In birds, song can evolve quickly through cultural transmission and due to errors in the learning process may result in regional dialects. A lack of dialectal recognition may be a critical component of reproductive isolation through female mate preference. I investigated the role of cultural divergence in reproductive isolation in a widespread Neotropical passerine the rufous-collared sparrow (Zonotrichia capensis). In Chapter II, I investigated, the role of female preference for and male territorial response towards, local and non-local dialects in two allopatric populations. Females in both populations preferred their local dialect to the dialect of an allopatric population only 25 km away. In contrast, males showed similar territorial response to all conspecific dialects. Premating reproductive isolation based on culture may exist among the study populations. In chapter III, I investigated if cultural divergence can drive population divergence by examining dialects and variable microsatellite loci among eight populations of Z. capensis. I investigated the presence of population divergence and then identified the mechanism that may be driving the pattern. Apart from culture, a geographic barrier (the Andean ridge), elevation, and geographic distance were potential mechanisms of population divergence that I considered. All sites exhibited localized dialects, except for two closest neighboring populations. Populations exhibited genetic differentiation with support for the presence of five genetic clusters. Culture does not appear to be driving population divergence because song dialects and genetic population structure were not correlated. Populations separated by an Andean ridge did not display higher genetic or song differences than distance would predict, suggesting that the ridge is not driving population divergence. Elevation was not correlated to song or genetic differentiation. Both song divergence and microsatellite allele frequency differentiation were correlated with geographic distance suggesting a pattern of isolation by distance. Overall, geographic distance is the best predictor of population divergence in this system. Cumulatively, I found that culture might promote assortative mating via female mate choice, perhaps generating partial reproductive isolation; however, song dialect differences among contiguous populations is not currently driving population divergence in this species. / Ph. D.

<p>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.</p>

As interações entre os membros de um grupo social possuem um importante efeito sobre os padrões de competição, cooperação e acasalamento dos indivíduos, interferindo, assim, na aptidão dos mesmos. Os indivíduos podem se relacionar de maneira preferencial, estabelecendo vínculos sociais. A manutenção destes vínculos pode aumentar longevidade e também o sucesso reprodutivo. Historicamente, houve uma tendência em se investigar a formação de associações intersexuais e, consequentemente a seleção de parceiros, através do ponto de vista do macho, restando à fêmea um papel passivo neste processo. O objetivo deste trabalho foi investigar a formação de associações intra e intersexuais em cobaias (Cavia porcellus) vivendo em colônia e verificar se em ambiente controlado, onde a interferência dos machos entre si e sobre as fêmeas era limitada, as fêmeas demonstram preferência por um macho específico, dando indícios de sua participação na formação das associações intersexuais. Para isto, a estrutura social das cobaias na colônia foi definida por meio do cálculo do índice de associação entre os indivíduos e de parâmetros de redes sociais (força e centralidade). Em seguida, a preferência das fêmeas foi testada em um cercado experimental com três compartimentos, no qual dois abrigavam machos restritos a seu ambiente pelo uso de coleira e guia, e um deles permanecia vazio. As fêmeas possuíam acesso livre a todos os compartimentos por duas horas. A análise da preferência das fêmeas se deu pela comparação do tempo que permaneceram em cada um dos compartimentos (Testes de Mann-Whitney e Kruskal-Wallis, nível de significância: 5%). As cobaias formaram associações preferenciais intra e intersexuais, sendo as associações entre as fêmeas mais fortes do que aquelas entre machos ou entre fêmeas e machos quando a colônia era composta por um número maior de indivíduos. Nas relações intersexuais, as fêmeas apresentaram relações mais fortes com dois dos machos em relação aos outros da colônia. Os resultados do teste de escolha refletiram as associações na colônia: não houve diferença estatística no tempo de permanência das fêmeas com os machos que possuem relações mais fortes com as fêmeas. Um dos machos não foi preferido em nenhum dos testes e de modo geral, as fêmeas passaram mais tempo no compartimento vazio do que acompanhadas dos machos. Os resultados encontrados sobre estrutura social, com a formação de associações preferenciais e teste de escolha indicam que as fêmeas apresentam preferência por machos específicos, dando indícios de sua participação na formação das associações intersexuais, e possivelmente, na seleção de parceiros. / Interactions among members of a social group have an important consequence in competition, cooperation and mating patterns, interfering in their fitness. Animals can associate preferentially and stablish social bonds. Bond maintenance can increase lifespan and reproductive success. Historically, there is a tendency in investigating male-female relationships and, consequently, mate selection, through male view, placing females in a passive position in this process. This research aimed to investigate the formation of intra and intersexual relationships in guinea pigs (Cavia porcellus) living in colony and verify if, in a controlled environment, where male interference were limited, females would prefer a specific male, indicating an active position in intersexual relationships. The guinea pig social structure was defined using the simple ratio association index and the social network analysis. Female preference was tested in a three partitions fenced , the central was empty and the laterals had a male restricted to it by guinea-pig collar. Females were free to move around all during 2 hours. Female preference analysis was made by comparisons between female time in each partition (Mann Whitney and Kruskal-Wallis, significance: 5%). Results showed that in colony females make intra and inter preferential associations, strongest among females-than among male-male or female-male in a higher number of individuals in the colony. In female-male associations, females had stronger relationship with two males from their colony. Results of preference tests reflect association preferences in colony: there were no difference in female time with the two prefered males of the colony. The third male was never chosen, and females prefered to spend more time in the empty partition. Results about social structure with association preferences, and in preference tests show the active role of females in intersexual associations and, possibly, in mate selection.

<p>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, <i>Gallus</i> <i>gallus ssp.</i>, and its domestic subspecies the domestic fowl, <i>Gallus gallus</i> <i>domesticus</i>. 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.</p>

<p>In the fifteen-spined stickleback, <i>Spinachia spinachia</i>, males provide females with direct benefits by fanning, cleaning and guarding the offspring. Males announce their parental skills through intense body shakes during courtship. Females preferred to mate with more intensely shaking males. As a result, females got better fathers for their offspring, as such males achieved a higher hatching success. Not only did male behavioural cues attract females, but males also used their nests as extrabodily ornaments. The nest is held together with shiny secretional threads consisting of a glycoprotein. Females chose to spawn in nests with more secretional threads. A likely reason for this is that the threads are metabolically costly for the male to produce and the amount of secretion indicates a male's nutritional status, which is of great importance as parental duties are energetically costly. Moreover, females preferred nests built high up in the vegetation, as such nests were safer from egg predators. Competition with other males for females favoured males building higher nests than did their neighbours, probably because females preferred high nests. Male-male interactions, such as sneaking and egg stealing, caused decreased paternity among males in nature as assessed by a microsatellite analysis. Males adjusted their paternal effort according to their previous investment in the brood, but not according to paternity. Thus, female choice is based on multiple cues and results in better paternal care. Males invest in courtship, male-male competition, nest construction and paternal care, the outcome determining their success in mate attraction.</p>

In the fifteen-spined stickleback, Spinachia spinachia, males provide females with direct benefits by fanning, cleaning and guarding the offspring. Males announce their parental skills through intense body shakes during courtship. Females preferred to mate with more intensely shaking males. As a result, females got better fathers for their offspring, as such males achieved a higher hatching success. Not only did male behavioural cues attract females, but males also used their nests as extrabodily ornaments. The nest is held together with shiny secretional threads consisting of a glycoprotein. Females chose to spawn in nests with more secretional threads. A likely reason for this is that the threads are metabolically costly for the male to produce and the amount of secretion indicates a male's nutritional status, which is of great importance as parental duties are energetically costly. Moreover, females preferred nests built high up in the vegetation, as such nests were safer from egg predators. Competition with other males for females favoured males building higher nests than did their neighbours, probably because females preferred high nests. Male-male interactions, such as sneaking and egg stealing, caused decreased paternity among males in nature as assessed by a microsatellite analysis. Males adjusted their paternal effort according to their previous investment in the brood, but not according to paternity. Thus, female choice is based on multiple cues and results in better paternal care. Males invest in courtship, male-male competition, nest construction and paternal care, the outcome determining their success in mate attraction.

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.

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.

As interações entre os membros de um grupo social possuem um importante efeito sobre os padrões de competição, cooperação e acasalamento dos indivíduos, interferindo, assim, na aptidão dos mesmos. Os indivíduos podem se relacionar de maneira preferencial, estabelecendo vínculos sociais. A manutenção destes vínculos pode aumentar longevidade e também o sucesso reprodutivo. Historicamente, houve uma tendência em se investigar a formação de associações intersexuais e, consequentemente a seleção de parceiros, através do ponto de vista do macho, restando à fêmea um papel passivo neste processo. O objetivo deste trabalho foi investigar a formação de associações intra e intersexuais em cobaias (Cavia porcellus) vivendo em colônia e verificar se em ambiente controlado, onde a interferência dos machos entre si e sobre as fêmeas era limitada, as fêmeas demonstram preferência por um macho específico, dando indícios de sua participação na formação das associações intersexuais. Para isto, a estrutura social das cobaias na colônia foi definida por meio do cálculo do índice de associação entre os indivíduos e de parâmetros de redes sociais (força e centralidade). Em seguida, a preferência das fêmeas foi testada em um cercado experimental com três compartimentos, no qual dois abrigavam machos restritos a seu ambiente pelo uso de coleira e guia, e um deles permanecia vazio. As fêmeas possuíam acesso livre a todos os compartimentos por duas horas. A análise da preferência das fêmeas se deu pela comparação do tempo que permaneceram em cada um dos compartimentos (Testes de Mann-Whitney e Kruskal-Wallis, nível de significância: 5%). As cobaias formaram associações preferenciais intra e intersexuais, sendo as associações entre as fêmeas mais fortes do que aquelas entre machos ou entre fêmeas e machos quando a colônia era composta por um número maior de indivíduos. Nas relações intersexuais, as fêmeas apresentaram relações mais fortes com dois dos machos em relação aos outros da colônia. Os resultados do teste de escolha refletiram as associações na colônia: não houve diferença estatística no tempo de permanência das fêmeas com os machos que possuem relações mais fortes com as fêmeas. Um dos machos não foi preferido em nenhum dos testes e de modo geral, as fêmeas passaram mais tempo no compartimento vazio do que acompanhadas dos machos. Os resultados encontrados sobre estrutura social, com a formação de associações preferenciais e teste de escolha indicam que as fêmeas apresentam preferência por machos específicos, dando indícios de sua participação na formação das associações intersexuais, e possivelmente, na seleção de parceiros. / Interactions among members of a social group have an important consequence in competition, cooperation and mating patterns, interfering in their fitness. Animals can associate preferentially and stablish social bonds. Bond maintenance can increase lifespan and reproductive success. Historically, there is a tendency in investigating male-female relationships and, consequently, mate selection, through male view, placing females in a passive position in this process. This research aimed to investigate the formation of intra and intersexual relationships in guinea pigs (Cavia porcellus) living in colony and verify if, in a controlled environment, where male interference were limited, females would prefer a specific male, indicating an active position in intersexual relationships. The guinea pig social structure was defined using the simple ratio association index and the social network analysis. Female preference was tested in a three partitions fenced , the central was empty and the laterals had a male restricted to it by guinea-pig collar. Females were free to move around all during 2 hours. Female preference analysis was made by comparisons between female time in each partition (Mann Whitney and Kruskal-Wallis, significance: 5%). Results showed that in colony females make intra and inter preferential associations, strongest among females-than among male-male or female-male in a higher number of individuals in the colony. In female-male associations, females had stronger relationship with two males from their colony. Results of preference tests reflect association preferences in colony: there were no difference in female time with the two prefered males of the colony. The third male was never chosen, and females prefered to spend more time in the empty partition. Results about social structure with association preferences, and in preference tests show the active role of females in intersexual associations and, possibly, in mate selection.

One of the more fascinating Darwinian puzzles in sexual selection is that of copulatory wounding. For those taxa displaying this behavior, and that does not engage in traumatic insemination, the function of wound infliction during copulation remains unknown. In this study, the intention was to evaluate the purpose of copulatory wounding in Drosophila melanogaster and the consequences it might have for male and female fecundity. The present study measured the size and number of wounds that males from different stocks of Darwinian fitness imposed on females, as well as the copulation duration and the resulting fecundity. The number of wounds and the total wound size showed no apparent correlation to fecundity, but a significant difference in variation of the number of wounds inflicted on females was observed between males from two different lines of fitness. Wounded females were also considerably more common than non-wounded females, as were wounds that were paired compared to non-paired copulatory wounds. The results suggests that wounding might be an adaptive male trait and a copulatory courtship interpretable to females, implying a possible case of cryptic female choice. Since most wounds were paired, this implies that a bilaterally symmetrical organ is causing these wounds. Also, wounding was not as important for fecundity as previously thought. / Ett av de mer fascinerande Darwinistiska pusslen inom sexuell selektion är skadande under kopulationen. För de taxa som uppvisar detta beteende, och inte engagerar sig i traumatisk insemination, så är funktionen av kopulationsskador okänd. I denna studie så var avsikten att utvärdera syftet av kopulationsskador hos Drosophila melanogaster och de konsekvenser beteendet kan ha för det resulterande antalet avkomma. Denna studie uppmätte storleken och antalet skador som hanar av olika Darwinistisk fitness vållade honor, samt kopulationstiden och antalet avkomma. Antalet skador och den totala storleken av skador visade ingen signifikant korrelation till antalet avkommor, däremot uppvisades signifikanta variationsskillnader mellan hanar av två olika fitnessnivåer. Skadade honor visade sig också vara betydligt vanligare än icke skadade honor och parade skador var även vanligare än icke parade skador. Resultaten indikerade att kopulationsskador kan vara en adaptiv egenskap hos hanar och en form av uppvaktning som honorna kan tyda, vilket kan antyda ett möjligt fall av ”kryptiskt honligt val”. Eftersom de flesta skador var parade, så antyder detta att ett bilateralt symmetriskt organ orsakar skadorna. Kopulationsskador visade sig heller inte vara så viktiga som man tidigare antagit.