CHEMICAL COMMUNICATION AND SPECIATION IN HAWAIIAN CRICKETS
Stamps, Glenn Francis
The main objective of this doctoral dissertation is to explore the role chemical communication may play in the diversification of the Hawaiian swordtail crickets (genus Laupala). Laupala are known for their diversification in male acoustic signaling and associated female preferences. They also possess a complex courtship which includes extensive antennal interaction and during which the male gives nuptial gifts. Despite historically being seen as indiscriminate, males are predicted to make mating decisions under certain circumstances, such as when males are limited in the resources they are able to invest in females. Given that females are silent, males are likely using some other signaling modality, such as through contact pheromones on the antennae. Here, I tested the male use of chemical cues in initiating mating decisions, the impact of these cues on species boundaries, and how pheromones may be evolving in relation to song. Using both gas chromatographic analysis and novel behavioral assays, I examined the hypothesis that male L. pruna are using chemical signals to distinguish between males and females. I found that males and females differed quantitatively in their expression of shared peaks. Further, access to the antennae alone was sufficient cause aggressive behavior or courtship behavior towards males and females, respectively. I tested the hypothesis that males are using chemical information to distinguish between species. I used L. pruna and a closely related species, L. kohalensis, and found low interspecific mating success. Chemical analysis also determined that these species differed in their pheromone profiles. Males initiated courtship in the presence of conspecific, but not heterospecific female antennae. I explored the hypothesis that male song and CHC expression are evolving together. I found significant heterogeneity among populations in both signals. The distribution of these signals follows the nonlinear ages of the volcano, versus a simple isolation-by-distance model. Together, these experiments establish chemical communication in male mate choice, demonstrate that differences in chemical expression matter for species boundaries, and suggest that acoustic and chemical signals may be coevolving early in the speciation of Laupala.
male mate choice; speciation; Behavioral sciences; Evolution & development; Biogeography; chemical communication; Entomology
Shaw, Kerry L.
Seeley, Thomas Dyer; Raguso, Robert A.
Neurobiology and Behavior
Ph. D., Neurobiology and Behavior
Doctor of Philosophy
dissertation or thesis