Sexual selection and biological diversification: Patterns and processes
AuthorMesnick, Sarah Lynne, 1960-
AdvisorThomson, Donald A.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThis dissertation investigates the evolutionary consequences of three very different behavioral mechanisms by which males may bias female mating decisions in their favor, elaborate male displays (Chapters I and II) and sexual coercion and resource brokering (Chapter III). The results presented here suggest that sexual selection is an important force in evolution. In Chapters I and II, I investigate the relationship between male courtship displays and speciation. Chapter I utilizes the multiple sister-taxa comparison method to test the hypothesis that sexual dimorphism is correlated with increased species diversity in teleost fishes. In 21 of 27 sister-group comparisons, the lineage with the greater degree of sexual dimorphism was more species-rich than its hypothesized sister taxa. The pattern holds across taxonomic levels and sensory modalities, and whether the male, or the female, is the displaying sex. Additional data supporting the sexual selection-diversity hypothesis in other taxa are also discussed. Chapter II investigates how variation in the signals displayed during social and sexual interactions affect reproductive isolation and may facilitate subsequent speciation, utilizing both field and laboratory experiments with the marine fish, Acanthemblemaria crockeri, a chaenopsid blenny endemic to the Gulf of California, Mexico. The anterior portion of the body, the "signal organ", displayed during social interactions, was found not only to be the most variable but was also the most geographically informative. The behavioral responses of the fish themselves, in both male courtship discrimination trials and in female spawning trials, reinforce these geographical differences and results suggest that variation in socially selected traits may accelerate reproductive isolation. In Chapter III, I examine how, if some males in a population use force to bias female mating decisions, protection can become a valuable resource that other males can use to attract females. I term this the bodyguard hypothesis of female mate choice. I present data illustrating the effectiveness of protective males in reducing the probability of aggression from other males and suggest the importance of protective mating alliances in the evolution of a diversity of animal mating systems including mate guarding, leks, "harems", monogamy, polygyny, and pair-bonding in humans.
Degree ProgramGraduate College
Ecology & Evolutionary Biology