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1

Ross, Caroline Ann. "Life-history strategies of primates." Thesis, University College London (University of London), 1989. http://discovery.ucl.ac.uk/1349897/.

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This thesis examines variation in the life-history parameters of primates using comparative techniques. Several theories of life-history evolution are introduced in the first chapter, together with a summary of the previous work on this topic. Scaling methods are used to separate variation in life-history parameters that is correlated with body weight from that which cannot be predicted from an animal's size. These methods are described in detail in Chapter 2. Chapter 3 describes the variation found in body size and basal metabolic rate and correlations with phylogeny, diet, habitat and other aspects of ecology. Patterns of variation in reproductive parameters, particularly reproductive rates (as measured by the intrinsic rate of natural increase, r_{max}) and reproductive effort (as measured by prenatal and postnatal infant growth rates), are described and compared with patterns reported in other studies. Possible reasons for the scaling relationships found are suggested and the influences of metabolic rate, phylogeny, diet, habitat and other aspects of ecology are investigated. This is carried out for all primates in Chapters 4-6 and in Chapter 7 there is a closer look at the cercopithecine monkeys. It is suggested that r_{max} is influenced by the predictability of the environment, with more unpredictable environments being associated with a higher r_{max} that more predictable environments. However, this is only found when body weight effects are removed from the r_{max} data. Growth rates do not appear to be correlated with environmental predictability but are mainly correlated with body size and relative metabolic rate. There is some indication that the degree of parental care may also be correlated with relative growth rates. It is concluded that no single theory of life-history evolution can amount for the variation found in primate life-histories, but that some aspects of several theories may be useful in describing the patterns found.
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2

Watson, A. P. "Life history strategies in fungal breeding Drosophila." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382839.

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3

Manyanga, Phelex. "Evolution of life history strategies in Lophoziaceae." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/6130.

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This study used data from literature and data from the field to analyse the patterns of variation in life history characters among members of the liverwort family Lophoziaceae. A combination of Principal Component and Cluster analyses was used to analyse data from literature in testing for recurrent suites of life history variation among species of the family. Data from literature were also used to examine the relationship between mode of reproduction and reproductive system (sexuality) and between diaspore (spore or gemma) frequency and sexuality. Data from the field were used to establish diaspore (spore and gemma) sizes and their production per capsule or shoot and to test for relationships between diaspore size and production per shoot/capsule and also between diaspore sizes and proportion of germination.
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4

Niva, Mikael. "Life History Strategies in Linnaea borealis." Doctoral thesis, Uppsala : University Library : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3604.

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5

Caradine, Emma L. "The life-history strategies of riparian spiders (Araneae)." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29774.

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This thesis addresses the life-history strategies of cursorial riparian spiders using field- and laboratory-based research. Species distributions were compared to important habitat variables with particular reference to disturbance. The nature of a "habitat templet" for riparian spiders was also examined. No 'typical' riparian spider fauna was identified. Most dominant species were opportunistic aeronauts, associated with disturbed habitats. Disturbance accounted for little variation in distributions. This is attributed to all sites being disturbed, with the actual frequency of flooding having little influence. Light penetration, the proportion of sand in the substrate, amount of exposed substrate and leaf-litter depth all significantly influenced the distribution of spiders. The influence of disturbance on the life-history traits of two congeneric and co-habiting lycosids (Paradosa argicola and P. amentata) was examined using manipulated levels of flooding. This showed that both species have evolved different strategies to cope with the consequences of flooding. P. amentata, a widespread generalist, had more plastic development periods and instar sizes across different treatments. Traits of P. agricola, a habitat specialist, were not plastic and this species has evolved a greater tolerance to flooding. Examination of the reproductive strategies of P. agricola and P. amentata revealed that both species can adjust their reproductive output. Both species produced smaller clutches later in the season. Offspring of these clutches had larger instars and shorter development periods, which is assumed to increase juvenile survival in conditions of greater environmental stress. No trade-off existed between the numbers and sizes of eggs within clutches. Maternal body size, however, was positively associated with clutch size and weight. Maternal size had no influence on egg sizes.
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6

Weisser, W. W. "Foraging and life history strategies in multi-trophic communities." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240464.

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7

Nakano, Mariko. "Life history strategies of an amphidiploid species, Drosera tokaiensis." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147869.

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8

Ichie, Tomoaki. "Resource allocation strategies along life history of dipterocarp trees." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150870.

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9

Shipway, John Reuben. "Aspects of the life history strategies of the Teredinidae." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/aspects-of-the-life-history-strategies-of-the-teredinidae(46eb09dc-f79c-4fa8-88aa-3c3ac172b121).html.

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The Teredinidae are a major economic pest of wooden coastal structures, causing billions of Dollars worth of damage per annum. To fully understand the threat posed by teredinids it is necessary to examine their biology at a number of different levels. These include: the anatomical adaptations which facilitate their wood-boring and wood- feeding life-style; the mechanism of cellulose digestion, which is aided by cellulolytic symbionts retained in bacteriocytes on the teredinid gill; the early life history strategies, particularly larval development; improving the means of teredinid identification for this taxonomically challenging group; and monitoring the spread of teredinids and the impacts global warming may have on their distribution. This thesis set out to address a number of these questions. The teredinid Lyrodus pedicellatus is able to complete a life-cycle feeding exclusively on wood and is one of the most destructive of the marine borers. In this study, X-ray micro-computed tomography (MicroCT) was used to produce a three-dimensional computer-rendered model of L. pedicellatus, to examine the anatomical adaptations for wood-digestion. This was complemented by a transcriptomic analysis of the major digestive organs, which set out to determine whether L. pedicellatus is capable of independently producing cellulolytic enzymes. Investigation of the early life history strategy aimed to provide new insights into the larval-parent interactions during brooding and development – the most crucial phase in the life-cycle of teredinids. Finally, integrative taxonomy was used to improve the taxonomic resolution of the Teredinidae and these methods helped to confirm the identity of an invasive Caribbean species of teredinid, Teredothyra dominicensis, which has recently invaded and established breeding populations in the Mediterranean Sea. This research provides the first detailed evidence that brooded L. pedicellatus larvae derive extra-embryonic nutrition from their parent. This extended parental care allows larvae to settle and metamorphose immediately after release. Development to sexual maturity is then rapid and individuals become gravid with brooded larvae within six weeks. The examination of the digestive system of L. pedicellatus using MicroCT revealed a number of adaptations towards xylotrophy. The elongated stomach, specialised digestive gland, large caecum with a well developed typhlosole and long intestine are all modifications enabling a more complete utilization of wood for nutrition. These results corresponded with the transcriptomic analysis which suggests the specialised digestive gland produces a range of cellulolytic enzymes. A phylogenetic survey of the Teredinidae using integrative taxonomy provides a robust model for future identification of species, including cryptic species, within this taxonomically challenging group. This formed the basis for the identification of T. dominicensis, a species thought to be confined to the Caribbean and Gulf of Mexico, which has recently invaded the Mediterranean. This species was found to have established a substantial breeding population in the region, which produce large quantities of larvae which could settle and metamorphose. Thus, T. dominicensis may be considered an established species in the Mediterranean. Providing a more accurate means of identification and increasing knowledge on the larval development and early life histories will help efforts to monitor the spread of teredinids and identify areas under threat from the destruction they cause. Furthermore, understanding the anatomical and molecular mechanisms which allow teredinids to deconstruct lignocellulose into monomeric sugars may provide new means of protection for wooden structures and provide novel enzymes for use in the biofuel industry.
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10

Johannsson, V. "Life history strategies of blackflies (Simulidae) in Icelandic lake-outlets." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372319.

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11

Shizuka, Daizaburo. "Parental strategies and family life of American Coots: brood parasitism, sibling rivalry, and life history /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.

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12

Pratt, Thomas C. "The impact of predation of pumpkinseed, Lepomis gibbosus, life history strategies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0002/MQ30228.pdf.

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13

Mar, Khyne U. "The demography and life history strategies of timber elephants in Myanmar." Thesis, University College London (University of London), 2002. http://discovery.ucl.ac.uk/1446021/.

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Although the Union of Myanmar is home to the second largest population of Asian elephants {Elephas maximus) in the world, the demography of its captive elephant population has never been studied before in any detail. Life history data analyzed in this thesis are taken from the records and reports archived and maintained by Myanma Timber Enterprise, which is under the charge of the Ministry of Forestry, the Government of the Union of Myanmar. The study population contains 5292 individually identified captive timber elephants, which were born or captured between 1952 and 2000. In this thesis, birth origins of timber elephants are referred to as wild-caught and captive-born. Life-table analysis indicates that the captive-born section of the population should be self-sustaining, but that the demographic rates seen in the wild-caught section would not be sufficient to maintain a stable a population. I extend my analysis by conducting detailed survival analyses. Males have a higher mortality than females throughout the age range. In adults, wild-caught elephants suffered significantly higher mortality than captive- bom elephants, and their mortality differed by capture methods. Elephants captured by immobilization showed the lowest survival rate when compared with elephants captured by either milarshikar (lasso or noose) or stockade. Regarding the causes of mortality. I document that accidents and agalactia of mothers were the primary causes of death in calves, while malnutrition and accidents were the main causes in adults. Exploring reproductive patterns and maternal investment. I find that elephant mothers do not adapt their offspring sex ratio, and that reproductive fitness is lower in wild-caught females than captive-born females. Lastly. I explore how the process of increasing time in captivity influences survival probabilities and reproductive potential in captive elephants, both within individuals and between generations. I report that capture stress causes measurable reductions in survival and fecundity rates up to 12 years after capture, as well as reducing the survivorship of calves born to captured females. To achieve a self-sustaining population of captive timber elephants in Myanmar without the need for further capture from the wild. I recommended that Myanma Timber Enterprise re-evaluates elephant management strategies, aiming to improving both the fecundity and surv ival of captive elephants in all age groups.
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14

Thomaz, Diogo Miguel Pereira Fernandes. "Alternative life-history strategies in male Atlantic salmon (Salmo salar L.)." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/34249.

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In this thesis I looked at the choice of mating tactics in male Atlantic salmon by determining the fertilisation success of individuals adopting different mating behaviours. In this species, as in most salmonids, males can either become sexually mature early in the life cycle, as small freshwater juveniles called parr, or undergo a sea migration before maturing. The alternative behaviours are thought to be contingent on environmental and social circumstances, although some researchers see them as mixed evolutionarily stable strategies. Here, using the charomid cloning method I isolated eight highly polymorphic minisatellite DNA markers and, using two that showed heterozygosities above 80%, fingerprinted more than 2,000 salmon embryos and measured for the first time the fertilisation success of mature parr and anadromous males in a wild Scottish population. The percentage of eggs fertilised by mature parr was estimated to be between 35% and 40% in this population, more than double the two previous estimates reported in semi-natural environments. In mating experiments in captivity I manipulated the number and body size of parr. Pairs of migrants were allowed to spawn in an enclosure with mature parr. Analysis of paternity revealed a strong correlation (r2=0.95) between parr size and reproductive success. The results also provided further support to a hypothesis predicting negative frequency dependent reproductive success in this species. The results in both the experiments and the field study are used to develop an optimisation model for understanding life history variation in this species. The model assumes that the choice of mating tactics is contingent on body size. General agreement between the results and observations in wild populations is taken as supportive of the important role that environment plays in male mating tactic choice in Atlantic salmon.
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15

Kobayashi, Keito. "Life-history strategies of the invasive naturalized tall bamboos in Japan." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263716.

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16

Garcia-Pena, Gabriel Ernesto. "Phylogenetic comparative analyses of breeding systems and life-history strategies in shorebirds." Thesis, University of Bath, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527144.

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17

Orton, R. A. "The life-history strategies of two species of stream-dwelling freshwater snails." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379698.

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18

Jacobs, Jerry Dale. "Regulation of life history strategies with individuals in predictable and unpredictable environments /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5169.

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19

Birget, Philip Laurent Guillaume. "Evolutionary ecology of parasites : life-history traits, phenotypic plasticity, and reproductive strategies." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28805.

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Adaptive phenotypic plasticity, the ability of a genotype to give rise to different phenotypes in different environments, evolves to allow organisms to fine-tune their life-history traits according to the varying conditions they encounter during their lives. Reproductive investment - the manner in which organisms divide their resources between survival and reproduction - is well studied in evolutionary ecology because it is a key determinant of fitness. However, whilst plasticity in reproductive effort is well understood for free-living multicellular taxa (such as insects, birds, and mammals), the application of evolutionary theory for plasticity and life history strategies to unicellular parasites and pathogens is lacking. In this thesis, I use empirical and theoretical approaches to uncover how differential resource allocation to non-replicating, sexual stages (gametocytes) versus asexually replicating stages can be harnessed by the rodent malaria parasite Plasmodium chabaudi to maximise its fitness across the often very variable conditions it encounters during infections. Differential allocation between those stages is equivalent to the fundamental life-history trade-off between survival and reproduction because gametocytes are responsible for between-host transmission (i.e. reproduction of the infection) whereas asexual parasites mediate host exploitation and within-host survival. A suite of within-host models reveal that malaria parasites could gain considerable fitness benefits in the face of low levels of drug treatment if they reduce their investment into gametocyte production ("reproductive restraint"), thereby assuring the continuity of the infection and capitalising on opportunities for future transmission. In contrast, high levels of drug treatment typically select parasites to commit all of their resources to gametocyte production ("terminal investment"), to escape a host that does not offer much opportunity for future transmission. My experiments reveal that P. chabaudi increases both its reproductive investment and its asexual replication rate in anaemic hosts (i.e. host that have a low density of red blood cells), suggesting that parasites profit from host anaemia and can afford high investment in gametocytes ("affluent investment"). I also uncover plasticity in a number of traits that underpin asexual replication rate, including invasion preference for different ages of red blood cells, but it is plasticity in the number of progeny (merozoites) per infected cell that is the main contributor to asexual replication rate. My experiments also reveal genetic variance in plasticity of the life-history traits investigated, which has profound implications for their evolution. Furthermore, plastic modification of these traits is associated with minimal costs or constraints, so that parasites can rapidly match life-history traits appropriately to the within-host environment. Severe anaemia is one of the deadliest symptoms of malaria, so observing that virulence and infectiousness increases in anaemic hosts has also fundamental clinical implications. Finally, the empirical and theoretical observations of affluent investment, reproductive restraint and terminal investment match theoretical predictions of how organisms should behave in varying environments, confirming P. chabaudi as a useful model system to test life-history theory.
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20

Löbel, Swantje. "Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes." Doctoral thesis, Uppsala universitet, Ekologisk botanik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-106847.

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The aim of this thesis was to increase knowledge about metapopulation and metacommunity processes in patchy, dynamic landscapes, using epiphytic bryophytes as a model system. Host trees and deciduous forest stands in the coniferous landscape are patchy, temporal and undergo changes in habitat quality during succession. Epiphytes must track this dynamic habitat network for their long-term survival. Community patterns at different spatial scales were explored and linked to regional metapopulation processes and local population dynamics. Spatial structuring in species richness both at a local and regional scale indicated stronger dispersal limitation but lower sensitivity to habitat quality in species with large asexual than in species with small sexual diaspores. In sexually dispersed species, a strong rescue effect was indicated by a bimodal frequency distribution of the species and by increasing local abundance with increasing patch connectivity. Present connectivity to other deciduous forest patches had positive effects on richness of asexually dispersed species, whereas richness of sexually dispersed species was instead related to the landscape connectivity 30 years ago. A study of local growth and reproduction suggested that this is caused by delayed sexual, but not asexual, reproduction. Habitat conditions affected the production of sporophytes, but not of asexual diaspores. No differences in either growth rates or competitive abilities among species with different dispersal and life-history strategies were found. In vitro experiments showed that establishment is higher from large asexual diaspores than from small sexual. Establishment of all diaspore types was limited by pH. There were indications of trade-offs between high germination and protonemal growth rates, desiccation tolerance and a rapid development of shoots from protonema. The results indicated that the epiphyte metacommunity is structured by two main trade-offs: dispersal distance (diaspore size) versus age at first reproduction, and dispersal distance versus sensitivity to habitat quality. Trade-offs in species traits may have evolved as a consequence of conflicting selection pressures imposed by habitat turnover, connectivity and irregular water supply rather than by species interactions. Syndromes of interrelated species traits imply that fairly small changes in habitat conditions can lead to distinct changes in metacommunity diversity: the results indicate that increasing distances among patches cause most harm to asexually dispersed species, whereas cuttings of forests of high age and quality as well as increasing patch dynamics are most harmful to sexually dispersed species.
Senarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:00
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21

Cutts, Christopher John. "Metabolic rate, territoriality and life-history strategies of juvenile Atlantic salmon (Salmo salar L.)." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360178.

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22

Okuda, Noboru. "Life history and sexual strategies of the cardinal fish (Pisces:Apogonidae) in the temperate sea." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/86473.

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23

Pollitt, Laura C. "Evolutionary ecology of transmission strategies in protozoan parasites." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5771.

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In recent years there has been growing interest in applying frameworks from evolutionary ecology to understand infectious disease. It is becoming increasingly apparent that the interactions between parasites within the host environment can shape parasite phenotypes underlying infection dynamics and transmission. However, the spread of the disease will crucially depend on both within-host and between-host dynamics. Bridging these scales is challenging and for vector borne parasites, such as malaria and trypanosomes, will involve gaining a much better understanding of infection dynamics both within the host and vector. I apply evolutionary ecology frameworks including social evolution, life history theory, and phenotypic plasticity to investigate how parasite phenotypes are shaped by within-host and within-vector environments and examine the implications for inhost survival and between-host transmission. Specifically, I demonstrate that; 1. Within the host; i. In accordance with theory malaria parasites detect and respond to the presence of competitors by altering reproductive strategies to maximise in-host survival. Furthermore, these strategies are fine tuned in response to variation in the within-host environment, including the availability of resources. ii. The reproductive investment strategies of malaria parasites can be applied to explain the transmission strategies of African trypanosomes. This shows how general evolutionary frameworks can be applied to a novel parasite species and demonstrates the explanatory power of an evolutionary approach. iii. The complexity of the within-host environment poses specific statistical challenges for examining the temporal dynamics of parasite life history traits that are often not adequately dealt with, potentially leading to type 1 errors. Methods to evaluate levels of autocorrelation and how to deal with it are applied to datasets of within-infection dynamics. 2. Within the vector; i. Malaria parasites undergo programmed, apoptotic cell death. The occurrence of, and putative explanation for, apoptosis in protozoan parasites is controversial. I demonstrate the importance of quantitative methods and parasite ecology in testing the evolutionary explanations for parasite apoptosis. ii. The links between within-host dynamics and within-vector dynamics are complex and can lead to counter-intuitive implications for the success of between-host transmission. Density-dependent processes result in diverse fitness costs to parasites of crowding. More broadly, these processes could explain why parasites undergo apoptosis. In general my results demonstrate, across vertebrate hosts and insect vectors, how the interactions between parasites and with their environment shapes traits important for the transmission of infectious disease.
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Lord, Joshua Pratt 1986. "Modeling of Life History Strategies in Organisms with Indeterminate Growth, with a Focus on the Distribution and Life History of the Gumboot Chiton Cryptochiton stelleri." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10827.

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xii, 148 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
The gumboot chiton Cryptochiton stelleri is the largest intertidal invertebrate herbivore on rocky shores in the Pacific Northwest. This study documented the larval development, metamorphosis, distribution and life history of this species. Growth rings in valves of Cryptochiton stelleri and Katharina tunicata were used to determine age and showed life spans of at least 40 years for C. stelleri and 17 years for K. tunicata. Field surveys in southern Oregon showed that C. stelleri populations are densest in small coves as a result of mortality, food availability, or larval retention. Growth curves based on length, weight and volume were created for several intertidal invertebrates. When incorporated into energy allocation models, length-based curves can underestimate growth and exaggerate an energetic shift from growth to reproduction. Estimates of food intake and reproductive output showed that continuous growth leads to higher food intake and increased fecundity in several organisms with indeterminate growth.
Committee in Charge: Dr. Alan L. Shanks, Chair; Dr. Cynthia D. Trowbridge; Dr. Richard B. Emlet
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Bongard, Terje. "Life history strategies, mate choice, and parental investment among Norwegians over a 300-year period." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-802.

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In this thesis, seven papers concerning life history, mate choice and parental investment strategies are presented. Data was compiled from old church books from two parishes in Central Norway from 1700-1900, Soknedal and Smøla (Paper I-IV). Also the results of three questionnaires are presented (Paper V-VII). Results show that access to stable resources was the main predictor of number of children born and number of grandchildren produced within and between two human populations (Paper I). The two studied villages (Soknedal and Smøla) were at the same latitude, but had different resource foundation in that the coastal parish (Smøla) had access to year round fishing. This extra resource affected most life history traits of particularly low class women, who produced significantly more grandchildren than their sisters without this stable resource. Birth rank and family size also affected the life history of children (Paper II). Here we considered the survival rate, the probabilities of becoming married and migration rate from the home parish in relation to status of mother, family size, sex of the children, birth rank, sex ratio of siblings, year of birth and age of the mother. We found that the future reproductive value of boys was greatly affected by both family size and birth rank, in that boys from larger families and boys late in birth rank had a lower probability of getting married and a higher probability of migrating from the parish. No such relations were found for girls. We conclude that a difference in the access to parental resources during childhood affected the life history of boys, but not that of girls.

There was no support for longer birth intervals between the births of two boys compared to other sex combinations of children (Paper III). Short birth intervals (less than two years) between two children led to higher mortality among both the first-born and second-born in such combinations There were significant differences in birth interval between high and low status women in both parishes. Also the poorer parish of Soknedal had longer birth intervals than Smøla for both status groups. The survival rate increased significantly when birth intervals exceeded 2 years, both for a child and its next sibling. The optimal birth rate in Soknedal seems to be slightly over three years. In a multilinear regression analysis, the number of children of mother was, not surprisingly, the most important variable in explaining the variation in birth interval. Laterborn children had longer birth intervals (Paper III).

In Paper IV we tested the inbreeding avoidance between related individuals in Soknedal parish, and found this to be significant. We found, however, no statistically significant differences in fertility between the three groups called non-locally, consanguineous and locally married couples.

Physical variables in human mate choice were tested on a sample of students (Paper V). There was a significant correlation between the age of a man and a woman and the height of the two individuals in a pair. However, none of the correlations or cross-correlations between height, weight, hair colour or eye colour were statistically significant. Within a pair there was a highly significant positive correlation between the attractiveness of a man and a woman. We also tested if strangers could pick out mates by facial looks. 101 test persons were presented a series of four photos, two males and two females and asked to pick out the pair. The pair was correctly picked out in about 40 % of the cases, which was higher than random. Altogether almost 90 percent of the test persons were able to pick out the pair more frequently than random. There was no significant difference between the sexes in their ability to pick out the right pair from photos. Paper VI presents results concerning female view of the male commitment into a relationship, his economic status variables and his ambition levels. We tested predictions derived from evolutionary biology concerning female mate choice through a questionnaire presented to female subscribers of a Norwegian magazine. The expectations of a stable economic wealth prior to engagement affected positively the length of relationships. The partner's economic stability, the respondent's perceived economic satisfaction and the partner’s investment in children from previous relationships were significantly higher in an ongoing than in a broken relationship. These factors are predicted to be crucial to mate choice and ultimately fitness-enhancing. Finally, in Paper VII phenotypic levels of daily-life parental-offspring conflicts in two different social contexts were studied; 1) between biological parents and their offspring at home, and 2) between the adults and the same children in the nursery school. Parents and nursery school teachers were asked how the children acted in conflicting situations that frequently occur during a day. Parents reported a higher level of conflict with their children than did teachers from nursery schools. Parents did not experience differences in conflict level between boys and girls, while nursery school teachers did experience such differences. The results give support for the hypothesis that children have an innate and selected mechanism that guides them in different social contexts, and that they easily assess differences important for the level of care and attention they can expect to get. Children expect a higher investment from their parents than from their teachers, and therefore solicit more in the parent-offspring context. Such context-related behaviour among children will optimise their own social status and benefits in the form of resources and attention, and is the conceptual background for parent-offspring conflict.


Denne doktoravhandlingen består av syv arbeider innenfor feltet human atferdsøkologi. I motsetning til sosiologisk tilnærming forsøker humanbiologien å finne universelle trekk som er like for alle. Medfødte trekk trenger ofte en utløsende miljøfaktor. Poenget er imidlertid at på et evolusjonært grunnlag følger det logisk å tro at alle individer vil respondere mer eller mindre likt. I forhold til noen atferdstrekk er dette lett å vise, som for eksempel smerte, latter, sjalusi eller sinne. Andre trekk kan bare testes statistisk, som for eksempel at barn maser mer på foreldrene sine enn på andre voksne, eller at trangen til å emigrere er større når en gutt fødes sent i fødselsrekka, slik jeg har vist her.

De fire første arbeidene er analyser av data fra kirkebøker fra Soknedal og Smøla mellom 1700-1900. De tre siste er resultater fra tre spørreundersøkelser foretatt i årene 1993- 2002. Soknedal og Smøla har en biologisk relevant ulikhet i at Smølaboerne hadde tilgang på fiske året rundt, noe som stabiliserte mattilgangen. Denne ulikheten ga seg utslag i at lavstatuskvinner fra Smøla fikk flere barnebarn enn lavstatuskvinner fra Soknedal (Paper I). Blant høystatuskvinner var det ingen forskjell. Størrelsen på søskenflokken og nummer i fødselsrekkefølgen bestemte viktige livshistorieparametre (Paper II). Kjønnsforskjellene var store og ga seg utslag i at en senerefødt gutt hadde lavere sjanse for å overleve, lavere sjanse for å bli gift, men høyere sannsynlighet for å emigrere. Slik var det ikke for jentene. Dette er i tråd med seleksjonsprinsippene for arter med høy foreldreinvestering ved at tidligfødte menn som arvet mest ressurser ble attraktive og fikk livsløp med større sjanser for etterkommere. Også fødselsintervallene betyr mye for livsløpet (Paper III). For korte mellomrom mellom fødslene gir lavere ressurstilgang til barna (både det som er født før og etter) og dermed lavere fitness, men samtidig bør total reproduktiv periode utnyttes. Dermed kan det beregnes et optimalt fødselsintervall som gir flest overlevende og attraktive etterkommere. Det finnes noe data på at det å få gutter er mer ressurskrevende, og vil øke det optimale intervallet, men materialet fra Midt-Norge viste ikke dette. I Paper IV så jeg på om beslektede individer unngikk å gifte seg med hverandre, hvilket de gjorde. Sannsynligheten for å gifte seg med en slektning var ganske stor på den tiden (24 %), men bare 9 % av høystatus- og 6 % av lavstatuskvinnene giftet seg med slektninger. Partnervalg er et område det er gjort ganske mye forskning på, og vi gjentok en del av de undersøkelsene som viser at vi ofte velger partnere som matcher oss i fysiske variabler (Paper V). Vi fant bare korrelasjon mellom alder og høyde, og ikke mellom høyde, vekt, hårfarge eller øyefarge. Vi fant en god korrelasjon i skjønnhetsscore. Vi la ut foto av to menn og to kvinner og lot ti personer velge ut hvem som var sammen av disse. Tilfeldig ville 25 % velge riktig, men forsøkspersonene klarte nesten 40 % rett. Dette støtter hypotesen om at vi ser etter tegn og trekk som er relevante for hvor attraktive vi er, og at dette er en universell egenskap hos mennesker. Disse egenskapene trenger ikke være fysisk utseende, men kan være atferdstrekk forbundet med omsorgsevne og økonomi. Bladet ”KK” betalte for en spørreundersøkelse blant sine abonnenter hvor vi blant annet spurte om økonomi, ambisjoner og innsats hos tidligere og nåværende mannlige partnere (Paper VI). Det var god korrelasjon mellom utilfredsstillende økonomi, manglende innsats og omsorg, lavt ambisjonsnivå og graden av skilsmisse og brudd i forholdene. Menn som viste ambisjoner, hadde felles økonomi, investerte i kvinnens tidligere barn og hadde økning i inntekt, ble sjeldnere skilt. Et interessant resultat var at menn som ble karakterisert som svært ambisiøse hadde økt sjanse for brudd med partneren. Dette kan ha flere grunner, hvorav to er nærliggende: 1) En overinvestering i karriere må nødvendigvis ta tid og krefter, og det vil gå utover investeringen i hjemmet. Her er det viktig å huske at det er den følelsesmessige reaksjonen hos partner som er viktig, og ikke nødvendigvis antall kroner som teller. 2) Menn med karriere er attraktive, og vil få flere tilbud og muligheter for andre partnere. I den siste undersøkelsen kartla vi ulikheter i hvordan biologiske foreldre og barnehageansatte oppfatter konflikter med barn (Paper VII). Ut fra evolusjonær biologi kan en predisere at barn vil være tilpasset å kreve mer av sine foreldre enn av andre voksne, og at dette vil gi seg utslag i et høyere konfliktnivå med det samme barnet, avhengig av hvem som i øyeblikket har omsorgen. Vi fant støtte for prediksjonen ved at i alle de undersøkte situasjonene med det samme barnet oppfattet den biologiske forelderen et høyere konfliktnivå enn den barnehageansatte.

Det er utgitt en svært omfattende bok på norsk som oppsummerer hva som er oppnådd hittil innen fagretningene sprunget ut av evolusjonær biologi (Mysterud, 2003). Boken anbefales til alle som arbeider med mennesker på alle plan. Evolusjonsbiologi er en del av naturvitenskapen, og er dermed logisk sammenhengende på en annen måte enn samfunnsvitenskapene. Evolusjonsbiologi er grunnleggende konsistent og sammenhengende med hele den menneskelige vitenskap, og det er derfor ikke logisk eller rasjonelt å velge å se bort fra de problematiske sidene av denne forskningen.

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26

Evanson, Melissa. "Chinook salmon population dynamics and life history strategies in the Squamish River Watershed, BC, Canada." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1722403321&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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27

Walker, Alan Melville. "Life history strategies in anadromous trout, Salmo trutta L., with special reference to osmoregulatory physiology." Thesis, University of St Andrews, 1998. http://hdl.handle.net/10023/15003.

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1. Juvenile trout, Salmo trutta L., from three parental groups - sympatric Sea trout and freshwater-Resident trout, and isolated trout from above a waterfall impassable by upstream migrating anadromous trout - were reared under three ration regimes to manipulate growth rates. The development of seawater tolerance was studied by measuring drinking rates after periodic salinity challenges during the first two years of juvenile growth. No trout were observed to undergo the parr-smolt transformation in any of the parental form/ration combinations after two years in freshwater. However, a considerable proportion did mature during this time period. The proportion of maturing trout was directly related to ration level but was also influenced by parental form, with isolated trout demonstrating a greater tendency to mature early. Seawater tolerance increased with age in all groups. However, mean drinking rates upon salinity challenge were generally lower, from Experiment 2 onwards, in Resident trout than in either of the other two groups. 2. Eight immature sea trout (finnock) were radiotracked in the River Eden, Fife, during September, October and November 1994. The individual finnock displayed considerable variation in patterns of movement; two remained in freshwater for at least 27 days whereas others moved downstream out of the river within days or even hours of release. In general, this highlighted the transient nature of the freshwater migrations of some finnock, indicating that they move in and out of rivers over brief periods of time and apparently do not necessarily remain in freshwater continuously throughout the winter. 3. The hypo-osmoregulatory ability of finnock during the winter was assessed in two experiments. The number of finnock was limited in Experiment 1. Therefore, this was designed as a preliminary assessment of the physiological response of finnock to acute freshwater-seawater transfer. Osmoregulatory abilities were assessed by measurement of drinking rates, plasma ion and plasma cortisol concentrations after acute freshwater-seawater challenge and compared with freshwater-adapted and seawater-adapted control groups. Finnock displayed physiological responses typical of euryhaline teleosts upon seawater challenge; a rapid increase in drinking rate, an increase in plasma ion concentrations (but only to levels similar to, or slightly greater than, those of seawater-adapted fish), and increased plasma cortisol concentrations. The second experiment, in which numbers of finnock were greater, made use of the same techniques to assess the longer term acclimation of finnock to both freshwater-seawater and seawater- vi freshwater challenge, to establish whether finnock might suffer from a more subtle reduction in seawater-tolerance which would not have been necessarily apparent in the acute challenge of Experiment 1. Finnock did not appear to be physiologically compromised by seawater challenge during the winter months, and therefore, a breakdown in hypo-osmoregulatory abilities alone cannot be considered a reason for finnock returning to estuaries and rivers during the winter. 4. The physiological effects of low to medium levels of infestation of the ectoparasitic copepod Lepeophtheirus salmonis (Kroyer) on wild sea trout post-smolts were assessed at intervals during the development of the parasite. A mean infestation level of 18 parasites caused significant disruption to the osmoregulatory ability of hosts, as demonstrated by significantly higher plasma osmolality and chloride ion concentrations when compared with naive post-smolts. In addition, since no skin lesions were apparent on the hosts, these physiological effects were considered to be the consequence of larval attachment to the gill filaments, thereby possibly puncturing the epithelia and also damaging vital branchial ion excretory cells. 5. The modern molecular genetic RAPD-PCR technique was used to screen DNA of Lepeophtheirus salmonis collected from wild and fanned salmonid hosts from around the Scottish coasts. This technique indicated markedly different patterns of genetic variation amongst L. salmonis of farmed and wild origin, and between different farms. A number of genetic markers were found to be exclusive to, or at considerably higher frequency amongst, sea lice collected from farmed salmonid hosts. This technique established the possibility of assigning provenance to L. salmonis collected from wild hosts.
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Stanton, Samuel Andrew. "Structure and function of the external ciliation of larval bivalves with different life history strategies." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/structure-and-function-of-the-external-ciliation-of-larval-bivalves-with-different-life-history-strategies(7cd70842-de3a-4e51-93a1-b3578c45861b).html.

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Cilia are of particular importance to the planktonic veliger larva, fulfilling feeding, locomotory and sensory roles. This study concentrates on the ciliation of the larval mantle and velum. The mantle is an important adult organ yet one scarcely studied in the larval form. The larval velum is the characteristic swimming and feeding organ of the veliger larval form. Knowledge of the ciliary arrangement of larval bivalves, especially in relation to different life history strategies, provides important information for arguments over the phylogeny of such characteristics within the Mollusca. Anatomical work explored the possibility of ciliary sense organs being found on the mantle and further elucidates the pattern of distribution of cilia on the velum. Larval ciliary swimming in varying water temperatures has been investigated via the development of a filming methodology, revealing the thermal tolerance of swimming using velar ciliation and the ability of the larva to detect and respond to temperature stimuli. Cilia were investigated throughout larval development from veliger stage to metamorphosis in two bivalve families, the Ostreidae (Crassostrea gigas and Ostrea edulis) and the Teredinidae (Lyrodus pedicellatus). The three larvae represented three developmental modes with C. gigas planktonic, O. edulis partly brooded and L. pedicellatus long-term brooded. Scanning electron microscopy (SEM) and light microscopy was used for anatomical investigations. Confocal laser scanning microscopy was used to locate catecholamines and serotonin in C. gigas larvae, with reference to the cilia locations identified by SEM. Swimming larvae were filmed in fixed and changing temperatures to identify behavioural or physiological reactions. The mantle of the ostreid larvae had 13 different cilia groups which have been identified and photographed in C. gigas and O. edulis. Two of these groups appear to be sensory. One group is associated with the developing gill bud, and the other is located directly under the posterodorsal shell notch. The location of this group under the shell notch also was the location for several cells containing catecholamines. The ventral inner mantle rim of ostreid larvae has large tracts of cilia, probably primitive larval versions of adult rejection tracts. There were several flask-shaped cells with catecholamines and two long serotonin containing fibres in the mantle where these tracts were found. The mantle of L. pedicellatus had 2 distinct groups of cilia. One of these groups formed discrete clumps on the inner mantle fold and featured sensory structures. The velar ciliation of both the ostreid species larvae was almost identical, and both revealed a previously unreported band of cilia. This band may increase the efficiency of the opposed band particle capture system. The velum of L. pedicellatus was different from the ostreid larvae; its velar ciliature was similar to other long-term brooded larvae recorded in the literature with a large adoral tract and the loss of the post-oral band. Larval swimming velocity increased with increasing water temperature. Acclimated larvae were able to swim in water temperatures where larval activity stopped during sudden temperature changes. Changes in larval swimming during sudden temperature changes are probably due to an interaction of three factors: water viscosity changes affecting cilia efficiency, the physiological effect of temperature and behavioural responses. The additional ciliary band on the ostreid velum probably increases particle capture efficiency, and further investigations are needed to determine if this is a characteristic unique to the ostreids. The velar ciliation of the brooded L. pedicellatus is, by the pediveliger stage, similarly modified to the velum of other brooded larvae from widely separated taxonomic groups. Mantle ciliation is more extensive in ostreids than in teredinids, but both have sensory stereocilia on the mantle. The presence of catecholamines and serotonin suggests that the larva has a measure of control both of mantle and velar ciliary beat, seen in the variation in swimming patterns and particle rejection. The filming and analytical techniques developed offer an accessible method for gathering laboratory data on larval behaviours. Analysis of swimming suggested larvae can sense changes in temperature and effect a behavioural response to it. Such responses may enable larvae to control their vertical position in the water column when encountering environmental discontinuities or heterogeneities such as thermoclines. Variation in larval swimming velocity between larval batches suggests this method could also be used as a quick assay to determine the fitness of different larval batches within a hatchery.
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29

Jackson, Jenee James. "Sociosexual Development: Infusing the Belsky, Steinberg, and Draper Model with Sexual Selection." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196156.

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Life history theory attempts to explain between- and within-species variation in maturational and reproductive patterns, whereas sexual selection attempts to explain between- and within-sex differences in intersexual mate choice and intrasexual competition for members of the opposite sex. These two expansive evolutionary theories have been used by developmental scientists and social/personality psychologists to explain the variation observed in human reproduction, including the timing of reproductive events and individual differences in orientation toward mating and parenting. In Part I of the following paper, I review research related to life history theory and sexual selection in humans. I then show how integrating the principles of sexual selection with life history models of human reproductive strategies can address existing limitations. In Part II, I empirically examine many of the unique propositions that emerge from theoretical integration using a longitudinal dataset on adolescent development. Under investigation is an expanded model of sociosexual development that incorporates key principles from Belsky, Steinberg, and Draper's (BSD) psychosocial theory and sexual selection theory. I specifically examine the role of early rearing conditions within the home, as specified by BSD, and self-perceived mate value, as highlighted by a sexual selection perspective, on timing of sexual debut and sexual risk taking. The current study combines variable-centered and person-centered methods to assess specialized developmental trajectories. In total, the study provides novel support for BSD theory, while also highlighting needed revisions to account for the role of self-perceived mate value on adolescent sexual behavior.
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Easton, Lyndlee Carol, and lyndlee easton@flinders edu au. "LIFE HISTORY STRATEGIES OF AUSTRALIAN SPECIES OF THE HALOPHYTE AND ARID ZONE GENUS FRANKENIA L. (FRANKENIACEAE)." Flinders University. Biological Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081124.105244.

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This thesis is a comparative study of the life history strategies, and in particular seed germination requirements, in Australian species of the halophyte plant genus Frankenia L. (Frankeniaceae). Frankenia is a cosmopolitan genus that occurs in Mediterranean, semi-arid, and arid regions on distinctive soil types – commonly on saline, sodic or gypseous soils – in habitats such as coastal cliffs, and on the margins of salt lakes, salt-pans and saltmarshes (Summerhayes 1930; Barnsley 1982). The plants are small shrubs or cushion-bushes with pink, white or pale purple flowers, and salt-encrusted recurved leaves. This project investigates germination requirements for Frankenia in relation to seed age, light requirements, temperature preferences, salinity tolerance, and soil characteristics. It also explores two divergent reproductive strategies – notably seed packaging strategies – in relation to environmental variables. Within the 46 currently recognized endemic Australia species, some species have a few ovules per flower and produce only a few larger seeds per fruit, while other species have many ovules per flower and produce many small seeds per fruit. Large-seededness is thought to increase the probability of successful seedling establishment in drought and salt-stressed environments. As both larger- and smaller-seeded species of Frankenia co-occur in close geographical proximity, hypotheses regarding the advantages of large-seededness in stress environments can be tested. By restricting the analysis of seed mass variation to similar habitats and within a single plant genus, it is possible to test ecological correlates that would otherwise be masked by the strong effects of habitat differences and phylogenetic constraints. Overall, larger-seeded Frankenia species were demonstrated to be advantageous for rapid germination after transitory water availability, and for providing resources to seedlings if resources became limiting before their successful establishment. Smaller-seeded species delayed germination until both soil-water availability and cooler temperatures persisted over a longer time period, improving chances of successful establishment for the more slowly growing seedlings that are more reliant on their surroundings for resources. This study produces information on the seed and seedling biology of many Australian species of Frankenia including several that are of conservation significance, e.g. F. crispa with its isolated populations, and the rare and endangered F. plicata. This information is important for the development of conservation management plans for these and other arid zone, halophyte species. In addition, the results of this study are of practical significance in determining the suitability of Frankenia for inclusion in salinity remediation and mine-site rehabilitation projects, and for promoting Frankenia as a drought and salt tolerant garden plant.
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31

Pullin, A. S. "Life history strategies of the butterflies, Inachis io and Aglais urticae, feeding on nettle, Urtica dioica." Thesis, Oxford Brookes University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370503.

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32

Suwandy, Jason. "Temporal Currency: Life-history strategies of a native marine invertebrate increasingly exposed to urbanisation and invasion." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/7322.

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Biological invasions pose a serious threat to biodiversity world-wide. Through various means, such as competition or predation, invaders can radically change species composition and the functioning of native ecosystems. Even though our understanding of the mechanisms underlying invasion success is improving, there is still a lack of knowledge on the response of native species under pressure from invasion. This study adds to existing knowledge on the responses of a native species to invasion by non-indigenous species. Pyura pachydermatina is a native ascidian in the southeast coast of New Zealand currently under pressure from increased urbanisation and invasion by other ascidian species. The reproductive strategies employed by P. pachydermatina are investigated and the role of these strategies to increase its resistance to invasion are assessed. A population study on the status of P. pachydermatina around the Banks Peninsula was carried out in Camp Bay, Pigeon Bay, and Wainui. Spawning experiments using P. pachydermatina and gonad histology were done regularly during the one year study period to assess its ability to self-fertilise and determine its reproductive period. In addition, predation experiments were carried out to assess the susceptibility of P. pachydermatina early life stages to two amphipod predators. The surveys indicated that the populations of P. pachydermatina in the three sites are different from one another. Wainui has on average the largest individuals of P. pachydermatina and Camp Bay, the smallest. Abundance of P. pachydermatina was highest in Pigeon Bay and lowest in Wainui. The three life stages of Pyura pachydermatina; recruits, juveniles, and adults, were present in all sites at all seasons. The spawning experiments confirmed the species’ ability to self-fertilise and that it has a year-round spawning period. The two amphipod predators, Jassa marmorata and Caprella mutica, were efficient in consuming the egg and larval stages of P. pachydermatina, but did not feed on the settlers. Year-round reproduction and the ability to self-fertilise potentially give P. pachydermatina increased resistance to the effects of urbanisation and invasion. This population study suggested that the species is thriving around the Banks Peninsula. This, combined with previous studies on the non-indigenous ascidian Styela clava that stated the static or declining populations of the potential invaders, gives a positive outlook for the native species for the future. I suggest the use of genetic techniques to assess, in more detail, the population structure and dispersal potential of this native species. I also suggest constant monitoring of native species is required to keep up to date with the current status of the species, which will in turn help management decisions should regional spread of the Lyttelton S. clava invasion occur in the future.
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33

Hughes, Martin Robert. "What makes a ferox? : the drivers & consequences of alternative life history strategies in S. trutta." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8280/.

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34

Starling, Amanda. "Behavioural plasticity of life history traits in the New Zealand avifauna." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1327.

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The purpose of this research was to determine how predator control influences nest survival and changes in life history strategies of birds. All studies were conducted at two sites: one site had very little mammal control, while the other site is a 'mainland island' in which all introduced mammals were trapped or poisoned. Nest survival rates of introduced and native species were compared between the two sites by locating and monitoring nests of nine species. I found that mammalian predator control increased nest survival rates of both introduced and native species, but the incrase of nest survival was more pronounced in native species. The influence of predator control on the plasticity of life history strategies in introduced and native New Zealand birds was also examined. Some life history strategies (e.g. time spent incubating, frequency of visits to the nest) changed significantly in the area with predator control, while other life history traits (e.g. clutch size) did not vary between areas. I found that both introduced and native New Zealand birds changed a variety of life history traits and that the changes were likely a plastic response to the recent change in predator numbers. As it has been suggested that birds may become less responsive to mammals when predators are controlled, I tested the response of birds to a model of a feral cat. Birds in the predator control area were significantly less likely to recognise the cat model as a potential threat. This suggests the recognition of predators can be rapidly lost from a population. My research confirms that mammal control can increase nest success of native species, but reductions in predator numbers can also change a variety of life history traits and behaviours. As the removal of mammalian predators also appears to make birds less responsive to potential predators, it is important for continued mammalian control once management has begun. Otherwise, any reintroduction of predatory mammals into controlled sites would likely place such bird populations at greater risk as they would have behaviours suited to an environment with lowered nest predation risk.
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Bradford, Michael J. "The role of environmental heterogeneity in the evolution of life history strategies of the striped ground cricket /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70319.

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I examined the effect of heterogeneity in the thermal environment on the life history of the cricket Allonemobius fasciatus. Variation in the life cycle was the result of a mixture of phenotypic plasticity and genetic differentiation in phenology-related traits along a latitudinal cline in growing season. Females from a partially bivoltine population have a conditional life history because they can adjust the proportion of diapause eggs in accordance with the likelihood that a second generation will grow and reproduce before winter. The thermal environment is not variable enough to result in the evolution of a marked bet hedging response, as is predicted by theory. A quantitative genetic analysis of the diapause reaction norm revealed significant heritabilities as well as correlations with other traits that could be related to common physiological mechanisms.
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36

Clauss, Maria Johanna. "Life history strategies in variable environments: Demography, delayed germination and bet-hedging in a desert annual Plantago." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/282885.

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Temporal variability in the environment can affect population dynamics and life history strategies. Annual plants in desert environments are subject to large fluctuations in precipitation, both within and among years. I used a combination of field and laboratory studies to characterize variability in the populations dynamics and life history of a desert winter annual plant. I conducted demographic studies over four seasons in four populations of Plantago insularis Eastw. [Plantaginaceae] located along a precipitation gradient in the Sonoran Desert. I quantified the fates of germinated and non-germinated individuals by monitoring permanent quadrats and repeatedly sampling the soil seed bank. A fraction of seeds in all populations delayed germination and formed a persistent seed bank. Populations with more among-year variation in precipitation had greater variability in reproductive success for germinated seedlings, and the population in the most xeric environment was the most variable. Survival of non-germinated seeds was less variable than reproductive success of germinated seeds in all populations. Thus, non-germinating seeds reduced temporal variation in population dynamics by increasing population growth in dry years and decreasing growth in wet years. In this field study, populations in historically more xeric environments had lower mean germination fractions. Using geometric mean growth rate as an estimate of fitness, I demonstrate that germination fractions less than one were adaptive in three of four populations. Results of experimental studies with up to twelve populations of P. insularis, suggest that field germination responses emerged from a combination of two processes. Lower water availability during germination resulted in lower germination fractions. When water was amply available, all populations could express high germination fractions. A pattern of delayed germination consistent with bet-hedging as an adaptation to temporal variability in reproductive success arose in the field, in part, because frequencies of wet and dry germination conditions differed among populations. Phenotypic plasticity in germination response for seeds in the most xeric, environment conferred greater fitness than would have been possible with any one constant germination fraction.
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37

Volpe, Lane Elizabeth. "Using life-history theory to evaluate the nighttime parenting strategies of first-time adolescent and adult mothers." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/287/.

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This study explores the nighttime parenting behaviour of first-time adolescent and adult mothers. Two theoretical approaches are evaluated. The first model suggests that differences in parenting behaviour between teens and adults occur because teen mothers are less well-prepared for nighttime infant care compared to more mature mothers. The second draws on evolutionary theory and suggests that nighttime parenting figures into the suite of behaviours that comprise parental investment, which varies depending on the life-history trajectories and reproductive strategies of individual mothers. The project addresses how understanding nighttime parenting behaviour as part of an individual‘s life-history trajectory can inform public health policies and interventions related to infant sleep. Methods A sub-sample of adolescent and adult mothers was drawn from a larger, prospective longitudinal study on transition to parenting in Indiana, U.S.A. Overnight, infra-red video recordings of the nighttime parenting behaviours of mother-infant dyads were collected for 23 adolescent and 22 adult mothers when infants were approximately 4 months of age. The video recordings were reviewed in real time in their entirety and coded using a behavioural taxonomy designed for this study which was entered into the Noldus Observer software. Data were analysed for group differences and were assessed against the predictions derived from the two models to determine which theoretical framework better fit the behavioural outcomes. Additionally, qualitative descriptions of focal behaviours related to infant risk were produced. Results Teen mothers exhibited closer physical proximity while infants were awake and asleep, mother-infant bedsharing, and a higher number of sleep environments for infants. There was more compatibility between maternal and infant sleep periods in the teen group, with mothers going to sleep sooner after their infants did compared to adults. There was also a trend toward teen mothers having more frequent but shorter awakenings during the night. Adults spent more time at greater distances from their infants, and more often placed infants to sleep in a cot in a separate bedroom. Both groups were prompt to respond to infant crying, although there was a trend towards shorter crying bouts among infants of teen mothers. Fewer teen mothers breastfed their infants, and infant self-feeding from bottles propped on blankets or other materials was more frequent among teen mothers. There was a trend towards more frequent placement of infants in the prone sleeping position among the teen mothers, although intervention by research staff in such instances obscured the outcomes. More teen mothers placed their infants' heads on pillows compared to adult mothers, but for the major categories of risk that were coded (breathing risks, feeding risks, and other types of potential risk) there were no group differences between teens and adult. Conclusions The findings of this study revealed significant differences between teen and adult mothers in how they managed the costs of caring for infants at night. The predictions generated by the life-history model were a better fit for the behavioural outcomes overall. Life-history theory predicted that teens would engage in cost-reducing measures in order to meet their own growth and development needs as well as those of their infants while adult mothers could afford to exhibit greater parental investment relative to self-investment. Teen cost-cutting measures were evident, and were accomplished by pursuing a behavioural strategy that minimised parent-infant conflict and brought maternal and infant needs in line with each other during the night. The teen strategy achieved a reduction in maternal costs through increased involvement with and proximity to infants, rather than through the withdrawal and distancing that would be predicted by existing literature on the sub-optimal parenting styles of adolescents. The conventional model suggested that the sub-optimal parenting style of adolescents would lead to greater sleep-related risk exposure. However, the data revealed that risks occurred for both groups, although they involved different sleep environments. Implications The findings of this study also contradict the assumption that any sleep environment is inherently safe or inherently risky, and suggests ways in which an evolutionary perspective might be applied to modifying public health policy related to infant sleep. The findings reinforce the idea that parental behaviour affects the risks to which infants are exposed and that nighttime parenting behaviours are shaped by maternal reproductive and parental investment strategies. This study therefore supports the idea that one-size-fits-all approaches to health and behaviour are inappropriate, and that public health recommendations related to infant sleep should be sufficiently elastic and/or tailored to allow for the range of contexts within which infant care occurs. Because mothers arrive at parenting from very different life trajectories, and because each of these trajectories causes them to evaluate and tolerate parenting costs and risks to infants in variable ways, it is incongruous to expect that they should all be encouraged to parent in a similar manner or to structure their infants‘ nighttime routines in a uniform way.
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38

De, Waal Caroli. "Dispersal, dormancy, life history and breeding systems of southern African Asteraceae : risk-reducing strategies in unpredictable environments." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96736.

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Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: How organisms respond to unpredictable environments is a fundamental question in evolutionary ecology. For example, plants may reduce the risk of reproductive failure by spreading their reproductive effort in space (dispersal) or in time (dormancy, iteroparity). Similarly, different plant breeding systems, (for example the ability to autonomously self-fertilise) may reduce the risk of reproductive failure in environments where pollination in particular is unreliable. Each of these strategies may be affected by selective pressures exerted by heterogeneous abiotic and biotic environments (e.g. unreliable rainfall patterns or range edge habitats). However, there is little theoretical or empirical consensus on how these strategies are related. In Chapter 2, I explore the association between dispersal and breeding system traits and range edge proximity. I show that annual daisies from Namaqualand, South Africa, are characterised by two discreet syndromes: high selfing ability associated with good dispersal and obligate outcrossing associated with lower dispersal, regardless of range position. This chapter illustrates that selection on both breeding system and dispersal traits may act consistently across distribution ranges. Because co-flowering plants often share pollinators, their fecundity is likely affected by changes in pollinator visitation rates or the transfer of conspecific relative to heterospecific pollen. In Chapter 3 I experimentally investigate the effects of con- and heterospecific density and spatial distribution pattern on pollination and fecundity in annual Namaqualand daisies. I show that increasing conspecific density and aggregation enhanced fecundity through increased mate availability and reduced heterospecific interference, independent of pollinator visitation rates. Moreover, I demonstrate the benefits of autonomous selfing when mates are limited and the potential for interspecific pollen transfer is high. In Chapter 4, I examine relative investment in dispersal vs. dormancy in seed heteromorphic Dimorphotheca (Asteraceae) species in relation to life history, rainfall unpredictability and range edge proximity. I show annuals and perennials differ significantly in the relative investment in different dispersal strategies. However, my findings provide little support for theoretical predictions of bet-hedging strategies in unpredictable or range edge habitats. This chapter emphasises the role of local environmental factors on fruit set that may obscure expected patterns across broad climatic gradients. Because of different costs and benefits of dispersal in space and time, we may expect negative patterns of covariation among dispersal and dormancy as alternative risk-reducing strategies. In Chapter 5, I provide evidence for a trade-off between these traits across 27 wind- dispersed daisy species from South Africa. This trade-off did not depend on life history effects, but was inconsistent at different levels of biological organisation. I also show that the effects of life history on spatial and temporal dispersal were inconsistent. Taken together, my research illustrates the importance of simultaneously investigating different risk-reducing strategies, because associations among them are clearly complex and often contradict theoretical expectations. Moreover I show that the effects of life history and phylogenetic relatedness cannot be disregarded. My findings underscore the importance of dispersal in space and time as well as autonomous selfing as risk-reducing responses to unreliable environments.
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39

Hülsmann, Stephan. "Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1060170274484-94614.

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The population dynamics and demography of Daphnia galeata was analysed in a five year study in the biomanipulated Bautzen Reservoir. Samples were taken two times a week during the period May-July in the pelagic zone of this highly eutrophic water. Major bottom-up and top-down factors were determined during the study period and analysed with regard to their influence on Daphnia dynamics and life history. Field data on fecundity and population structure of D. galeata were combined with results from life table and growth experiments performed under approximately in situ conditions to gain insight into the mechanisms leading to a midsummer decline of this cladoceran species which dominates the zooplankton community in Bautzen Reservoir. Two main patterns of Daphnia dynamics emerged: In years without a midsummer decline the population increased slowly in spring, starting from low densities. High water transparency was observed already during the build-up of the population of D. galeata. Despite considerable fluctuations, Daphnia abundance remained on a high level throughout summer. In years with a midsummer decline the population started from relatively high densities in early May and more than doubled during one week. Peak densities were reached before the clear-water stage emerged. At the end of this period the population declined to low values which lasted for the rest of the summer. Fecundity of the Population of D. galeata declined, whereas the mean egg volume increased at the beginning of the clear-water stage as a result of declining food levels. The size at maturity (SAM) remained high during this period. Additionally, juvenile growth was reduced and the age at maturity was retarded. Survival probability was low for those daphnids born shortly before or during the clear-water stage compared to those born later. It can be concluded from these results that recruitment to adult stages is strongly reduced during the clear-water stage. The end of this period is marked by an alternation in generations. Only at that time can SAM be reduced because the new generation of adults matures at a smaller size, carrying small eggs. A high impact of non-predatory adult mortality can be expected when the population is dominated by a strong peak-cohort during the clear-water stage according to recruitment patterns during the build-up of the population. The most drastic decline both of Daphnia abundance and SAM was observed in those years when the biomass of juvenile fish exceeded 20 kg ha-1 at the end of the clear-water stage. Due to gape-size limitation juvenile fish mainly feed on juvenile daphnids during this period and thus, they reinforce bottom-up effects on the Daphnia population. When fish change their size selection towards adult daphnids at the time when the new generation takes over, this seems to represent the worst case for the Daphnia population. Consequently, the timing between bottom-up effects and the feeding pressure of juvenile fish determines the extent of the decline. - (This manuscript is also available - in the form of a book - from Shaker Verlag GmbH, Postfach 101818, 52018 Aachen, Germany world-wide web address: http://www.shaker.de, electronic-mail address: info@shaker.de. It has been posted on the web sites of Dresden University of Technology with the permission of the publisher)
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40

Boyette, Adam Howell. "Parental investment and men's sexual behavior : life history theory and reproductive strategies in a sample of American men." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/a_boyette_121106.pdf.

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41

Lagrue, Clement, and n/a. "Alternative life-history strategies in the trematode Coitocaecum parvum (Opecoelidae) : effects of environmental factors and within-host competition." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080905.111744.

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From simple beginnings, when only one host was required, numerous parasitic organisms have evolved complex life-cycles involving two or more host species. For example, trematode parasites reproduce in vertebrates, their definitive host, but their current life cycle also typically involves two intermediate hosts that were added during the course of evolution. Vertebrates are often considered to be the ancestral hosts of trematodes although other scenarios exist. While multi-host life cycles are observed in distantly related groups of parasites, their evolution remains largely unexplored. In trematodes, while recent phylogenetic studies have shed light on the sequence along which the different hosts were incorporated in the cycle, conditions that favoured the evolution of such complex life cycles can only be hypothesized. However, one opportunity to understand the force shaping the evolution of complex life cycles is provided by the few trematode species in which the classical three-host cycle facultatively reverts to a shorter cycle (i.e. life cycle abbreviation). In this study, the effects of different environmental factors on the life history strategy of the trematode Coitocaecum parvum were investigated using laboratory and field studies. C. parvum is able to abbreviate its life cycle from three to two hosts by maturing early (i.e. progenesis) and producing eggs inside the second intermediate host; both life history strategies occur simultaneously in C. parvum populations. Environmental factors such as predator densities should strongly influence parasite life history strategies. In fact, this study shows that laboratory reared Coitocaecum parvum adopt preferentially the normal three-host cycle when chemical cues from the definitive host are added to their environment, while the shorter cycle is favoured when these cues are absent. However, in nature, multiple environmental factors are likely to be perceived by parasites. Consequently, C. parvum�s ability to adapt its developmental strategy to definitive host densities may be confounded by the complex combination of various environmental parameters. Within-host competition between parasites sharing a common host is also likely to influence individual life history strategies. Parasites could then use alternative life strategies to adaptively respond to intraspecific and interspecific competition. Indeed, this study found that C. parvum preferentially adopts the abbreviated cycle in the presence of competitors. However, in interspecific competition, C. parvum�s strategy also depends upon the competitor species, possibly influenced by the other species� transmission route. Furthermore, intensity of intraspecific competition proved to constrain C. parvum�s ability to use the abbreviated life cycle. Finally, genetic relatedness between co-infecting C. parvum individuals seems to affect parasite life strategy through kin selection: closely related individuals are more likely to adopt the same developmental strategy, when they share a host, than unrelated ones. C. parvum individuals adopting the abbreviated cycle are enclosed within a cyst in their intermediate host and must produce eggs by self-fertilization, the most severe case of inbreeding. It was hypothesized that their offspring would have reduced fitness due to inbreeding depression, therefore selecting against the shorter cycle. However, this study found no difference in the survival and infection success of offspring produced through the abbreviated and normal cycles. Furthermore, no evidence for a genetic basis of life cycle abbreviation was detected: the same proportion of offspring from both reproductive strategies adopted the shorter life cycle. The work in this thesis provides evidence that although life cycle abbreviation provides Coitocaecum parvum with a viable alternative life strategy, numerous factors promote or restrict the adoption of this strategy. While this life history strategy has no detectable effect on parasite fitness, both environmental parameters and within-host competition affect C. parvum life-history strategies, alternatively selecting for either the shorter or normal life cycle. Overall, the complexity of the parasite environment could maintain both developmental strategies in C. parvum populations and, on a broader scale, could have influenced the evolution of complex life cycles in parasites.
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42

Hotchkiss, Sarah L. "Life history strategies of three species of Cystophora (Phaeophyta, Fucales) from a shallow subtidal community in South Australia /." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phh832.pdf.

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43

Beesley, Leah. "Environmental stability : its role in structuring fish communities and life history strategies in the Fortescue River, Western Australia /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0129.

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44

Hülsmann, Stephan. "Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation." Doctoral thesis, Technische Universität Dresden, 2000. https://tud.qucosa.de/id/qucosa%3A24248.

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The population dynamics and demography of Daphnia galeata was analysed in a five year study in the biomanipulated Bautzen Reservoir. Samples were taken two times a week during the period May-July in the pelagic zone of this highly eutrophic water. Major bottom-up and top-down factors were determined during the study period and analysed with regard to their influence on Daphnia dynamics and life history. Field data on fecundity and population structure of D. galeata were combined with results from life table and growth experiments performed under approximately in situ conditions to gain insight into the mechanisms leading to a midsummer decline of this cladoceran species which dominates the zooplankton community in Bautzen Reservoir. Two main patterns of Daphnia dynamics emerged: In years without a midsummer decline the population increased slowly in spring, starting from low densities. High water transparency was observed already during the build-up of the population of D. galeata. Despite considerable fluctuations, Daphnia abundance remained on a high level throughout summer. In years with a midsummer decline the population started from relatively high densities in early May and more than doubled during one week. Peak densities were reached before the clear-water stage emerged. At the end of this period the population declined to low values which lasted for the rest of the summer. Fecundity of the Population of D. galeata declined, whereas the mean egg volume increased at the beginning of the clear-water stage as a result of declining food levels. The size at maturity (SAM) remained high during this period. Additionally, juvenile growth was reduced and the age at maturity was retarded. Survival probability was low for those daphnids born shortly before or during the clear-water stage compared to those born later. It can be concluded from these results that recruitment to adult stages is strongly reduced during the clear-water stage. The end of this period is marked by an alternation in generations. Only at that time can SAM be reduced because the new generation of adults matures at a smaller size, carrying small eggs. A high impact of non-predatory adult mortality can be expected when the population is dominated by a strong peak-cohort during the clear-water stage according to recruitment patterns during the build-up of the population. The most drastic decline both of Daphnia abundance and SAM was observed in those years when the biomass of juvenile fish exceeded 20 kg ha-1 at the end of the clear-water stage. Due to gape-size limitation juvenile fish mainly feed on juvenile daphnids during this period and thus, they reinforce bottom-up effects on the Daphnia population. When fish change their size selection towards adult daphnids at the time when the new generation takes over, this seems to represent the worst case for the Daphnia population. Consequently, the timing between bottom-up effects and the feeding pressure of juvenile fish determines the extent of the decline. - (This manuscript is also available - in the form of a book - from Shaker Verlag GmbH, Postfach 101818, 52018 Aachen, Germany world-wide web address: http://www.shaker.de, electronic-mail address: info@shaker.de. It has been posted on the web sites of Dresden University of Technology with the permission of the publisher)
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45

Janse, van Rensburg Susan. "Ecological significance of variation in Themeda triandra Forsk : a case of intra-specific divergence in life history strategies?" Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/6275.

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Includes bibliographical references (leaves 132-143).
Rangelands are a important resource for commercial, subsistence and game enterprises. However, their variabiligy poses a challenge for their effective management. This thesis was motivated by the need to contribute to a functional classification system for rangelands to guide managers in a way that adequately, yet simply, addresses ecological variation in South African rangelands. The approach was to investigate life history characteristics of rangelands at four sites representing climate extremes. These differed in the amount, and predictability, of rainfall and the incidence of frost. The approach was novel in that a single species, Themeda triandra, was used in an attempt to test predictions on sets of key traits associated with the different rainfall regimes. The underlying hypothesis was that density-dependent processes would be most important in mesic grasslands, requiring frequent defoliation by fire or grazing to maintain a productive Themeda sward. Climate variabiligy would be the most important determinant of grass growth in semi-arid grasslands. Vegetive and reproductive traits of Themeda would be expected to have diverged in response to these different selection pressures in the different populations. Observations were made on reproductive and vegetative traits in field populations in the four study areas and on plants grown from clonal material and seeds in a glasshouse to determine key axes of variation. Population responses to varying light and moisture levels were compared in a glasshouse experiment simulating the effects of different moisture regimes and competitive environments of source populations. Fecundity, seedbank characteristics, seedling numbers and population size structure were compared in field and glasshouse experiments. Production characteristics were compared in a clipping experiment conducted in the field. Results showed that different populations of Themeda exhibit divergent life history characteristics associated with different rainfall and temperature regimes. These differences are evident in the morphology, allocation patterns, leaf traits, germination biology and phenology of populations. The ecological significance and implications of trait divergence were clearly evident in demographic characteristics of the populations, in experimental responses to watering and shading, and in divergent growth responses to clipping experiments. The results were consistent with classic life history theory. In low, unpredictable rainfall regions, populations have evolved r-selected strategies whereas populations from high and predictable rainfall are characterized by K-selected traits. However the incidence of frost is also a factor influencing growth form divergence.
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46

Mell, Hugo. "Fast-slow strategies in human populations : applying insights from life history theory to explain patterns of interindividual variation." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE074.

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Des gradients sociaux ont été documentés pour une variété de comportements individuels. Au sein des pays occidentaux par exemple, les personnes ayant un statut socio-économique plus bas ont tendance à investir moins dans leur éducation, à fumer davantage, sont plus susceptibles de souffrir d'obésité et plus enclines à prendre des risques dans des contextes économiques. Ainsi, être exposé à des conditions de vie précaire semble engendrer une série de comportements, covariant de manière systématique. Ce syndrome comportemental a été principalement interprété comme le produit de déficits cognitifs ayant traits à la prise de décision et/ou à un manque de volonté. Dans ce manuscrit, nous explorons une approche différente, qui s'ancre dans les explications adaptationnistes des comportements humains. Au lieu d'appréhender les comportements observés chez les individus en situation de précarité comme des anomalies, ceux-ci sont perçus comme des ajustements des stratégies individuelles d'histoire de vie, adaptés à la vie dans des environnements précaires. En effet, nous approfondirons l'hypothèse selon laquelle un environnement précaire sélectionne des stratégies qui accordent davantage de poids aux bénéfices immédiats plutôt qu’aux investissements de long terme, affectant dès lors toute une gamme de comportements. Dans un premier temps, nous analyserons par le biais de modèles d'équations structurelles, différents jeux de données afin de mesurer le degré de covariation de comportements ayant trait à la reproduction, à l'investissement dans la santé et au niveau de confiance, ainsi que leur association éventuelle avec le niveau de précarité éprouvé pendant l'enfance ou à l'âge adulte. Globalement, nos résultats indiquent qu'une réduction de l’investissement dans la santé co-varie avec une stratégie de reproduction plus court-termiste, ainsi qu'un plus faible niveau de confiance. De plus, ce pattern est surreprésenté chez les personnes en situation de précarité, avec des effets persistants des conditions pendant l'enfance. En parallèle de ces travaux empiriques, nous nous sommes par ailleurs intéressés aux fondements théoriques de nos hypothèses de travail. Précisément, nous avons développé un modèle formel de stratégie d'histoire de vie prédisant les changements de préférences temporelles intra- et interindividuelles. Celui-ci nous a permis de mettre en évidence l’importance de deux facteurs distincts pour déterminer le degré optimal avec lequel des individus doivent préférer les récompenses de court-terme : 1) le niveau d'incertitude sur la probabilité de collecter une récompense délayée dans le temps, et 2) le coût d'opportunité à ne pas bénéficier de la récompense pendant la période de délai. Enfin, nous concluons ce travail en discutant des perspectives particulièrement intéressantes offertes par une intégration plus poussée de l'approche développée dans cette thèse, avec d'autres sciences sociales et sciences du comportement plus traditionnelles
Social gradients in behavior have been documented across various domains of people’s lives. In western countries, low SES individuals tend for instance to invest less in their education, to smoke more, are more subject to overweight and are more willing to take risks in financial settings. Being exposed to deprivation therefore seems to elicit a constellation of behaviors that appear to covary in a systematic fashion. This behavioral constellation of deprivation has been mostly interpreted as the product of poor decision making abilities, of a general failure of willpower. In this dissertation we explore a different interpretation that is rooted in adaptive explanations of human behavior. Instead of viewing the behaviors of low SES individuals as suboptimal deviations from a global optimum, they are seen as adjustments of people’s overall life strategies that are, from an evolutionary point of view, adaptive in the particular context of a deprived ecology. Indeed, we will explore the idea that deprived environments select for strategies that put more weight on present outcomes over uncertain future outcomes, and that this present orientation in low SES individuals propagates across a range of decision domains, giving rise to the constellation. To this aim, we first use structural equation models on observational data from a diversity of samples, to analyze the covariation between peoples’ behaviors in several relevant domains (health, reproduction, social trust) and their exposure to deprivation during childhood and/or adulthood. Overall, we find that a lower somatic effort tends to covary with a more short-term reproductive strategy, as well as lower social trust. This pattern is associated with a higher exposure to deprivation, with unique effects of early life conditions. In addition to this empirical work, we further investigate the theoretical underpinnings of our working hypotheses, from an adaptationist perspective. Specifically, we build a formal life history model to predict optimal changes in discounting within and between individuals. This allows us to highlight that the extent to which individuals prefer short-term rewards, should vary depending on two main parameters: 1) the uncertainty around their ability to actually collect delayed rewards, and 2) the opportunity costs of not having the reward during the delay. Finally, we conclude by discussing the promising perspective of further integrating the approach adopted in the present thesis, with more traditional social and behavioural sciences
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47

Miller, David Charles Moorcroft. "An individual-based modelling approach to examine life history strategies of sardine Sardinops sagax in the southern Benguela ecosystem." Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/8917.

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Includes bibliographical references (p. 177-194)
Hypotheses regarding the spawning strategy and recruitment of sardine (Sardinops sagax) in the southern Benguela ecosystem are tested using an individual-based Lagrangian particle tracking model linked with a 3-D hydrodynamic model of the region. Experiments focus on the dispersion of eggs and larvae among possible spawning and nursery areas. The two main areas of interest were the west coast upwelling region and the south coast shelf region (Agulhas Bank). A stage-based temperature-dependent development model is incorporated and vertical positioning schemes are tested. The spatial distribution and size structure of the sardine spawning stock for the period 1991-1999 are presented and a simple size-based fecundity model, combined with modelled recruitment, is used to determine the relative importance of each spawning and nursery area. The area of spawning plays a fundamental role in determining the destination of spawned eggs, and recruitment of sardine in the southern Benguela ecosystem appears to be divided into three recruitment systems by the circulation of the region: eggs spawned west of Cape Agulhas recruiting on the west coast (the WAB/WC-WC system), eggs spawned east of Cape Agulhas recruiting on the west coast (the CAB-WC system), and eggs spawned east of Cape Agulhas recruiting to the south coast (the SC-SC system). There is a slight increase in retention in the two nursery areas during winter, but the transport of eggs and larvae from the Agulhas Bank to the west coast is optimal during spring to early summer. Slow development arising from cold temperatures on the west coast could negatively impact recruitment by increasing offshore loss of individuals before they develop to a stage when they are able to actively avoid offshore currents and through its effect on mortality rate. This could explain the spatial separation of spawning and nursery areas in this system. The vertical position of individuals has an effect on the level of modelled recruitment and mortality rate, but observed vertical distributions of sardine egg and larvae do not significantly increase the level of modelled recruitment to optimal nursery areas. This suggests that efficient transport and retention are traded-off against other factors such as predator avoidance or prey abundance. Observed size structure and spatial distribution of the sardine spawning stock for 1991-1999 fluctuated greatly with most spawning centred on the western Agulhas Bank. When spawning was centred east of Cape Agulhas, recruitment was poor. No significant relationship could be established between potential reproductive output reaching the west coast and estimated recruitment, but positive recruitment anomalies required good transport to, and retention on, the west coast. A conceptual model of the early life history of sardine is proposed in light of limitations imposed by transport and retention of individuals. Lower primary production and the possibility of higher predation on the Agulhas Bank suggest that the south coast supports less recruitment than the west coast. The hypotheses tested using available data and model results could improve the understanding of recruitment of sardine in this complex ecosystem. These need to be validated by field observations. Additionally, further avenues for research that could help in developing a better understanding of the sardine life history in the southern Benguela ecosystem are suggested.
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48

Linhares, Jussiara Candeira SpÃndola. "Reproductive strategies of the crab Ucides cordatus (Crustacea, Brachyura; Ucididae)." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6143.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A reproduÃÃo à um dos principais eventos na vida de um indivÃduo, sendo relatados para Brachyura diferentes estratÃgias de reproduÃÃo. Este trabalho tem como objetivo descrever estratÃgias reprodutivas do caranguejo-uÃÃ, Ucides cordatus, no manguezal do Rio IgaraÃà â PI, observando a relaÃÃo das fases do ciclo reprodutivo com fatores ambientais. As coletas foram realizadas durante o perÃodo de 24 meses, nos quais os valores mensais de temperatura e pluviosidade foram registrados. ExcursÃes ao manguezal para a observaÃÃo do comportamento dos caranguejos foram realizadas no perÃodo de reproduÃÃo da espÃcie, denominado âandadaâ. Os ovÃrios e vasos deferentes dos animais foram analisados e classificados quanto ao estÃgio de maturaÃÃo. Os ovos de fÃmeas ovÃgeras foram contados para estimar a fecundidade. Um total de 720 indivÃduos foram analisados. Com base na anÃlise microscÃpica das gÃnadas foi observado que o perÃodo reprodutivo da espÃcie à sazonal e està inserido na estaÃÃo chuvosa. Este perÃodo à determinado por fÃmeas jà que machos estÃo aptos à reproduÃÃo todo o ano. Baseado na anÃlise gonadal, foi observado que o tamanho da largura da carapaÃa no qual 50% das fÃmeas e machos estÃo maturos foi 35,13 mm e 32,71 mm, respectivamente. Para maturaÃÃo morfolÃgica estes valores foram para fÃmeas 46 mm com base no crescimento da largura do abdÃmen e para machos 39,9 e 36,4 mm com base no crescimento dos quelÃpodos e comprimento do gonopÃdio respectivamente. Estes valores sÃo inferiores aos observados para outras regiÃes. A fecundidade observada para populaÃÃo tambÃm se mostrou inferior a de outra regiÃo, quando comparadas Ãs equaÃÃes de fecundidade. Foi verificado que o acasalamento da espÃcie ocorre durante a intermuda. Durante os fenÃmenos de âandadaâ o comportamento visualizado com maior intensidade foi a liberaÃÃo de ovos para o abdÃmen da fÃmea. Um pequeno nÃmero de cÃpulas foi observado, assim como disputas entre machos. Todos estes comportamentos ocorreram durante o perÃodo noturno, o que indica que para esta populaÃÃo o fenÃmeno da âandadaâ ocorre com maior intensidade à noite. Com base nos resultados, foi sugerida a hipÃtese que a alta intensidade de pesca do crustÃceo na regiÃo pode ter desencadeado as mudanÃas observadas na estratÃgia reprodutiva da populaÃÃo quando comparada a de outras regiÃes
The reproduction is one of the main events in an individual's life, being reported for Brachyura different reproduction strategies. This project has aimed to describe reproductive strategies of the caranguejo-uÃÃ, Ucides cordatus, in mangrove of IgaraÃÃ river - PI, observing the relationship of the reproductive cycle phases with environmental factors. The samples were obtained during one period of 24 months. During this period the values of temperature and pluviosity were monthly registered. Excursion to the mangroves for crabs behavior observation were accomplished in the mating period of, called âandadaâ. The ovaries and vas deferens of the animals were analyzed and classified regarding the maturation stage. The eggs of ovigerous females were counted to esteem the fecundity. A total of 720 individuals were analyzed. Based on gonad microscopic analysis it was observed that the reproductive period of the species is seasonal and occurs during at the rainy season. This period is determined by females since males are capable to the reproduction throughout year. Based in the gonadal analysis, it was observed the size of the carapace width where 50% of the females and males were mature, was 35.13 mm and 32.71 mm, respectively. For morphologic maturation these values were 46 mm to females with base in the growth of the width of the abdomen and 39.9 and 36.4 mm for males with base in the growth of the length of the chelipeds and length of the gonopod. These values are smaller when compared to the observed for other areas. The fecundity observed for the population studied was also inferior to the one of another area, when compared the fecundity equations. It was verified that the mating of the species occurs during the intermoult. During the "andada" phenomena, the behavior visualized with larger intensity was the liberation of eggs for the abdomen of the female. A small number of mating were observed, as well as fights among males. All these behaviors occurred during the night period, indicating that, for this population, the phenomenon of the "andada" occur with larger intensity at night. Based on results, it was suggested the hypothesis that the high intensity of fishing of the crustacean in the area might have unchained the changes observed in the reproductive strategy of the population when compared the one of other areas.
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49

Wilson, Scott Darren. "Influence of environmental variation on habitat selection, life history strategies and population dynamics of sympatric ptarmigan in the southern Yukon Territory." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1225.

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Climatic variation is an important driver of avian life history and population dynamics. Climate change models predict increased variability for many regions and to predict the effects on species, we need to examine how their life history characteristics influence their response to climate. I studied how environmental conditions influenced the ecology of white-tailed (Lagopus leucura) and rock ptarmigan (L. mutus) in tundra habitats of the southern Yukon Territory. Although sympatric in the study area, breeding territories were generally segregated, with white-tailed ptarmigan selecting steep, rocky slopes at higher elevations and rock ptarmigan preferring lower elevation sedge meadows. For both species, cold spring temperatures delayed the onset of breeding, resulting in smaller clutch sizes and fewer hatched young per female. However, delayed breeding led to a stronger reduction in these rates for rock ptarmigan, suggesting a lower resilience to extend reproductive effort in colder years. White-tailed ptarmigan were also more likely to re-nest following failure and had higher daily nest survival, both of which contributed to greater annual productivity compared to rock ptarmigan. Annual adult survival showed the opposite pattern to productivity as rock ptarmigan survival was 24 percent higher than white-tailed ptarmigan. This finding suggested a reproduction-survival trade-off exists for the two species, which may be driven by differing susceptibility to environmental factors in the region. Life history theory predicts that if the likelihood of future breeding opportunities is low, individuals should increase current reproductive effort, which may explain why white-tailed ptarmigan have longer breeding seasons and higher reproductive effort under unfavourable climatic conditions. Population models showed that growth rates (λ)were approximately stable for rock ptarmigan (λ=1.01), but declining for white-tailed ptarmigan (λ=0.96). Simulations showed that warmer spring temperatures over the next few decades would elevate λ by ~0.05 for both species, but the extent of increase in λ may be reduced with more variable spring conditions. Population growth will also depend on how changing winter conditions influence survival for each species. Model simulations suggest that if juvenile and adult survival are positively correlated, rock ptarmigan would be more resilient to severe years that simultaneously depress reproduction and survival.
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50

Clay, Thomas Anthony. "Drivers of variation in the migration and foraging strategies of pelagic seabirds." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267809.

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The ability to move and forage efficiently plays a major role in determining the fate of individuals, and has important implications for population dynamics and ecosystem functioning. Migration is a particular type of movement strategy, whereby animals may travel remarkable distances in order to take advantage of seasonality in resource availability or to avoid arduous winter conditions; however, this can be at a cost in terms of increased mortality. Indeed, anthropogenic threats in non-breeding areas are a major cause of population declines and a better understanding of non-breeding spatial ecology is required in order to advance both ecological theory and conservation management. The recent development of animal tracking technologies, in particular light-based geolocation, has made it possible to track large-scale and long-term movements; however, there are still gaps in our knowledge, such as the links between migratory and reproductive performance, connectivity among populations and the ontogeny of migration strategies. In this thesis, I utilise multi-species and longitudinal datasets from albatrosses and petrels, some of the most mobile species on Earth, to explore the drivers of variation in movements, habitat use and foraging behaviour, and the implications for life history and conservation. In Chapter 1, I provide an overview of the key topics of this thesis. In Chapter 2, I provide quantitative recommendations of minimum sample sizes needed to track pelagic seabird migrations, using data from 10 species. In Chapter 3, I examine between- and within-population differences in the habitat preferences and distributions of albatrosses, including the relative roles of habitat specialization and intra-specific competition. In Chapter 4, I investigate the year-round movement and foraging strategies of petrels living in nutrient-poor environments. In Chapter 5, I examine potential links between foraging behaviour during the non-breeding season and reproductive senescence. In Chapter 6, I explore the ontogeny of foraging behaviour and foraging site fidelity in young albatrosses, shedding light on their “lost years” at sea. Finally, I conclude with a general discussion summarizing main findings and suggesting future work. Overall, my results highlight the complex relationships among individual traits, the environment, movements and foraging behaviour, and population dynamics across the lifespan of individuals, with implications for the conservation of this highly threatened group of species.
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