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Paternal care, filial cannibalism and sexual conflict in the sand goby, Pomatoschistus minutusLissåker, Maria January 2006 (has links)
Natural and sexual selection and sexual conflict are forces shaping the evolution of reproductive behaviour, while constrained by factors like environment, physiology and life-history trade-offs. Parental care is costly both in terms of time and energy. In fish, filial cannibalism is a strategy for caring males to compensate for some of the energy loss. Human impact like eutrophication also alters the basics for animals living in that environment. It is fundamental to any species to adjust its behaviour to a changing environment. Studying sand goby males, I found trade-offs both regarding parental care allocations, like ventilation vs. predator defence, and investment in present vs. future reproductive success. Paternal sand gobies exposed to water with low oxygen levels increased their fanning effort but did not compensate by eating more eggs, even though an increased current parental effort should affect future reproductive success negatively. Investigating if patterns of filial cannibalism change with time of season, I found no correlation. Theory predicts that it should pay more to eat eggs early, when future mating potential is higher than late in the season. However, as early hatching fry are likely to gain higher fitness through larger size the next breeding season, this may provide an opposing selection pressure. In species with male care the only way a female can affect the level of post-spawning care is by choosing a good mate. A female preference to spawn in nests that already contain eggs of other females has been interpreted as a means to avoid filial cannibalism through a dilution effect or to decrease the costs of search time. Yet, in my study females did not avoid filial cannibalism by preferring large clutches to small ones. Oxygenation of the eggs might be a key factor, since both large and small females preferred spawning in nests with small clutches. Thus, as in most animals, trade-offs clearly govern the reproductive behaviour of sand gobies.
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Pre- and post-copulatory sexual selection in the fowl, Gallus gallusLøvlie, Hanne January 2007 (has links)
The evolutionary goal of individuals is reproduction and sexual selection favours traits improving reproductive success. When males invest less than females in offspring, males have potentially a higher reproductive rate than females. This typically results in sex-specific reproductive strategies of male-male competition and female choice of mating partner. Under polyandry, sexual selection can continue after copulation as sperm competition and cryptic female choice. This thesis focuses on male and female pre- and post-copulatory reproductive strategies in the promiscuous red junglefowl, Gallus gallus ssp., and its domestic subspecies the domestic fowl, Gallus gallus domesticus. Males impose high re-mating rates on females, which triggers female resistance in copulations. In addition, when sexual harassment increases, females re-mate at times of day when male mating propensity is lower, to avoid intense sexual harassment. Males allocate sperm supplies differentially according to (i) variation in female polyandry and own competitive ability, (ii) earlier sperm investment in a female, and (iii) female reproductive quality, signalled by female comb size. Males also perform ‘aspermic’ copulations (i.e. copulations with no semen transfer), which inhibit polyandry and in turn reduce sperm competition. In mating opportunities with relatives, males do not avoid inbreeding. However, females avoid inbreeding before copulation through kin recognition and after copulation by selecting against related males’ sperm. These results show that selection on males to re-mate at higher rates than females and copulate indiscriminately according to partner relatedness, trigger counteracting female responses, creating the potential for sexual conflict over fertilisation. Teasing apart pre- and post-copulatory strategies and the contribution of each sex therefore becomes crucial in order to understand the evolution of reproductive strategies and the mechanisms affecting paternity.
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Evolutionary quantitative genetics and genomics applied to the study of sexually dimorphic traits in wild bighorn sheep (Ovis canadensis)Poissant, Jocelyn Unknown Date
No description available.
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Evolutionary quantitative genetics and genomics applied to the study of sexually dimorphic traits in wild bighorn sheep (Ovis canadensis)Poissant, Jocelyn 06 1900 (has links)
The independent evolution of the sexes may often be constrained if male and female homologous traits share a similar genetic architecture. Thus, cross-sex genetic covariance is assumed to play a key role in the evolution of sexual dimorphism (SD) with consequent impacts on sexual selection, population dynamics and the speciation process. I used quantitative genetics tools to assess the importance of sex-specific genetic variance in facilitating the evolution of body mass and horn size SD in wild bighorn sheep from Ram Mountain, Alberta. I also developed a bighorn sheep genetic linkage map composed of 247 microsatellite markers to gain insights about the genetic architecture of trait variation. Finally, I conducted systematic reviews and meta-analyses of published cross-sex genetic correlations (rMF, a standardized estimate of cross-sex genetic covariance) to test basic hypotheses about the importance of sex-specific genetic variance in the evolution of SD and mechanisms responsible for generating such variance. My results demonstrated that sex-specific genetic variance was present in bighorn sheep and that it likely played an important role in alleviating intralocus sexual conflicts. The quantitative trait locus (QTL) mapping analysis resulted in the identification of numerous loci influencing body mass and horn dimensions, some of which had apparent sex-specific effects. An analysis of 553 rMF estimates recovered from 114 published sources allowed demonstrating that 1) the evolution of SD was generally constrained by positive cross-sex genetic covariance, 2) levels of SD were often sub-optimal, and 3) sex-specific genetic variance was an important mechanism allowing the evolution of SD. In addition, I confirmed the long-standing hypothesis of a general decline in rMF with age. Sexual dimorphism is an important evolutionary phenomenon, but our understanding of its evolution is still limited. After decades of speculation, my research has provided clear empirical evidence for the importance of sex-specific genetic variance in allowing its evolution. / Ecology
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Determinants of genomic diversity in the collared flycatcher (Ficedula albicollis)Dutoit, Ludovic January 2017 (has links)
Individuals vary from each other in their genetic content. Genetic diversity is at the core of the evolutionary theory. Rooted in a solid theoretical framework developed as early as the 1930s, current empirical observations of genomic diversity became possible due to technological advances. These measurements, originally based on a few gene sequences from several individuals, are becoming possible at the genome scale for entire populations. We can now explore how evolutionary forces shape diversity levels along different parts of the genome. In this thesis, I focus on the variation in levels of diversity within genomes using avian systems and in particular that of the collared flycatcher (Ficedula albicollis). First, I describe the variation in genetic diversity along the genome of the collared flycatcher and compare it to the amount of variation in diversity across individuals within the population. I provide guidelines on how a small number of makers can capture the extent of variability in a population. Second, I investigate the stability of the local levels of diversity in the genome across evolutionary time scales by comparing collared flycatcher to the hooded crow (Corvus (corone) corone). Third, I study how selection can maintain variation through pervasive evolutionary conflict between sexes. Lastly, I explore how shifts in genome-wide variant frequencies across few generations can be utilised to estimate the effective size of population.
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Developmental mechanisms of adaptive phenotypes and associated ecological relevance in the semiaquatic bugs / Mécanismes développementaux des phénotypes adaptatifs et leur importance écologique chez les insectes semi-aquatiquesCrumière, Antonin 14 December 2017 (has links)
Comprendre comment est générée la diversité biologique est un enjeu majeur de la biologie évolutive. Chaque espèce vit dans un environnement écologique qui lui est propre et dans lequel elle s’est adaptée au cours de l’évolution par les moyens de la sélection naturelle. Chaque espèce est également soumise à la sélection sexuelle contribuant au dimorphisme entre les sexes. Les traits phénotypiques associés au succès évolutif sont formés lors du développement par l’action de gènes qui sont transmis de génération en génération. Ces traits et ces gènes varient d’une espèce à une autre et contribuent directement à la diversité morphologique. La compréhension des interactions entre les mécanismes développementaux et les pressions écologiques permettent de mieux comprendre les processus qui influent sur la diversité morphologique et l’évolution des espèces. Obtenir une vision intégrative est un réel défi et demande de combiner diverses approches. Au cours de ma thèse, j’ai utilisé les insectes semi-aquatiques (Gerromorphes) qui sont un modèle permettant de lier évolution, écologie et développement. En utilisant différentes approches j’ai pu mettre en évidence des gènes impliqués dans le développement de divers traits adaptatifs, l’importance de ces traits dans un contexte écologique et leur impact sur l’évolution du groupe des Gerromorphes. L’ensemble des résultats obtenus améliore notre compréhension de comment sélection naturelle et sélection sexuelle, en agissant sur les mécanismes génétiques, génèrent de la diversité morphologique. / Understand how biodiversity is generated is a major goal in evolutionary biology. Every species live in a specific ecological habitat where they adapted during evolution by the mean of natural selection. Every species is also under sexual selection that generates dimorphism between the sexes. Adaptive traits contributing to evolutionary success are shaped during development by the action of genes that are transmitted through generations. These traits and genes vary across species and directly contribute to generate morphological diversity. The study of the interactions between developmental genetic mechanisms and selective ecological pressures allow a better understanding of the processes generating morphological diversity and driving the evolution of species. Obtain an integrative view is a challenge and required the combination of different approaches. During my PhD, I used the semiaquatic bugs (Gerromorpha) that are model systems allowing to link evolution, ecology and development. By using various approaches I could highlight genes involved in the development of different adaptive traits, the relevance of these traits in an ecological context and their impact on the evolution of the group of Gerromorpha. Altogether these results improve our understanding of how natural and sexual selection, by acting on genetic mechanisms, generate morphological diversity.
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Experimental Studies of the Divergence of Pre- and Postcopulatory Phenotypes in Male DrosophilaKwok, Kevin 13 May 2021 (has links)
ABSTRACT
A major focus in biology is understanding the diversification of life and the processes that cause it. Much of this diversity is in the form of phenotypic variation among populations and species. In this thesis, I investigate two separate aspects of such phenotypic divergence. The first is the divergence of male mate preferences and their potential contribution to precopulatory sexual isolation and speciation. The second is the divergence of postcopulatory phenotypic divergence in the form of seminal fluid protein expression.
With respect to the first aspect, in two separate experiments I investigated the contribution of male mate preferences to sexual isolation between two closely related fruit fly species experiencing differential costs to hybridization, Drosophila recens and Drosophila subquinaria. Male mate preferences are of particular interest because of their potential contribution to sexual isolation, a form of reproductive isolation which can contribute to speciation in sexually reproducing species. In the first experiment, I test for the presence of male mate preferences in each of the two species and whether the relative strength of the preference is concordant with the cost of hybridization. I found that that D. subquinaria males indiscriminately courted both their own (i.e. homospecific) females and heterospecific D. recens females. While D. recens from allopatry showed a similar pattern, those from sympatry courted their own females more than heterospecific females, indicating a pattern of reproductive character displacement. In the second experiment I test the role of learning in the context of these male mate preference in D. recens, and whether learning also showed a pattern of reproductive characteristic. I did not find evidence of learning in that D. recens males did not reduce their courting intensity towards heterospecific females after experiencing rejection by similar females. Consequently, I did not find an indication of reproductive character displacement.
Finally, with respect to postcopulatory phenotypic divergence, I studied differences in seminal fluid protein expression between experimental populations of D. melanogaster experiencing one of three mating environments allowing for differing opportunities of mate competition and the environment in which it took place. These three mating environments include one in which mate competition was absent (MCabsent,), one in which mate competition occurred in a small, structurally simple environment (MCsimple), and one in which mate competition occurred in a larger, somewhat more complex environment (MCcomplex,). Male seminal fluids are of particular interest due to their ability to mediate postcopulatory competition between males and, therefore, can be used to manipulate females to a male’s own fitness benefit, potentially at her expense (i.e. sexual conflict). I investigated divergence in one particular seminal fluid protein implicated in sexual conflict, sex peptide (Acp70A). Whereas, gene expression levels among males from the three-mating treatment did not differ on average, relative stored quantities did, with MCcomplex males carrying significantly less sex peptide than either of MCabsent or MCsimple males (which did not differ from one another). This result suggests that mate competition and the environment in which it occurs play a significant role in the divergence of sex peptide phenotypes.
ABSTRAIT Un objectif majeur de la biologie est de comprendre la diversification de la vie et les processus qui la provoquent. Une grande partie de cette diversité se présente sous la forme de variations phénotypiques entre les populations et les espèces. Dans cette thèse, j'étudie deux aspects distincts d'une telle divergence phénotypique. Le premier est la divergence des préférences des mâles et leurs contributions potentielles à l'isolement sexuel pré-copulatoire et à la spéciation. Le second est la différence de la divergence phénotypique post-copulatoire sous la forme de l'expression des protéines du liquide séminal. En ce qui concerne le premier aspect, dans deux expériences distinctes, j'ai étudié la contribution des préférences de compagnon mâle à l'isolement sexuel entre deux espèces de mouches des fruits étroitement liées subissant des coûts différentiels d'hybridation, Drosophila recens et Drosophila subquinaria. Les préférences des mâles sont particulièrement intéressantes en raison de leurs contributions potentielles à l'isolement sexuel, une forme d'isolement reproductif qui peut contribuer à la spéciation des espèces se reproduisant sexuellement. Dans la première expérience, je teste la présence de préférences de compagnon mâle dans chacune des deux espèces et si la force relative de la préférence est concordante avec le coût de l'hybridation. J'ai constaté que les mâles de D. subquinaria courtisaient sans discernement à la fois leurs propres femelles (c'est-à-dire homospécifiques) et les femelles hétérospécifiques de D. recens. Alors que D. recens de l'allopatrie a montré un modèle similaire, ceux de la sympatrie courtisaient leurs propres femelles plus que les femelles hétérospécifiques, indiquant un modèle de déplacement du caractère reproducteur. Dans la deuxième expérience, je teste le rôle de l'apprentissage dans le contexte de ces préférences de compagnon masculin dans D. recens, et si l'apprentissage a également montré un modèle de caractéristique de reproduction. Je n'ai pas trouvé de preuve d'apprentissage dans la mesure où les mâles D. recens ne réduisaient pas leur intensité de fréquentation envers les femelles hétérospécifiques après avoir été rejetés par des femelles similaires. Par conséquent, je n'ai pas trouvé d'indication de déplacement du caractère reproducteur.
Enfin, en ce qui concerne la divergence phénotypique post-copulatoire, j'ai étudié les différences dans l'expression des protéines du liquide séminal entre les populations expérimentales de D. melanogaster connaissant l'un des trois environnements d'accouplement, permettant différentes possibilités de compétition de compagnon et l'environnement dans lequel elle a eu lieu. Ces trois environnements d'accouplement incluent un environnement dans lequel la compétition entre partenaires était absente (MCabsent,), un dans lequel la compétition entre partenaires se produisait dans un petit environnement structurellement simple (MCsimple) et un dans lequel la compétition entre partenaires se produisait dans un environnement plus grand et un peu plus complexe (MCcomplexe,). Les fluides séminaux mâles sont particulièrement intéressants en raison de leur capacité à négocier la compétition post-copulatoire entre les mâles et, par conséquent, peuvent être utilisés pour manipuler les femelles dans l'intérêt de la forme physique d'un mâle, potentiellement à ses dépens (c'est-à-dire conflit sexuel). J'ai étudié la divergence dans une protéine du liquide séminal particulière impliquée dans un conflit sexuel, le peptide sexuel (Acp70A). Alors que les niveaux d'expression génique chez les mâles du traitement à trois accouplements ne différaient pas en moyenne, les quantités relatives stockées le faisaient, les mâles MCcomplexe portant significativement moins de peptide sexuel que les mâles MCabsent ou MCsimple (qui ne différaient pas les uns des autres). Ce résultat suggère que la compétition de partenaire et l'environnement dans lequel elle se produit jouent un rôle important dans la divergence des phénotypes des peptides sexuels.
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Examining the Interplay Between Sexual Conflict, Social Networks, and Polyandry / SEXUAL CONFLICT, SOCIAL NETWORKS, AND POLYANDRYYan, Janice L. January 2024 (has links)
Sexual conflict occurs when the reproductive optima of males and females are at odds with one another. Conflict between the sexes is ubiquitous across the animal kingdom and is expected to influence the social dynamics of group-living animals. Yet, most social behaviour studies do not address the potential ramifications that sexual conflict can have on social interactions. For my thesis, I used bed bugs (Cimex lectularius) to bridge the gap between sexual conflict and social behaviour. In Chapter 1, I developed a novel semi-naturalistic arena for tracking bed bugs to uncover how sexual conflict shapes animal social networks. My results show that male and females can be in conflict over the social environment. In Chapter 2, I examined how female sexual history shapes mating interactions using bed bugs. First, I showed that realistically high rates of traumatic insemination relative to lower rates dramatically reduce female fitness. Next, I manipulated female insemination status in a realistic group setting and found that males can exhibit strong mate choice even in a mating system with seemingly little male reproductive investment. Lastly, I tracked avoidance behaviour exhibited by female bed bugs as they received successive inseminations and demonstrated that female bed bugs possess plastic avoidance strategies based on their mating history. In Chapter 3, I examined how social experience shapes sexual interactions in a complex, competitive environment and found that social experience did not improve male or female bed bugs’ sexual competence. Finally, in Chapter 4, I extended my work on polyandry to fruit flies (Drosophila melanogaster) and showed that realistically high rates of female multiple mating can increase female fitness. In each chapter, I discuss the significance of my findings as they relate to sexual selection and the evolution of social and sexual strategies and behaviours in both sexes. / Dissertation / Doctor of Philosophy (PhD) / Sexual conflict occurs when the reproductive interests of males and females are not in alignment with one another. A common form of sexual conflict occurs when males want to mate more often than females, resulting in harassment of females. Such conflict between the sexes over mating is common across the animal kingdom. While there are many evolutionary consequences of sexual conflict, little is known about how sexual conflict influences the social behaviours of animals. For my thesis, I used bed bugs (Cimex lectularius) to bridge the gap between sexual conflict and social behaviour. I showed that bed bugs are under intense sexual conflict over mating rates which influences both females’ social preferences and their behavioural responses to males. I also found that bed bug females often mate with multiple males, which plays a large role in male mating behaviours and strategies. Finally, using fruit flies (Drosophila melanogaster), I show that mating with multiple males can sometimes be highly beneficial to females. The results of my studies have important implications for understanding the evolution of social and sexual behaviours in both sexes.
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Habitat composition, sexual conflict and life history evolution in Coelopa frigidaEdward, Dominic Alexander January 2008 (has links)
This thesis describes an investigation into the effects of habitat composition, principally the composition of algae in a wrack bed, on the life history of the seaweed fly, Coelopa frigida. The mating system of C. frigida is dominated by intense sexual conflict characterised by frequent harassment by males leading to a vigorous pre-mating struggle. This response leads to sexual selection for large male size and sexual dimorphism. The mating behaviour of C. frigida is affected by their environment, with exposure to brown algae inducing harassment in males and oviposition in females. Despite more than two decades of research into coelopid reproduction little is known about how habitat composition alters the patterns and processes of sexual conflict. Studies contained in this thesis consider environmental influences that both directly and indirectly influence sexual conflict. Direct effects of the environment are measured by conducting mating trials following culture of C. frigida on different species of algae and by exposing males to different species of algae. This work is accompanied by studies of larval development and adult survival on different algae. In recent years it has been observed that the distribution of European coelopids has undergone a northward range shift. An investigation into the current distribution of European coelopid species and a discussion of the effects of climate change that may have caused this change is included. Finally, the use of stable isotope analysis to determine the diet of wild coelopids and alternative statistical methods to analyse mating trials are described.
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Polyandry and the evolution of reproductive divergence in insectsNilsson, Tina January 2004 (has links)
<p>Multiple mating by females is common in nature. Yet, the evolution and maintenance of polyandry remains a bit of an evolutionary puzzle. It was my aim in this thesis to reach a greater understanding of this phenomenon as well as to investigate the consequences of polyandry on the evolution of reproductive divergence in insects. In an extensive meta analysis addressing the direct effects of multiple mating on female fitness in insects, I found that insects gain from multiple matings in terms of increased lifetime offspring production. In species without nuptial feeding, increased mating rate leads to decreased female lifespan and my results strongly support the existence of an intermediate optimal female mating rate. However, results from an experimental study where I examined the relationship between female fitness and mating rate in the bean weevil (Callosobruchus maculatus) showed that female fitness was maximized at two alternative mating rates, indicating that some species may exhibit a more complex relationship between the costs and benefits of mating. In the meta analysis on species with nuptial feeding, I found only positive effects of increased mating rate and the puzzle is rather what constrains the actual mating rates of females in these groups.</p><p>Sexual selection is a very potent driver of rapid evolutionary change in reproductive characters. Most research has focussed on precopulatory sexual selection, but in promiscuous species sexual selection continues after copulation and variance in male fertilization success gives rise to postcopulatory sexual selection. In this thesis I found that three allopatric populations of the red flour beetle (Tribolium castaneum) have diverged in traits related to reproduction. Male genotype affected all aspects of female reproduction, but more interestingly, males and females interacted in their effect on offspring production and reproductive rate, showing that the divergence was due to the evolution of both male and female reproductive traits.</p><p>When studying postcopulatory sexual selection, sperm competition has been put forward as the main source of variance in fertilization success. The results from a set of double-mating experiments, using the same populations of flour beetles, provided strong evidence that cryptic female choice is also important in generating variance in male fertilization success. I found not only main effects of female genotype on male fertilization success but also male-female interactions which provide more unambiguous evidence for cryptic female choice. Finally, I attempted to uncover which male signals-female receptors are involved in the reproductive divergence observed in the Tribolium populations. In a double-mating experiment I manipulated female perception of two male reproductive signals, copulatory courtship and cuticular hydrocarbons, and the results indicate that, within populations, both signals are sexually selected. However, only male cuticular hydrocarbons seem to be involved in the reproductive divergence between the populations. </p><p>In conclusion, multiple mating by female insects can be understood solely in terms of direct fitness benefits resulting from increased offspring production. I have shown that postcopulatory sexual selection can lead to rapid divergence in reproductive traits related to mating and that cryptic female choice plays an important role in this divergence.</p>
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