EAPSI: Evolutionary Origins of Complexity in a Bioluminescent Crustacean

Ellis Emily A, Santa Barbara CA

Investigators

Abstract

A long-standing question in evolutionary biology is why there are so many species. One possibility is that certain traits ¬including courtship displays ¬contribute to a faster rate of new species formation (speciation). Although studied for decades, there are still only a few well-documented examples of traits that led to faster speciation, and even fewer that implicate sexual traits as a driver of speciation. Without well-documented examples, it is impossible to distinguish between different explanatory models that link particular traits to rapid speciation. A novel, but tractable, study system to investigate the link between sexual selection and speciation is ostracod crustacean bioluminescence. Many of these animals use bioluminescence in a courtship display, not unlike fireflies. This award supports collection and genetic and behavioral analysis of a diverse range of bioluminescent ostracod crustaceans to determine whether female preference for light pre-dates the evolution of male light signals. The answer to this question has direct implications for models of how mating signals evolved. The research will be conducted in collaboration with Dr. Yoshihiro Ohmiya, a noted expert on invertebrate bioluminescence, at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan. This project bridges the gap between molecular phylogenetics and behavioral evolution. The proposed research offers a novel approach to studying female preference in a phylogenetic context, as well as functional tests to discover previously undocumented conspecific bioluminescent signals. The award supports collection of eleven Japanese bioluminescent ostracod crustaceans and their close relatives (none of which use bioluminescence for mating). The collection will enable genetic, species-level data for a novel phylogeny to test various sexual selection hypotheses. This will be augmented by behavioral studies that quantify female response to simulated bioluminescence. These results will be synthesized to time the origins of the male signaling trait and the evolution of female preference. The researcher will test the Sensory Exploitation Hypothesis, which posits that traits involved in mating exploit the receiver?s innate senses. After these experiments, the ostracods will be preserved for further genomic study. Genomic material will be sequenced to create a phylogenetic tree of relationships for the group and test whether the evolution of bioluminescent courtship displays has increased diversity in the group. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.