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Author: Joshua R. York Publisher: ISBN: Category : Collared lizards Languages : en Pages : 212
Book Description
"Sexual selection theory often predicts that socially dominant males should sire more offspring than males adopting subordinate social tactics. However, it is often difficult to determine the extent to which this expected distribution of male reproductive success is influenced by intra- and intersexual selection. Using a combination of field behavioral studies and molecular genetic techniques, I first tested the extent to which observations of social and spatial behavior predicted the distribution of reproductive success among female collared lizards and males displaying alternative social tactics (territorial and non-territorial) during a single reproductive season. I also examined the strength of sexual selection acting on male morphological and behavioral traits. Contrary to expectations, male social status did not accurately predict patterns of reproductive success: non-territorial males obtained reproductive success equal to that of territorial males and females were highly promiscuous, mating with a similar number of territorial and non-territorial males, both within and among successive clutches. None of the traits that I examined were significant targets of sexual selection among non-territorial males. However, male snout-vent-length was under positive directional selection among territorial males. To test the generality of my earlier findings, I expanded my analyses to encompass three seasons to examine how the number of female mates and offspring sired among males varied with marked natural variation in the intensity of intra- and intersexual selection within and among seasons, and the influence of behavioral traits on male fitness. I also examined how the degree of female promiscuity varied with changes in the intensity of sexual selection and the influence of female promiscuity on offspring survivorship. Unexpectedly, results from all seasons confirmed that non-territorial males consistently mated with similar numbers of females and sired similar numbers of offspring as territorial males. Moreover, females were promiscuous in all three seasons with similar numbers of territorial and non-territorial males. However, promiscuity decreased offspring survivorship. Together, my results suggest that mating relationships among collared lizards contrast sharply with predictions from classical mating system theory and likely represent the outcome of sexual conflict. Both sexual conflict and the high reproductive success of non-territorial males appear to be promoted by the homogeneous and continuous topography of the semi-natural habitat at my study site, which differs markedly from the natural habitat of collared lizards."--Abstract.
Author: Joshua R. York Publisher: ISBN: Category : Collared lizards Languages : en Pages : 212
Book Description
"Sexual selection theory often predicts that socially dominant males should sire more offspring than males adopting subordinate social tactics. However, it is often difficult to determine the extent to which this expected distribution of male reproductive success is influenced by intra- and intersexual selection. Using a combination of field behavioral studies and molecular genetic techniques, I first tested the extent to which observations of social and spatial behavior predicted the distribution of reproductive success among female collared lizards and males displaying alternative social tactics (territorial and non-territorial) during a single reproductive season. I also examined the strength of sexual selection acting on male morphological and behavioral traits. Contrary to expectations, male social status did not accurately predict patterns of reproductive success: non-territorial males obtained reproductive success equal to that of territorial males and females were highly promiscuous, mating with a similar number of territorial and non-territorial males, both within and among successive clutches. None of the traits that I examined were significant targets of sexual selection among non-territorial males. However, male snout-vent-length was under positive directional selection among territorial males. To test the generality of my earlier findings, I expanded my analyses to encompass three seasons to examine how the number of female mates and offspring sired among males varied with marked natural variation in the intensity of intra- and intersexual selection within and among seasons, and the influence of behavioral traits on male fitness. I also examined how the degree of female promiscuity varied with changes in the intensity of sexual selection and the influence of female promiscuity on offspring survivorship. Unexpectedly, results from all seasons confirmed that non-territorial males consistently mated with similar numbers of females and sired similar numbers of offspring as territorial males. Moreover, females were promiscuous in all three seasons with similar numbers of territorial and non-territorial males. However, promiscuity decreased offspring survivorship. Together, my results suggest that mating relationships among collared lizards contrast sharply with predictions from classical mating system theory and likely represent the outcome of sexual conflict. Both sexual conflict and the high reproductive success of non-territorial males appear to be promoted by the homogeneous and continuous topography of the semi-natural habitat at my study site, which differs markedly from the natural habitat of collared lizards."--Abstract.
Author: M. Catherine Duryea Publisher: ISBN: Category : Languages : en Pages : 214
Book Description
Sexual selection is a driver of biodiversity and creates spectacular forms of variation. However, only recently have we begun to understand how this variation operates on the postcopulatory level and how cryptic mechanisms affect male-male competition and female choice. Whenever a female mates with and stores sperm from multiple males, there is potential for fertilization to be biased. Brown anoles (Anolis sagrei) are exceptional in that females exhibit a fertilization bias with a known ecological basis. When mated multiply, females produce a higher proportion of sons from larger sires. This bias is adaptive in that sons from larger sires have higher survival in the wild. However, the mechanisms that underlie this bias are not known. Here, I take a three-pronged approached to exploring this cryptic fertilization bias. First, I develop an Approximate Bayesian Computational model to investigate effects of male mating order on their reproductive success. Second, I use a functional genomic approach to investigate the female genetic response to mating and uncover potential genetic candidates involved in postcopulatory sexual selection. Third, I use a three-year parentage dataset of a wild population of brown anoles to determine whether selection is acting antagonistically on male and female body size at the population level, which might further highlight the importance of cryptic processes for fertilization bias. Using Approximate Bayesian modeling, I find that the first male to mate has an advantage in Anolis sagrei. I also find that the model sometimes outperforms other statistical methods at detecting mating order biases. Secondly, I find that the female genetic response to mating in Anolis is complex; many genes are differentially expressed after mating. These genes show convergence to the genetic response to mating in Drosophila based on Gene Ontology. Additionally, I describe one serine protease gene (Stejnibrase) that shows evidence of positive selection. Lastly, I report evidence for sexually antagonistic selection on body size in Anolis sagrei based on a reproductive component of fitness. These results indicate that sexual conflict is a persistent force in this system and that mechanisms that resolve this conflict should be promoted by selection.
Author: Jennifer M. Gumm Publisher: ISBN: 9781109166828 Category : Languages : en Pages : 106
Book Description
In systems with alternative reproductive tactics (ARTs), males have discrete behaviors and morphologies that allow them to optimize their reproductive success in relation to others in the population. Males with different phenotypes directly compete with one another for mates, providing unique opportunities for studying social interactions within a species. Using the Comanche Springs pupfish, Cyprinodon elegans, a species with three alternative reproductive tactics, I examine how male behaviors and social interactions influence the reproductive success of each tactic.
Author: Rui F. Oliveira Publisher: Cambridge University Press ISBN: 1139469525 Category : Medical Languages : en Pages : 490
Book Description
The study of alternative reproductive tactics (the behavioural strategies used by individuals to increase their reproductive success) is an evolutionary puzzle, and one of great interest to researchers. For instance, why do some males guard both nest and eggs, while others sneak into nests while pairs are spawning and fertilise those eggs? The field offers a special opportunity to study the evolution and functional causes of phenotypic variation, which is a general problem in the field of evolutionary biology. By integrating both mechanistic (psychological) and evolutionary (behavioural ecology) perspectives and by covering a great diversity of species, Alternative Reproductive Tactics addresses this integrated topic of longstanding interest, bringing together a multitude of otherwise scattered information in an accessible form that is ideal for graduate students and researchers.
Author: Cody A. Braun Publisher: ISBN: Category : Crotaphytus collaris Languages : en Pages : 202
Book Description
Territory defense typically involves costly behavioral tactics that may detract from mating opportunities and other fitness enhancing activities. Selection on males therefore is expected to result in their establishing territories and adopting behavior patterns that maximize mating opportunities while simultaneously minimizing costs of spatial defense, which may vary among microhabitat patches that differ in physical parameters such as size, shape, and structural complexity. Using field behavioral studies, I first tested the influence of microhabitat patch structure (simple versus complex) on social and spatial behavior in territorial and non-territorial male eastern collared lizards (Crotaphytus collaris). As a result of markedly different structural conditions in the two microhabitat types, I proposed two alternative sexual selection models to explain factors that may govern male behavior and fitness. Despite the relatively small size and narrow dimensions of simple microhabitats, lizards colonized both simple patches, resulting in high local densities. Nevertheless, some males still defended territories on simple patches, and they did so without initiating contests with rivals or giving broadcast displays more frequently than territorial individuals on complex patches. By contrast, territorial males on simple patches moved throughout their territories more, and also courted a greater number of females more frequently than territorial males on complex patches. Non-territorial males in the two microhabitat types did not differ in any of the social variables measured. Increased visibility owing to the relatively flat and unobstructed surface topography of simple patches appears to promote increased courtship opportunities, while at the same time allowing males to deter same-sex competitors without significantly increasing costly defensive behaviors. Moreover, prioritization of courtship in highly competitive neighborhoods suggests that male behavior is shaped more by opportunities to interact with females than by competition for intrasexual dominant social status, perhaps because proximity to females coupled with simple habitat structure promotes monopolization of female mates. Although sexual selection theory predicts that socially dominant males will sire more offspring than males adopting subordinate social tactics, increased structural complexity of microhabitats may compromise the ability of territory owners to detect non-territorial rivals and prevent them from mating with female residents. To test the hypothesis that the ability of males to monopolize matings with females is negatively related to the structural complexity of microhabitats, I used molecular genetic techniques to quantify reproductive success for territorial and non-territorial males in each microhabitat type. Consistent with this prediction, males defending territories on simple patches sired a greater proportion of the offspring produced by individual mates compared to territorial males on complex patches. Contrary to the expectation that increased mate monopolization by territorial males would decrease mating opportunities for non-territorial males, neither the total number of offspring sired, nor the number of female mates differed as a function of male social status on simple patches, most likely as a result of high local female densities. By contrast, territorial males on complex patches sired more offspring total than their non-territorial rivals, and also tended to mate with more females (but not statistically so). The observation that territorial males on simple microhabitats sired a larger proportion of the offspring produced by their female mates compared to territorial males on complex patches suggests that mate monopolization may be more feasible in microhabitats that are less structurally complex because they afford territory owners high visibility while also limiting undetected movement by non-territorial males. Higher levels of mate monopolization without increased defense costs suggests that territory defense may be more economical in structurally simple microhabitats. Because the simple human-constructed microhabitats at this study site mimic some features of the natural rock outcrops and washes on which the socio-spatial behavior of collared lizards evolved, these results are more similar to what might be expected in populations in natural habitats.
Author: Justin L. Rheubert Publisher: CRC Press ISBN: 1466579870 Category : Nature Languages : en Pages : 742
Book Description
Reproductive Biology and Phylogeny of Lizards and Tuatara is a remarkable compendium of chapters written by the world's leading experts from over four continents. The book begins with a chapter recounting historical discoveries in reproductive biology and a review of phylogenetics and up-to-date hypotheses concerning evolutionary relationships amon
Author: Stephen M. Shuster Publisher: ISBN: 9780691049304 Category : Science Languages : en Pages : 533
Book Description
Presenting a unified conceptual and statistical framework for understanding the evolution of reproductive strategies, this text uses the concept of the opportunity for sexual selection, illustrating how and why sexual selection is one of the strongest and fastest of all evolutionary strategies.
Author: Joshua R. York
Author: Joshua R. York
Author: M. Catherine Duryea
Author: Jennifer M. Gumm
Author: Daniel W.A. Noble
Author: Mats Olsson
Author: Rui F. Oliveira
Author: Cody A. Braun
Author: Justin L. Rheubert
Author: Ammon Corl
Author: Stephen M. Shuster