding within and genetic isolation between populations. Two genetically isolated populations (both near Vancouver Island) were sympatric, and the degree of genetic isolation was equal to the level seen for comparisons between the Atlantic and Pacific. A hypothesis is presented on the role of resource exploitation in the structuring of social groups, and the consequences for the genetic structuring of populations.

Deer have been introduced outside their native ranges numerous times worldwide, causing significant economic and environmental impacts. The scale of problems caused by some introduced deer species is expected to increase, while others are relatively harmless and may be important for conservation as their numbers decline in native regions. This thesis examines the factors promoting invasion in non-native deer, and investigates the population genetics of two deer species introduced to Great Britain. Factors hypothesised to predict invasion success were tested using a comparative analysis of the outcomes of introductions of non-native deer populations. Two modelling approaches were taken to account for confounding effects in species-level and population-level analyses, and different factors were found to explain success at different stages of the invasion process. Populations of roe deer expanding from refugia and reintroductions were examined, and differences in genetic diversity between core and peripheral populations, alongside a decline in diversity with rate of expansion from the core were found. High levels of differentiation between and among core and peripheral populations suggest that genetic drift is the major factor causing these patterns. Using a genome scan of British and European roe deer, loci potentially under selection were identified. Association between some of these loci and environmental variables suggests that climatic extremes may have a role in exerting selective pressures on roe populations. The Chinese water deer is severely declining in range and number in its native habitat, but rapidly expanding after being introduced to Great Britain. Relatively high levels of diversity in native Chinese populations, and significant differentiation between the Chinese and British populations were found. The source population of the British deer is likely to be extinct, and the level of genetic structuring indicates that conserving populations across both ranges is important to maintaining their diversity.

Abstract Knowledge of the determinants of the viability of populations is essential in order to undertake effective conservation and management of endangered species. In this study, long-term demographic data was combined with genetic data to study the viability of an endangered orchid species, Epipactis atrorubens. The genetic analyses revealed low levels of genetic variation and the presence of population genetic differentiation independent of the spatial scale. Low levels of seed-mediated gene flow, possibly linked to low seedling recruitment, is the likely cause of the low levels of gene flow. Indications of slow post-glacial colonisation rates were found, which together with the low gene flow predict a limited capacity of the species to shift its range to more suitable habitats after environmental change. Low genetic variation as a proxy for low evolutionary potential also suggests that the species has limited capacity to adapt to new environmental conditions. Furthermore, poor seedling recruitment lowers population viability in small populations, as highlighted by the low population growth rates. In addition, we found a strong effect of stochasticity that limits the viability of populations. Both the genetic and demographic analyses indicated low viability of the studied species and that seedling recruitment could be the main determinant for the viability
Tiivistelmä Luonnonsuojelun perusta on populaatioiden elinkykyyn vaikuttavien tekijöiden tuntemus. Tässä väitöskirjatyössä tutkittiin uhanalaisen orkidean, tummaneidonvaipan (Epipactis atrorubens), elinkykyyn vaikuttavia tekijöitä yhdistämällä pitkäaikaisseurannoilla kerätyt demografiset aineistot geneettisin menetelmin kerättyihin aineistoihin. Lajin populaatioiden geneettisen muuntelun määrän havaittiin olevan pieni ja populaatioiden todettiin olevan geneettisesti erilaistuneita maantieteellisestä skaalasta riippumatta. Geneettisen erilaistumisen syy voi olla alhainen geenivirta, joka on seurausta vähäisestä siemendispersaalista ja huonosta taimettumisesta. Populaatioiden evolutiivista historiaa tutkittaessa havaittiin merkkejä hitaasta jääkauden jälkeisestä kolonisaatiosta, mikä yhdessä alhaisen geenivirran kanssa ennustaa, että lajilla on huono kyky siirtyä sille sopivammille alueille, jos ympäristö muuttuu. Huonoa evolutiivista potentiaalia kuvastava vähäinen geneettinen muuntelu ennustaa, että lajilla on huono kyky sopeutua uusiin ympäristöoloihin. Tämän lisäksi huono taimettuminen laskee elinkykyä etenkin pienissä populaatioissa, mikä näkyy muun muassa pienten populaatioiden matalina kasvukertoimina. Stokastinen vaihtelu vaikutti elinkykyä alentavasti, mikä pitäisikin huomioida nykyistä paremmin elinkykyanalyyseissä. Sekä geneettiset että demografiset analyysit osoittivat taimettumisen mahdollisesti olevan määräävä tekijä tummaneidonvaipan populaatioiden elinkyvylle

Extensive community-based sampling and single-species genetic analysis were used to study factors driving stream invertebrate community assembly on islands. Macroinvertebrates and physicochemistry were surveyed in forty-two streams on La Palma, La Gomera, Tenerife and Madeira (Macaronesia). Island faunal relationships and the role of the stream and catchment environment in determining community composition were investigated with multivariate analyses; assemblage nestedness and species richness, occupancy and abundance were also examined. The relationship between genetic differentiation and range size was tested using allozyme variation in selected species. Island species pools differed in community composition and species richness (total, and endemic), broadly as predicted by theory of island biogeography. Stream and island species richness were correlated, showing unsaturated, possibly dispersal-limited, communities, and stream faunas were nested, evidence that assemblages were not random (e.g. only generalist/dispersive taxa occur at species-poor sites). Endemics occurred in more streams than non-endemics, suggesting greater habitat availability for the former, but similar niche width, endemic and non-endemics having similar local abundance. Species richness, community composition and the abundances of individual species were correlated with stream physicochemistry, itself reflecting geology, rainfall, altitudinal zonation of vegetation and the intensity of stream exploitation. Allozyme variation was surveyed in Mesophylax aspersus (Trichoptera: Limnephilidae) and Wormaldia tagananana (Trichoptera: Philopotamidae), respectively having widespread and localised distributions. Population structure supported the hypothesis that range size is, at least partly, limited by poor dispersal ability in W tagananana. Genetic variation in Ancylus striatus (Gastropoda: Ancylidae) was typical of polyploidy and selffertilisation/ parthenogenesis. Breeding system has consequences for a species' colonisation ability, and may partially explain the wide distribution of A. striatus within the islands. Variation in community composition reflected patterns at a range of scales. Biogeography detennined the island species pooL whilst local physicochemistry determined richness and community composition within islands. Species characteristics that affect their colonisation and c:\tinction probabilities (e.g. habitat selection at the local- and mesoscaks, dispersal patterns and breeding system). influence hoth the local and regional species pools.

We can learn about the factors that promote and constrain speciation by comparing multiple instances of the evolution of reproductive isolation. It is particularly useful to compare systems with similar environmental transitions because natural selection is likely responsible for any evolutionary patterns that are consistently associated with ecological variation. In this thesis, I examine two cases of putatively similar recent or incipient ecological speciation in the sunflower genus Helianthus. In each case, the divergence observed between geographically adjacent populations is associated with adaptation to sand dunes. In my first study, I comprehensively test for reproductive isolation between dune and non-dune ecotypes of H. petiolaris. Despite their recent divergence, I find that multiple reproductive barriers separate them, including post-pollination assortative mating in the form of pollen competition. In addition, I find that a striking difference in seed size between the ecotypes is a consequence of divergent natural selection, and that it leads to strong and extrinsic reproductive isolation via selection against immigrants and hybrids. I then broaden my study to include the dune endemic, H. neglectus, which is sister to typical H. petiolaris. I look for chromosomal rearrangements between H. neglectus and H. petiolaris, and find almost as many large translocations between them as between more distantly related sunflowers. Finally, I discover that larger seeds are associated with dune environments in both systems and that the genetic basis of that phenotypic evolution is partiality repeated. Taken together, these results suggest that dune adaption within H. petiolaris and between H. petiolaris and H. neglectus has similar consequences. However, it remains to be seen whether assortative mating and chromosomal evolution are unique to the evolution of dune H. petiolaris and H. neglectus, respectively. Ultimately, understanding the similarities and differences between these systems will help answer the question - how predictable is speciation?
Science, Faculty of
Botany, Department of
Graduate

The long-term success of an introduced population depends on the ecological conditions in its new environment, but is also influenced by stochasticity. This is particularly clear in the first stage of an invasion when the population is still small and either goes extinct quickly or establishes a self-sustaining population. Once established, some populations grow and spread spatially, with potential impacts on native communities and ecosystems. The role of stochasticity during these later invasion stages remains unclear. Furthermore, little is known about the population genetic and evolutionary consequences of stochastic invasion trajectories. With this dissertation, I would like to contribute to a stochastic eco-genetic theory of the entire invasion process—from the first introduction up to potential impacts. The overarching questions in this dissertation are: a) How does a population’s movement through the invasion process depend on ecological factors influencing its average growth rate? b) How does it depend on factors influencing the stochastic variability in the population dynamics? c) How much genetic diversity do introduced populations harbor on average upon reaching a certain point in the invasion process? d) To what extent can the population-genetic consequences of invasion trajectories feed back onto the population dynamics? Together with my advisors and coauthors, I have conducted four studies, each addressing two or more of these questions for specific ecological scenarios. We employ several types of stochastic models: Markov chains, Markov processes, their diffusion approximations, and coalescent-like genealogy simulations. In Chapter 1 (Wittmann et al., 2013a, appeared in Theoretical Population Biology), we focus on a factor influencing the introduced population’s average growth rate: the intensity of competition with an ecologically similar native species. Our results indicate that the expected time until the introduced species drives the native competitor to extinction is smallest for intermediate competition intensity. This phenomenon results from the opposing effects of competition intensity at different points of the invasion process: On the one hand, intense competition renders the establishment of the introduced population more difficult; on the other hand, it facilitates the later exclusion of the native species. In Chapter 1, we also investigate to what extent the native species’ extinction is accelerated if a reduction in population size entails a reduction in genetic diversity and thus a reduced ability to adapt to a changing environment. We find this eco-genetic feedback to be particularly strong at small competition intensities. In Chapter 2 (Wittmann et al., 2013b, in press at Oikos), we compare introduction regimes with the same average number of individuals introduced per time unit, but with a different temporal distribution. Relative to regimes with many small introduction events, regimes with few large introduction events generate more variability in population-size trajectories. We show that this variability helps introduced populations to overcome difficult stages in the invasion process (those with a negative average growth rate), but is disadvantageous during easy stages (those with a positive average growth rate). In the light of our results, we can reinterpret three published data sets on invasion success under different introduction regimes. In Chapters 3 and 4 (Wittmann et al., 2013c,d), we examine levels of genetic diversity in populations that have successfully overcome a strong demographic Allee effect. In this ecological scenario, the average population growth rate is negative below a certain critical population size and positive above, such that the first stage in the invasion process is difficult and the second one easy. In Chapter 3, we assume Poisson-distributed offspring numbers. We show that compared to successful populations without an Allee effect, successful Allee-effect populations are expected to harbor either more or less genetic diversity, depending on the magnitude of typical founder population sizes relative to the critical population size. Part of the explanation is that, counter-intuitively, successful Allee-effect populations escape particularly fast from the range of small population sizes where genetic drift is strongest. In Chapter 3, we also identify conditions under which the critical population size can be estimated from genetic data. In Chapter 4, we consider a range of offspring-number models leading to either more or less variability in population dynamics than the Poisson model. For a fixed founder population size, we observe that the Allee effect has a negative influence on genetic diversity for small amounts of variability, but a positive influence for large amounts of variability. We show that the differences between our various offspring-number models are so substantial that they cannot be resolved by rescaling the parameters of the Poisson model. Taken together, these results offer some general conclusions with respect to the four main questions raised above. a) How fast an introduced population completes the invasion process is mainly determined by the presence and severity of difficult stages. Therefore, an ecological change promotes invasion success if it lessens such difficult stages. b) From the perspective of the introduced population, variability is advantageous during difficult but not during easy stages of the invasion process. c) Because the strength of genetic drift depends on population size, a key to understanding the population genetic consequences of invasion trajectories is to consider how much time the population of interest spends in different population-size ranges. d) Feedbacks between a reduction in population size and a loss of genetic diversity are strongest in ecological scenarios where the population of interest spends considerable time at small population sizes. Some of the most striking results in this dissertation cannot be understood from a deterministic point of view, but only when considering stochasticity. Thus, stochasticity does not just add “noise” to some average outcome, but can qualitatively change the behavior of biological systems.
Der langfristige Erfolg einer eingeführten Population hängt von den ökologischen Bedingungen in ihrer neuen Umgebung ab, aber auch vom Zufall. Besonders offensichtlich ist die wichtige Rolle des Zufalls für kleine Populationen im Anfangsstadium einer Invasion. In diesem Stadium entscheidet sich, ob die eingeführte Population nach kurzer Zeit ausstirbt oder sich dauerhaft etablieren kann. Manche etablierten Populationen wachsen dann weiter und breiten sich räumlich aus, zum Teil mit schwerwiegenden Folgen für einheimische Gemeinschaften und Ökosysteme. Bislang ist nicht klar, welche Rolle der Zufall in diesen späteren Invasionsstadien spielt und welche populationsgenetischen und evolutionären Auswirkungen vom Zufall geprägte Invasionsverläufe haben. Mit dieser Dissertation möchte ich beitragen zu einer stochastischen öko-genetischen Theorie des gesamten Invasionsprozesses – von der Einführung bis hin zu möglichen Auswirkungen. Meine übergreifenden Fragen sind: a) Welche Rolle für den Invasionsverlauf spielen ökologische Faktoren, die die durchschnittliche Wachstumsrate der eingeführten Population beeinflussen? b) Und welche Rolle spielen Faktoren, die die stochastische Variabilität der Populationsdynamik beeinflussen? c) Wie viel genetische Diversität weisen eingeführte Populationen im Durchschnitt auf, wenn sie einen bestimmten Punkt im Invasionsprozess erreichen? d) Inwiefern können die populationsgenetischen Auswirkungen von Invasionsverläufen wiederum die Populationsdynamik beeinflussen und so zu einer Rückkopplung führen? Zusammen mit meinen Betreuern und Koautoren habe ich vier Studien durchgeführt, die sich für bestimmte ökologische Szenarien jeweils mit mindestens zwei dieser Fragen befassen. Dazu kommen im Verlauf der Dissertation verschiedene Typen von stochastischen Modellen zum Einsatz: Markov-Ketten, Markov- und Diffusionsprozesse sowie Coalescent-artige Genealogie-Simulationen. In Kapitel 1 (Wittmann et al., 2013a, erschienen in Theoretical Population Biology) konzentrieren wir uns auf einen Faktor, der die durchschnittliche Wachstumsrate der Population beeinflusst: die Stärke der Konkurrenz mit einer ökologisch ähnlichen einheimischen Art. Unsere Ergebnisse deuten darauf hin, dass die erwartete Zeit bis zum Aussterben des einheimischen Konkurrenten für mittlere Konkurrenzstärken am kleinsten ist. Das können wir dadurch erklären, dass die Konkurrenzstärke gegensätzliche Auswirkungen in verschiedenen Stadien des Invasionsprozesses hat: Einerseits erschwert eine hohe Konkurrenzstärke die Etablierung der eingeführten Art, andererseits führt eine hohe Konkurrenzstärke aber auch dazu, dass die einheimische Art schnell verdrängt werden kann. Zusätzlich untersuchen wir in Kapitel 1, wie stark eine öko-genetische Rückkopplung das Aussterben der einheimischen Population beschleunigen würde. Dazu berücksichtigen wir, dass ein Rückgang der einheimischen Populationsgröße zu einem Verlust an genetischer Diversität führt, und das wiederum zu schlechterer Anpassung an veränderte Umweltbedingungen und darum weiterem Schrumpfen der Population. Unsere Ergebnisse legen nahe, dass diese öko-genetische Rückkopplung dann besonders stark ist, wenn die Konkurrenz zwischen einheimischer und eingeführter Art eher schwach ist. In Kapitel 2 (Wittmann et al., 2013b, im Druck bei Oikos) untersuchen wir für feste durchschnittliche Einführungsraten (Individuen pro Zeiteinheit), welche Rolle die zeitliche Verteilung der Individuen spielt. Besonders wichtig ist hierbei die Beziehung zwischen zeitlicher Verteilung und der Variabilität in der Größenentwicklung der Population. Wir zeigen, dass Fälle mit wenigen großen Einführungsereignissen zu mehr Variabilität führen als Fälle mit vielen kleinen Einführungsereignissen. Diese Variabilität hilft den eingeführten Populationen dabei, schwierige Stadien im Invasionsprozess (also solche mit einer negativen durchschnittlichen Wachstumsrate) zu bewältigen, ist aber anderseits in einfachen Stadien mit positiver durchschnittlicher Wachstumsrate von Nachteil. Im Lichte unserer Ergebnisse können wir aus der Literatur bekannte Daten zu Invasionsprozessen neu interpretieren. In den Kapiteln 3 und 4 (Wittmann et al., 2013c,d) untersuchen wir die genetische Diversität von Populationen, die einen starken demografischen Allee-Effekt erfolgreich überwunden haben. Laut Definition ist dabei die durchschnittliche Wachstumsrate bei Populationsgrößen unterhalb einer gewissen kritischen Größe negativ und in größeren Populationen positiv, so dass das erste Stadium des Invasionsprozesses schwierig ist und das zweite einfach. In Kapitel 3 zeigen wir unter der Annahme Poisson-verteilter Nachkommenzahlen, dass erfolgreiche Allee-Effekt-Populationen je nach Startgröße entweder eine höhere oder eine niedrigere durchschnittliche genetische Diversität aufweisen als erfolgreiche Populationen ohne Allee-Effekt. Das kommt zum Teil daher, dass erfolgreiche Allee-Effekt-Populationen besonders schnell das schwierige erste Stadium des Invasionsprozesses verlassen, wo genetische Drift am stärksten ist. Außerdem untersuchen wir in Kapitel 3, unter welchen Bedingungen sich die kritische Populationsgröße aus genetischen Daten schätzen lässt. In Kapitel 4 betrachten wir eine Reihe von Modellen für die Anzahl an Nachkommen von Individuen oder Paaren in der Population. Manche dieser Modelle führen zu mehr stochastischer Variabilität in der Populationsdynamik, andere zu weniger Variabilität als das in Kapitel 3 betrachtete Poisson-Modell. Für feste Startgröße beobachten wir, dass der Allee-Effekt bei kleiner Variabilität einen negativen Einfluss auf die genetische Diversität hat und bei großer Variabilität einen positiven Einfluss. Wir zeigen weiterhin, dass die Unterschiede zwischen unseren Nachkommenzahl-Modellen so substanziell sind, dass sie sich nicht durch eine Umskalierung der Parameter des Poisson-Modells erklären lassen. Zusammen genommen erlauben uns diese Ergebnisse einige allgemeine Schlussfolgerungen bezüglich der vier oben aufgeführten übergreifenden Fragen. a) Wie schnell eine eingeführte Population den Invasionsprozess durchläuft, hängt hauptsächlich davon ab, ob es schwierige Stadien gibt, und wie schwierig diese sind. Deshalb begünstigt eine ökologische Veränderung den Invasionserfolg dann, wenn sie schwierige Stadien im Invasionsprozess mindert. b) Aus der Perspektive der eingeführten Population ist Variabilität in schwierigen Stadien des Invasionsprozesses von Vorteil, aber in einfachen Stadien von Nachteil. c) Da die Stärke der genetischen Drift von der Populationsgröße abhängt, können wir die populationsgenetischen Auswirkungen von Invasionsverläufen verstehen, indem wir analysieren, wie viel Zeit die betrachtete Population in verschiedenen Populationsgrößenbereichen verbringt. d) Rückkopplungen zwischen einem Rückgang der Populationsgröße und einem Verlust genetischer Diversität sind am stärksten, wenn die Population viel Zeit im Bereich kleiner Populationsgrößen verbringt. Einige der wesentlichsten Ergebnisse dieser Dissertation können aus einer deterministischen Perspektive nicht verstanden werden, sondern sind ein direktes Produkt von Stochastizität. Dies macht deutlich, dass Stochastizität nicht einfach einem gewissen Durchschnitts- ergebnis etwas Rauschen hinzufügt, sondern das Verhalten biologischer Systeme qualitativ verändern kann.

There are two main parts in this thesis. The first one concerns valvometry, which is here the study of the distance between both parts of the shell of an oyster, over time. The health status of oysters can be characterized using valvometry in order to obtain insights about the quality of their environment. We consider that a renewal process with four states underlies the behaviour of the studied oysters. Such a hidden process can be retrieved from a valvometric signal by assuming that some probability density function linked with this signal, is bimodal. We then compare several estimators which take this assumption into account, including kernel density estimators.In another chapter, we compare several regression approaches, aiming at analysing transcriptomic data. To understand which explanatory variables have an effect on gene expressions, we apply a multiple testing procedure on these data, through the linear model FAMT. The SIR method may find nonlinear relations in such a context. It is however more commonly used when the response variable is univariate. A multivariate version of SIR was then developed. Procedures to measure gene expressions can be expensive. The sample size n of the corresponding datasets is then often small. That is why we also studied SIR when n is less than the number of explanatory variables p.

The past two decades have witnessed an unprecedented decline in Lepidopteran species, with more than a third of the UK’s butterflies now either considered threatened, or already lost from the country. The vulnerable marsh fritillary, Euphydryas aurinia, after a long term loss in the UK of 73% in abundance, has become an almost iconic species as the target of many well-funded conservation projects across the UK. Despite extensive ecological studies, populations of E. aurinia are shown in Chapter 2 to still be declining in south-west UK even after recommended management strategies have been implemented. This necessitates the need for prompt research beyond that of management requirements and butterfly habitat preferences. In Chapter 3, microsatellite markers (EST-SSRs) were developed for E. aurinia and using these markers in Chapter 4, it is shown that E. aurinia populations in southern UK and Catalonia, Spain, are severely genetically differentiated at all geographical scales, and genetically depauperate, causing huge concerns for the conservation of this enigmatic and ecologically important species. Dispersal is fundamental to metapopulation existence and survival. Phosphoglucose isomerase (PGI – an enzyme in the glycolysis pathway) is a well-endorsed candidate gene for dispersal, extensively studied in the Glanville fritillary (Melitaea cinxia) and Orange Sulphur (Colias eurytheme). In Chapter 5, an analysis across 27 sites in the UK discovered six non-synonymous SNPs (single nucleotide polymorphisms) within PGI. A single charge-changing SNP of interest showed no evidence of balancing selection, contrary to findings in M. cinxia, instead appearing to be neutral when analysed alongside microsatellite markers developed in Chapter 3. No link was found between genotype and flight, morphology or population trend. These findings challenge the emerging perspective that PGI could be used as an adaptive molecular marker for arthropods. Wolbachia are endosymbiotic bacteria capable of dramatically altering the reproductive system of their host. In Chapter 6, a PCR-based diagnostic in conjunction with MLST (multi-locus sequence typing) identified 100% prevalence of a single strain of Wolbachia across all sampled E. aurinia populations in the UK. Total prevalence suggests that Wolbachia probably has little phenotypic impact on its host, but the potential impacts of this endosymbiont on uninfected populations should be considered during any management plans for the conservation of E. aurinia. Current management plans will need to incorporate all areas of research, from basic ecological requirements to molecular adaptation and unseen manipulators of host biology, to be able to fully and effectively conserve declining fragmented species.

The reproductive ecology of three species of Decapod crabs, the shore crab (Carcinus maenas), the velvet crab (Necora puber) and the edible crab (Cancer pagurus), were studied in Swansea Bay and South Gower. Spawning occurs over winter and spring (shore crab), winter (edible crab), and summer (velvet crab). Berried females occur in spring and summer (shore crab), winter spring and summer (edible crab), summer and autumn (velvet crab). Eggs hatch in spring and summer (shore crab, edible crab), summer and winter (velvet crab). Copulation occurs in summer and autumn (shore crab), summer, autumn and winter (edible crab, velvet crab). Shore crabs from Swansea Queen’s Dock have a different reproductive cycle compared to the shore crabs from Tawe Barrage Impoundment and Mumbles Pier. More than one spawning periods or an extended spawning period was indicated for the shore crabs in the Docks. The genetic makeup of the shore crab populations present in Swansea Queen’s Dock and Mumbles Pier was compared using SSCP and cloning analysis of the 16S rRNA. Four different haplotypes were identified all of which were present in the Docks and one in the Pier, with low level of genetic divergence, and close relationship of the identified haplotypes with published shore crab haplotypes. AMOVA showed no significant difference between the study populations and published shore crab haplotypes. However, all identified haplotypes were different from published shore crab haplotypes, indicating a degree of reproductive isolation of the Swansea shore crab populations. Analysis of the permit return data for 1980-2002 of the edible and velvet crab fishery for the South Wales Sea Fisheries Committee District indicated that a combination of factors including overfishing, environmental conditions, and the “Sea Empress” oil spill in 1996 have contributed to a decline in landings that continues to date with limited signs of recovery.

The overall aim of this study was to improve understanding of the population genetics and basic ecological requirements of B. distinguendus in order to develop management advice and to direct conservation action. I used microsatellite genetic analyses to address questions about large-scale population genetics as well as finer-scale aspects of ecology. I found that populations of B. distinguendus throughout its Scottish range showed no significant inbreeding and little, if any, diploid male production. I also found that there was considerable gene flow between sites at a local scale (3 – 55 km), with significant differentiation only arising between widely dispersed (> 100km) island groups. At a finer scale I found that B. distinguendus nests at low density and is able to forage long distances from the nest. I also used standardised transect counts of bumblebees and flowers, together with pollen load sampling, to investigate bumblebee ecology. I examined the habitat use of foraging B. distinguendus (and other bumblebee species) in both a pastoral and a mixed farming system. There were strong positive relationships between the density of bumblebees and the density of flowers. The densities of different species of bumblebee were related to the densities of flowers of different plant species. I also examined the phenology and foraging ecology of B. distinguendus in the Hebrides. I found that B. distinguendus is a “late” emerging and nesting bumblebee, with a “medium” length colony cycle. I quantified the phenology of B. distinguendus  at ten important plant species and found that no single plant species provided resources throughout this colony cycle. I also found that B. distinguendus collected pollen from a limited range of plant species. During June and July, most pollen came from members of the Fabaceae, especially red clover (Trifolium pratense). In august, members of the Asteraceae were the most important sources of pollen.

Doctor of Philosophy
Department of Biology
Brett K. Sandercock
Samantha Wisely
Anthropogenic activities and climate change have dramatically altered landscapes worldwide. The ability of species to cope and adapt to ongoing changes is likely a function of their behavior, movements, and sensitivity to fragmentation. Greater Prairie-Chickens (GPC) are a lek mating grouse native to the Great Plains Landscape Conservation Cooperative (GPLCC), for which inbreeding depression and anthropogenic avoidance are a concern. The goals of my dissertation were to: 1) identify genetic correlates of male performance which may influence population viability under current land use practices, 2) identify GPC habitat characteristics and delineate areas of critical GPC habitat necessary for GPC conservation, and 3) identify the relative importance of distance and habitat quality for maintaining genetic connectivity among spatially structured populations. First, I found male reproductive success and survival to be positively associated with genetic diversity. Using multistate modeling in Program Mark, male survival across the observed range of variation in number of alleles (15-22) increased more than fourfold from 0.17 to 0.77. Second, I found 35-40% of Kansas, and 1.5 % (11,000 Km squared) of the GPLCC, were considered high-quality lek habitats. Top performing logistic models predicting lek presence (wi=0.95) included strong effects of grassland cover and avoidance of anthropogenic disturbance. When this model was applied to putative future landscapes based on climate change and current land use trends over a 70-year period, I found a 27-40% reduction in habitat area and a 137 Km southeast shift in habitat distribution. Under equilibrium conditions we expect isolation by distance (IBD) to explain the distribution of genetic diversity. However, if the landscape restricts dispersal, then we might observe isolation by resistance (IBR). I used model selection procedures to choose among competing IBR or IBD models to explain the distribution of genetic diversity among GPC populations across Kansas and the GPLCC. IBD was never supported (R-square<0.02, P>0.09). The best models for Kansas (R2=0.69, P<0.02) and for the GPLCC (R-square=0.46, P<0.02) indicated that human-mediated landscape changes have influenced landscape permeability for dispersal. The integration of behavioral, landscape, and genetic data provided new insights on prairie-chicken ecology, and is a powerful approach for developing conservation strategies for sensitive species.

The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which control it are surprisingly diverse. In this thesis, I examine sex determination in the plant species Mercurialis annua L. (Euphorbiaceae). I assess the mechanism of sex determination operating in dioecious and androdioecious populations of M. annua and also investigate the conservation and evolution of sex-determining mechanisms across the annual mercury clade, the lineages of which display exceptional variation in sexual system. First, using crosses, I establish that sex in dioecious M. annua is controlled by a single-locus genetic mechanism, consistent with recent work that identified a single male-linked DNA marker in the species. My search for new sex-linked genes revealed none, however, suggesting that M. annua possesses at most a small non-recombining region around sex-determining loci. Why many dioecious plants lack heteromorphic sex chromosomes is still poorly understood and I consider explanations for this. I extend my investigation by comparing genetic diversity between loci that differ in their linkage to the sex-determining locus. I find a single male-linked marker to possess significantly lower diversity than autosomal loci, but no difference in the diversity of partially sex-linked and non-sex-linked genes. I also assess the conservation of a sex-linked marker among annual mercury lineages and conduct crosses between lineages to examine the conservation of sex determination. My findings indicate a conserved mechanism of single-locus genetic sex determination and I consider the role polyploidisation and hybridisation have played in sexual system evolution and the modification of sex-determining mechanisms in the clade. Finally, I assess the presence of environmental sex determination in androdioecious M. annua, concluding that although male frequency is not influenced by growing density, a degree of sexual lability exists in the lineage.

Acanthodactylus boskianus is a common lizard species frequently occurring in different habitats throughout Egypt. Both males and females have well developed epidermal femoral glands. This species is territorial and males acquire dominance hierarchies in captivity. The current work included three different techniques to study the importance of femoral gland secretions in communication and signal evolution of A. boskianus. These are behaviour, chemical and DNA analyses techniques. Behavioural bioassays in different experiments showed that the femoral gland secretions are used in communication between the lizards. Communication includes possible roles in mate choice, agonistic behaviour between potential competitor males, and chemical trailing of scent pheromones. These behavioural results reflect the chemical results which showed the chemical variability between male ages, sexes, and allopatric populations. Chemical analysis of the secretions resulted in the identification of natural compounds not previously reported in reptiles, glycerolmonoethers and monoglycerides. The secretions seem to be used as scent pheromones, which are involved in signal evolution processes resulting in divergence of the chemical fingerprints of the gland secretion between allopatric populations.

Behavioral differences among closely related species can result from adaptation via natural selection, and this is especially true of innately expressed behavior that shows evidence of complex design or function. A major goal of biologists is to understand how and why complex, adaptive behavior evolves. To this end, I investigated the evolution, ecology and genetics of innate burrowing differences in deer mice (genus Peromyscus). First, I show that several species of deer mice recapitulate their natural burrowing habits under laboratory conditions. When I compare these behaviors in a phylogenetic context, I find that burrowing is species-specific and the complex burrows of the oldfield mouse (P. polionotus) likely arose from simple behavior similar to that expressed by two closely related species. Second, I examine the influences of soil composition and genetics on the burrowing behavior of oldfield mice. Although burrow length variation is relatively constant in nature, burrow depth is negatively associated with the silt content of soils. To determine the genetic architecture of complex burrowing, I crossed the oldfield mouse and its sister species, the deer mouse (P. maniculatus), which builds a relatively simple burrow. My results suggest that complexity results from the integration of several component behaviors: the lengthening of entrance tunnels and the construction of an escape tunnel. Additionally, complex burrowing segregates as a dominant trait and I identify four quantitative trait loci that influence burrow variation--three affect tunnel length and a single locus influences escape tunnel construction. Last, I test whether Peromyscus burrow socially. Specifically, I measure burrows constructed by both pairs of mice and individuals across three Peromyscus species with different social systems. Only in the monogamous species (P. polionotus), which is also the only species that builds complex burrows, do pairs of mice coordinate their behavior to build longer burrows. This effect of pairing increases burrow length in same-sex pairs of unrelated individuals, but it is most pronounced in male-female pairs, suggesting that oldfield mice invest most heavily in burrows constructed for the purpose of reproduction.

Regional habitat use by a species, dictated by the spatial and temporal availability of resources, influences its distribution patterns and ultimately population genetic structure. Seasonal migrations between geographically separated breeding and feeding areas, as occur in many baleen whales, can complicate these relationships. Here I try to integrate the population structure of minke whales over the whole North Atlantic with regional habitat use and behavioural adaptations to a particular summer feeding ground, the Hebrides off West Scotland. Whereas no genetic differentiation could be found between separate feeding areas as far apart as Canada, the UK and Svalbard, using microsatellites and mtDNA, the presence of two cryptic breeding populations was detected, which form mixed assemblages on feeding grounds across the North Atlantic. This implies fidelity to at least two breeding grounds irrespective of proximity to feeding areas, i.e. extensive seasonal migrations (over half the North Atlantic or more), which may require a re-assessment of current management stocks. These findings were consistent with the mobility and flexibility in habitat use and behaviour observed within the Hebrides. Results from Generalized Additive Models indicated that minke whale distribution was dependent largely on temporally variable parameters (temperature in spring, chlorophyll concentration in autumn), besides depth and, to a lesser extent, topography. However, fine-scale foraging behaviour was dictated primarily by the strength and direction of tidal currents. Distribution patterns according to environmental parameters changed through the season, but were largely consistent between the entire Hebrides (cell resolution of 4min) and a smaller core study area (2min), and over a time period of 15 years. Significantly higher sighting rates in areas of likely sandeel presence in spring, but not during the rest of the season, combined with prey samples from the core study area consisting almost entirely of sprat in August/September, indicate a switch in diet between early and late season and are consistent with the changes in habitat use. Site fidelity within the core study area was high only during periods of high feeding activity, but low at other times and between years, so that individual specializations to fine-scale feeding areas, as observed off Washington State, seem unlikely. Significant interannual changes in minke sighting rates between 2003-07, both within the core study area and over the entire Hebrides, were paralleled by changes in phytoplankton concentration, local sprat landings by the fishing fleet, and seabird breeding success and numbers counted at sea, particularly common guillemots. Auks were also the seabird guild that minke whales were most likely to associate with during foraging, taking advantage of tight bait-balls concentrated by them. The significant relationships with primary productivity make bottom-up control the most likely scenario for dictating concentrations of whale and seabird prey species in West Scotland. The ability to switch between different prey according to their availability through the season, and a distribution influenced by temporally variable parameters (temperature and chlorophyll concentration), combined with adjustments in foraging activity dependent on variable conditions at fine spatial scales (tides), enable minke whales to optimise exploitation of patchy prey concentrations.

In this study I aimed to investigate the genetic and ecological factors that may Influence the distribution and conservation of the Black Bog Ant, Formica picea, within the UK, where it is classed as an endangered species. All main UK F. picea sites known at the start of this study (Cors Goch Llanllwch, Carmarthenshire Rhossili Down, West Glamorgan Hartland Moor, Dorset the New Forest, Hampshire) were investigated. The first study of its kind of a UK ant species, this investigation involved measuring micro-geographic ecological parameters and using both microsatellite and mitochondrial DNA markers for genetic analyses. High percentage cover of Bell Heather (Erica tetralix) and Deer Grass ( Trichophorum cespitosum) in the immediate vicinity of the nest and a low density of Heather (Calluna vulgaris) in the local area occupied by F. picea appear to contribute to favourable habitat. Water table level may be the most influential determinant of F. picea nest distribution, however, as an unoccupied area appearing favourable in terms of E. tetralix and T. cespitosum cover revealed significantly lower relative humidity and vegetation height in 2003. Colonies of all studied populations were highly polygynous, containing multiple reproducing queens per colony, and two populations revealed significant levels of inbreeding. Isolation by distance was detected in two populations, suggesting nest reproduction by budding and poor dispersal. All populations were genetically differentiated from one another, with the exception of the physically closest pair. Within Cors Goch Llanllwch a degree of social polymorphism was identified, with two sectors showing differing levels of polygyny and polydomy (multiple nests per colony). Aggression between non-nestmates was absent in this population, suggesting a largely unicolonial organisation. Despite relatively large population sizes conferred by polygyny, UK populations of F. picea are at risk due to ecological specificity, inbreeding and limited dispersal. Within this study I make suggestions for conservation management including detailed ecological analyses and colony relocation.

Bumblebees are ecologically and economically important as pollinators, but some species are suffering severe declines and range contractions. In this thesis, three cryptic bumblebee species are studied to elucidate differences in their distribution, ecology and population genetics. As a result of their high morphological similarity, very little is known about the lucorum complex species: B. lucorum, B, cryptarum and B. magnus. In this study, their distributions across Great Britain were assessed using molecular methods, revealing that B. lucorum was the most abundant and most generalist of the three species, whereas B. magnus was the rarest and most specialised, occurring almost exclusively on heathland. Additionally, both B. magnus and B. cryptarum were more likely to be present at sites with cooler summer temperatures. Cryptic species represent interesting models to investigate the levels of niche differentiation required to avoid competitive exclusion. Characterising the niches of these species at a single site across the flight season revealed differences along three niche dimensions: temporal activity, weather sensitivity and forage-resource use. These species exhibited asymmetric niche overlap; a combination of ecological divergence and spatio-temporal heterogeneity may contribute to maintaining them in sympatry. Population genetic studies can be highly informative for understanding species ecology and for conservation management. The differences in habitat specialisation exhibited by these bumblebee species provide the opportunity to test conflicting hypotheses about links between dispersal and ecological specialisation: are habitat specialists selected to have low or high dispersal ability? Based on microsatellite analysis, the generalist B. lucorum had high levels of genetic diversity and little population structure across large spatial scales. The habitat specialist B. magnus had the lowest genetic diversity but similar levels of population differentiation to the moderate generalist, B. cryptarum. However, unlike B. cryptarum, B. magnus population differentiation was not affected by geographic distance, suggesting that this specialist species may maintain effective dispersal across large scales despite being restricted to a fragmented habitat. Bergmann’s rule is a well-known ecogeographic rule describing geographical patterns of body size variation, whereby larger endothermic species are found more commonly at higher latitudes. Ectotherms, including insects, have been suggested to follow converse Bergmann’s gradients, but the facultatively endothermic nature of bumblebees makes it unclear which pattern they should adhere to. This thesis reports caste-specific differences in body size between the three lucorum complex species in agreement with Bergmann’s rule: queens and males of B. cryptarum and B. magnus, which were found more commonly at higher latitudes and at sites with cooler temperatures, were larger than those of B. lucorum. Population genetic studies of invertebrates generally require the destruction of large numbers of individuals, which is often undesirable. Testing a variety of faecal collection and DNA extraction methods demonstrated that it is possible to obtain DNA of sufficient quality for genotyping from bumblebee faeces, without harming the individuals. This method would be valuable for studies of rare or declining bee species, for queens in reintroduction projects, and may be applicable to other arthropods. Overall this thesis contributes substantially to our knowledge of the ecology and population genetics of three important pollinator species. It provides data to inform species conservation, as well as understanding of ecosystem functioning and population dynamics. Furthermore, it successfully uses these cryptic species as a model to test several fundamental ecological theories.

Bibliography: p. 237-249.
This study investigates the population genetics and behavioural ecology of the Greywing Francolin, Francolinus africanus, and identifies factors which influence the distribution and abundance of this important gamebird. It also develops scientifically sound management strategies which should allow the maintenance of populations at levels which will produce sustained and economically viable hunting yields as a co-product of agriculture. Examination of genetic variability based on allozymes disclosed estimates of average within-population heterozygosity higher than that for most birds, and for all other galliformes for which data are available. Thus, Greywing apparently have a high degree of population stability and large effective population sizes. Indirect estimates of migration and several significant allelefrequency differences between nearby coveys suggest that there is a greater degree of genetic subdivision among Greywing populations than among populations of other birds. However, although the data suggest that populations are genetically differentiated on a large geographical scale, they also indicate that there is considerable dispersal, which produces outbred subpopulations on a fine geographical scale. Greywing therefore have a wealth of genetic variability that may 'buffer' populations against environmental changes, responsible hunting and/or short-term demographic bottlenecks. They also appear to undergo sufficient migration so that recruitment from adjacent populations will ensure population stability in hunted areas.

Eastern and Carolina hemlock in the eastern United States are experiencing high mortality due to the invasive non-native hemlock woolly adelgid (HWA). The most promising means of control of HWA is the importation of natural enemies from the native range of HWA for classical biological control. Prior to release, natural enemies must be tested for suitability as a control agent, including the ability to locate the target prey. Coleopteran predators, including Scymnus coniferarum and Laricobius osakensis are under consideration as a means of biological control of HWA. Laricobius nigrinus was released in hemlock forests in 2003. It was recently discovered to hybridize with the native Laricobius rubidus. Behavioral responses of these predators to HWA and host tree foliage were observed using a 4-chambered olfactometer, and genetic analysis was used to differentiate responses of L. nigrinus, L. rubidus, and hybrids. In the olfactometer, insects are allowed to amble about the arena and respond to volatile cues from each treatment. Host foliage with and without HWA was tested, as were various comparisons of eastern versus western foliage, host versus non-host foliage, and foliage containing HWA and a congeneric feeding beetle. Olfactometer bioassays demonstrated that foliage from hosts where prey is commonly found is preferable to foliage where prey is seldom found, and that the presence of HWA-induced volatile cues is the strongest driver of behavior, and trumps the presence of a competitor. There is evidence in the study that supports the reliability-detectability phenomenon common in parasitoid biological control agents. Hybrid individuals were found to behave similarly to released L. nigrinus, although in some cases intermediate behavioral traits were evident, with respect to the parental species. This study and others support the continued need for strict testing of potential biological control agents prior to release, as well as a strong impetus for the inclusion and implementation of genetic analysis as a standard component of agent evaluation.

Maintaining intraspecific variation is important for populations’ long-term success and is increasingly being recognized as an important conservation goal. Populations in anthropogenically fragmented habitats may lose variation rapidly via genetic drift, particularly in small fragments with a high ratio of edge to interior habitat. We studied the population and ecological genetic effects of habitat fragmentation on both a foundation plant, Spartina patens, and a dependent herbivore, Tumidagena minuta, using a naturally fragmented, salt marsh model system. We employed microsatellite marker analyses to estimate various measures of genetic variation, including allelic richness and heterozygosity, and to estimate the strength of genetic drift using estimates of effective population size (Ne). To achieve this, we developed a new program to estimate Ne and developed new markers for S. patens from genome sequence data. We found lower S. patens genetic variation and lower T. minuta Ne near the S. alterniflora edges, indicating that T. minuta experience stronger genetic drift near edges. These findings reinforce the importance of habitat patch shape in influencing populations.

Across most of the range of Leisler's bat (Nyctalus leislen) it is rare and considered vulnerable but, in Ireland, its European stronghold, it is considered of international conservation importance. Using molecular data from mtDNA and nuclear markers, this thesis examines the taxonomy, phylogeography, population genetic structure and mating system of N.leisleri throughout its range while focusing on Irish populations. Novel sequencing data for mtDNA control regions were generated for 64 specimens from Ireland and 36 from elsewhere and analysed with available sequence information N. azoream, N. I. verrucosus, and N. leisleri. 52 mtDNA haplotypes were divided into two divergent mtDNA lineages (2% sequence divergence, four fixed mutations). One lineage (Azorean) comprised haplotypes restricted to the Azores, Ireland and Britain; the second lineage (European) comprised haplotypes found throughout continental Europe. Unique European haplotypes in Ireland and Britain do not occur in the rest of continental Europe. Thus, Ireland constitutes a zone of secondary contact between two mtDNA lineages that evolved independently in separate refugia during the last glacial maxima. Some degree of genetic exchange has taken place between these lineages, most Iikely1 0,000 to 20,000 years ago. Current gene flow among the Azores, Ireland, Britain, and the European mainland, is virtually non-existent. . While species status remains debatable, N. azoreum and N. leisleri populations from the Azores, British Islands, and European mainland, comprise three distinct evolutionary lineages with very limited interaction Le. speciation is in progress. Thus, they represent three evolutionarily significant units from a conservation and management perspective. Eleven species specific microsatellite loci, developed for N. leisleri, were used independently or in combination with mtDNA data, to examine population structure and mating. Genetic population differences were found between mainland European and Irish nursery colonies confirming that gene flow does not occur, and N. leisleri do not undertake the largescale migrations between summer and winter roosts characteristic of populations in continental Europe. Within local regions, however, there is considerable gene flow among nursery colonies such that these are likely to constitute a population network or metapopulation. Nuclear and mitochondrial DNA discordance suggests that gene flow is male biased, with females showing natal philopatry. Within nursery roosts, overall relatedness was low for adult females and juveniles (both sexes). This low level of relatedness is likely due to low fecundity and a highly promiscuous mating system with no male dominance. ThUS, inbreeding is rare. This study has important implications for the conservation and management of N. leisleri. It highlights the importance of Irish populations of N. leisleri and its unique evolutionary history. Protection of Irish populations of this species should be a high priority. Supplied by The British Library - 'The world's knowledge'

The general aim of this research was the analysis of the mating system and the genetic structure of the southern elephant seal (Mirounga leonina). The specific objectives were to: 1) estimate the distribution of paternity and the relationship between behavioural and genetic indices of male reproductive success; 2) quantify the level of kinship among seals and investigate the presence of any genetic pattern that might be a consequence of the social structure of the population; 3) assess the genetic variation among and within the stocks of the Southern Ocean and analyse the pattern of individual dispersal. The research was conducted at Sea Lion Island (SLI, Falklands), from 1996 to 1998. All breeding males of the colony, and females and pups belonging to seven harems (n = 455) were tissue sampled. The samples were analysed at nine microsatellite loci and likelihood based paternity analyses were conducted. Samples (n = 46) from Elephant Island (EI, South Shetlands) were also characterised at the same microsatellite loci, and the mtDNA control region (299bp) was sequenced in 57 seals from SLI and 30 from EI. The success of the paternity inference was very high, as a father was found for 95.3% of the pups. Out of 183 assigned paternities, 151 (82.5%) were secure at the 95% confidence level and 32 (17.5%) at the 80% level. The distribution of paternities indicated an extremely polygynous system, with the majority of males achieving zero paternities and the harem holders siring up to 96% of the offspring in each harem (mean 78). Paternity was highly correlated with behavioural indices of mating success (R(^2) 0.80-0.99), and predicted individual paternities 60%-100% of the time in each harem. Elevated relatedness values (R) within colony suggested some level of philopatry, though the low F(_ST), indicated female dispersal between SLI and EI. Females from SLI showed a general higher level of relatedness among each other than did males. However, the harem structuring did not lead to any detectable genetic substructure within the population. Genetic differentiation was found both within and among putative colonies of the Southern Ocean. The differentiation at mitochondrial markers was higher than at nuclear markers, pointing to a difference in the pattern of breeding dispersal between sexes. Despite the extensive mitochondrial variation (ɸ(_ST)= 0.5), genetic evidence of male mediated gene flow was also found between SLI and Macquarie Island (MQ), as an adult male on SLI showed the same haplotype as a seal belonging to the very well-defined MQ lineage. Given the pattern of genetic diversity and patterns of fidelity and dispersal in elephant seals, the most parsimonious interpretation is that the male travelled from MQ to SLI. He successfully reproduced in 1996 on SLI, fathering at least 18 offspring. His exceptional migration demonstrates that even populations separated by wide genetic and geographic distances can remain linked, and it is an example of the potential homogenising effect that dispersal and mating system can have on the genetic patterns of a population.

Bumblebees are essential pollinators but, worldwide, many species are declining. The Tree Bumblebee, Bombus hypnorum, is a notable exception in that, having been first recorded in the UK (in southern England) in 2001, it has since rapidly spread to become common in much of England, Wales and Scotland. In this thesis I therefore investigated the ecology and genetics of B. hypnorum in the UK to better understand the factors underlying ecological success in bumblebees as a whole. In Chapter 2, I used biological recorder data to model and estimate B. hypnorum's dispersal kernel. I found evidence for leptokurtic dispersal, with most queens dispersing a relatively short distance (mean, 4.3 km) but a few dispersing much further (e.g. 1% dispersing up to 23.9 km). In Chapter 3, I used a panel of neutral genetic markers (microsatellites) to investigate the demographic history of a representative UK B. hypnorum population. I found no evidence for a recent population bottleneck, suggesting that, rather than being the product of a single, chance event, B. hypnorum's colonisation of the UK may be better explained by continuous migration from continental Europe. In Chapter 4, I used the same marker set to reconstruct the colony membership of workers sampled from a landscape in two successive years and to estimate the mating frequency of queens. This revealed notably short colony-specific worker foraging distances (mean, 103.6 m), high, variable nesting densities and a mean frequency of 1.7 matings per queen. In Chapter 5, I investigated the foraging ecology of B. hypnorum in the field and found that an absolute advantage in efficient flower handling and not low flower constancy ('generalism') may be contributing to its ecological success. Overall, these results greatly increase our understanding of the mechanisms by which bumblebees achieve ecological success and hence should help inform their conservation.

The ecological requirements of the Mediterranean breeding population of Lesser Crested Tern Thalasseus bengalensis emigrata were studied from 2009 to 2012 at its three breeding sites on the Libyan coast Libya: Gara, Elba islands and Jeliana islet. Four main research aspects were investigated: Breeding ecology, young diet structure and differences between sites, migration and recruitment, and population genetics. Threats and conservation measures were also discussed. This Mediterranean endangered population starts breeding at one site (Jeliana) three weeks earlier than in the other breeding sites, possible causes were discussed, including difference in migration routes and food diversity and availability among sites. Incubation period and nesting density were variable among sites; large colonies had more packed nests than in small colonies. A fourth breeding site was discovered in 2010 at Fteha Island. Nest counts at Jeliana colony tripled in 2012, following site restoration work that increased both the islet surface breeding area and height, to control nest inundation and competition on nesting space. Regurgitated food during young ringing was collected to study diet structure and diversity. Fish were the most common prey type with a small proportion of Cephalopods at Gara. Dominant fish families were Clupiedae, Exocoetidae, Hemiramphidae, Carangidae, Sparidae and Blennidae. Prey diversity was highest at Jeliana. There were more differences in prey structure among sites than within sites and seasons. Total length (TL) of fish was smaller at Elba compared to both Gara and Jeliana. Annual variability of prey mass were significant among sampling years, possible causes were discussed. Prey fish length increased with the progress of provisioning period, reflecting increased dietary demand by the growing young. Adults are potentially selecting actively for larger sizes. The relationship between the increase of Sea Surface Temperature and the primary productivity and fish spawning season coinciding with the Lesser Crested Tern breeding season have been discussed. 544 young terns were ringed during the study years, in addition to 808 that were previously ringed between 2006-2008 seasons. Ring sighting and recoveries constitute 2.07% of the total ringed terns; this allowed the gathering of more data on post-natal movements (staging and wintering ranges), breeding site philopatry and recruitment levels, in addition to a preliminary estimation the duration of migration journey. The population genetics of the study subspecies have been studied using two mitochondrial DNA molecular markers (ND2 and Cyt b). DNA samples were collected from Libya, the Red Sea and the Persian Gulf breeding populations. Irrespective of the relatively small sample size and the limited number of genetic markers used, there was significant genetic variability among the three populations. Several private haplotypes have been firstly identified for each population; few others were shared among all subspecies populations. Haplotype diversity was highest at the Persian Gulf subspecies T. b. torresii. The present three subspecies classification is found to be valid, which in turn making the Mediterranean breeding population a special conservation unit, given its relatively small population size and the limited breeding range. A model presents the breeding temporal and spatial aspects, related habitat requirements and present threats have been designed, based on data collected in this study. Habitat requirements and factors known to affect the population at wintering and staging sites were included in the model. The lack of legal protection, the potential oil pollution and site disturbance by visitors, poachers and habitat degradation were the top threats facing the Mediterranean subspecies. Mitigation measures and a proposed Action Plan was presented and discussed. The present research has answered several questions on the status, ecology, feeding, genetics and management of the Mediterranean breeding Lesser Crested Tern colonies in Libya. It is considered a significant step towards the conservation of this localised un-protected population.

Fragmentation of natural vegetation is currently one of the largest threats to biodiversity. Within the southwest Australia global biodiversity hotspot, the Swan Coastal Plain was historically cleared for agriculture and forestry and is now experiencing extensive land clearing for urbanisation. The wavy-leaved smokebush Conospermum undulatum is a rare species endemic to the Swan Coastal Plain, and its future persistence is threatened by urban expansion. Throughout this research, I investigated the pollination ecology of this species and found a specific association between C. undulatum and native bees for pollination. I also demonstrated that C. undulatum has evolved pollen with resistance to the usually negative effect of ant secretions on pollen grains, with ants providing effective pollination services to this threatened species. Native pollinators were drastically reduced in small populations, and urbanisation limited the movement of pollen across built-up areas surrounding remnant bushland. This lack of both pollinators and inter-population pollen flow is severely limiting the production of healthy seeds in smaller populations. I then performed molecular investigations combined with an ecological characterisation of the recently fragmented distribution range of C. undulatum to quantify the genetic structure and levels of genetic diversity across the entire distribution of the species. Despite the current intense fragmentation, I found levels of genetic diversity similar across populations and a weak spatial genetic structure. Since habitat fragmentation is recent and many adult plants are likely to be several decades old, they mainly reflect pre-fragmentation conditions. Therefore, the detailed characterization of fragmentation over time has shown how the low levels of genetic fixation can be attributed to pervasive gene flow through the pre-fragmented landscape, which mostly influenced the current adult cohort. Early signals of the negative effects of habitat fragmentation were found during my study of contemporary gene flow through the paternity assignment of seedlings sampled at the end of the 2017 flowering season. Although gametes of C. undulatum could flow unimpeded through large expanses of unfragmented bushland, inter-population pollen flow was non-existent between fragments surrounded by built-up areas. This study supports the need for an understanding of contemporary mating patterns to detect early signals of gene flow failure in fragmented remnants. Lastly, I found evidence for hybridisation occurring at the edge of the distribution of C. undulatum between this rare and threatened plant and two other related species. This adds to the threats posed by habitat fragmentation to the conservation of C. undulatum. My research highlighted the importance of native pollinators for plants that coevolved with them and adds to the limited research on the effect of habitat fragmentation on native plants that rely exclusively on native insects for pollination. Such pollinators appeared unable to maintain an adequate inter- population pollen flow in heavily fragmented landscapes. Therefore, the often negative effects of habitat fragmentation can be exacerbated in small and isolated populations of plants that rely on species-specific pollinators for sexual reproduction. Outcomes of my research will inform recovery plans to enhance the future persistence of C. undulatum over the long term.

Pine species (genus Pinus) have been introduced across the Southern Hemisphere for forestry and several species have invaded surrounding ecosystems. Pine introduction across biogeographic regions sets up an ideal natural experiment to test underlying theories and assumptions of invasion biology. We studied the factors determining patterns of Pinus contorta invasion across nine sites in both the native and introduced ranges to understand how the invasion drivers change across sites and invasion stages. We found that propagule pressure is the most important factor in explaining invasion density in young invasions, but that biotic factors play an important role at later invasion stages. Additionally, we found higher invasion densities in the introduced than native range which may be explained by faster growth and earlier and more prolific reproduction in the introduced range.

We examined the impacts of ^{P. contorta} invasions on plant biodiversity across sites and found that species richness and native plant cover decline with increasing ^{P. contorta} cover across sites in both the native and introduced range. There were more significant changes in species composition and individual species cover at grassland and shrubland sites in the introduced range than in the native range or a native forest site in the introduced range.

Finally, there is concern that invasive pines, which are fire adapted, will alter fire regimes in a way that promotes a new fire-prone state further increasing their success over native plants. We examined the potential for ^{P. contorta} to form a positive feedback with fire by quantifying fuel loads and fire effects across an invasive gradient. We also examined ^{P. contorta} and native plant recovery following fire across an invasion density gradient. We found that fuel loads and simulated soil heating increased with older ^{P. contorta} invasions. Following fire, ^{P. contorta} dominated communities only when the pre-fire density was high. Therefore, we expect that a positive feedback between ^{P. contorta} invasion and fire will form only above an invasion threshold. Our invasion-fire simulation model suggested that fire in older invasions will increase invasion rates, but that fires in young invasions will not affect the invasion rate.