DISSERTATION RESEARCH: The Evolutionary Genomics of Facultative Social Behavior in a Tropical Sweat Bee

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

ABSTRACT PI Nonacs CoPI Wayne Proposal #IOS-0808256 THE EVOLUTIONARY GENOMICS OF FACULTATIVE SOCIAL BEHAVIOR IN A TROPICAL SWEAT BEE Evolutionary explanations for altruism have been sought since the time of Darwin, and are still not agreed upon by many researchers. Cooperation is most extreme within social insect colonies, in which one or a few members (queens) reproduce, and most colony members (workers) forego reproduction to specialize in other tasks. One explanation for social evolution is based on the similarities between social insect worker behavior and maternal reproductive traits. The worker caste may have originated in a solitary ancestor when a mutant female exhibited maternal behavior prior to dispersal. This would have resulted in sibling-directed, instead of offspring-directed care. If this theory is correct, genes active throughout the reproductive cycle of solitary ancestors should be differentially regulated in workers and queens of social descendants. An ideal test of this hypothesis requires knowledge of gene expression patterns in representatives of the social and ancestral solitary state. Fortunately an analogous condition exists in Megalopta genalis bees, where both social and solitary individuals are found simultaneously within the same population. To analyze differential gene expression, a custom microarray, (a slide containing probes corresponding to approximately 5,000 genes expressed in the M. genalis brain) will be created. Because sociality in M. genalis is flexible and aseasonal, this proposal represents a better controlled and more informative study than is possible in any species studied to date. The results will highlight evolutionary pressures consistently important to the origin of eusociality, and have a transformative role in understanding how the social environment affects reproductive behavior. Broader impacts of the work: The new large-scale genomic resource created within this proposal will be publicly available, and useful to other researchers from many scientific disciplines. The proposed laboratory work will provide training in cutting edge molecular techniques to undergraduate students through an ongoing UCLA program aimed at increasing minority participation in scientific research.