The Evolution of Mate Choice in the Genus Limia

Mate choice is a discipline of sexual selection research describing the process of an individual biasing resource use to reproduce with preferred mates. Classical theory describes mate choice as only occurring in females or extreme cases, such as sex-role reversal. However, mounting evidence of male mate choice in various animal systems has since debunked this theory. Although male mate choice occurs in many taxa, empirical studies examining the factors that shape male choice are lacking. Theory suggests that male preference can persist if the benefits of mating with high-quality females outweigh the costs of mate choice. Given that many males have evolved elaborate secondary sexual traits (SST), such as ornaments, armaments, and courtship displays, we sought to understand how male SST influence mate choice in polygynous mating systems (i.e. populations were males and females mate multiple times). We predicted more elaborate SST should select for more exaggerated preferences for high quality mates. To test my prediction, we examined how interspecific and intraspecific variations in SST impacted mate choice in the genus Limia. Limia is an understudied group of livebearing fishes endemic to the Caribbean, with many mating strategies. In both my intraspecific and interspecific mate choice experiments, we found a lack of preference in both males and females regardless of male SST, except for the species with minimal male SST. These results were unusual because both male and female choice, which has been widely described in livebearing fishes, were absent in multiple species. We began to suspect that Limia’s unique preferences were a product of their unique geographic distribution. Limia are native to four islands in the Greater Antilles: Cuba, Hispaniola, Jamaica, and Grand Cayman. Biogeography theory predicts island landmass is positively correlated with species diversity, suggesting Cuba should host the greatest diversity of Limia species. However, of the 22 species of Limia, 19 are on Hispaniola, the second largest island, while only one species is on each of the other islands. To begin understanding if this unusual pattern influenced mate preference, we constructed a phylogeny (i.e., a computational hypothesis of the evolution of a group of organisms based on genetic similarities) of Limia. We found evidence of two relatively recent radiation events on Hispaniola; however, further work is necessary to determine if these have impacted mate choice in this group