Dissertation Research: Evolution of Outcrossing and Sex Ratio in Caenorhabditis elegans

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This research aims to impart an evolutionary and ecological perspective onthe study of a model organism, the nematode Caenorhabditis elegans. In thisnematode, hermaphrodites--individuals with male/female reproductive organs--mayreproduce alone or via fertilization from males. This research seeks to elucidatethe role of males in this species and to explore general features involvedin the evolution of outcrossing. In particular: what proximate and ultimateforces influence the ability of males to persist, and at what frequencies? These issues will be addressed by (1) using molecular methods to determinethe frequency of males in large lab and natural populations, and (2) performinglab selection experiments to test hypotheses for the maintenance of outcrossing.This work will provide one of the first evolutionary ecological perspectivesfor C. elegans. This species has been subject to intensive study from genetics(the first animal genome sequenced) and developmental biology (all cell fatesare mapped between zygote and adult), but disproportionately little informationis available regarding its ecology and the processes underlying the evolutionof its unusual breeding system. This research will integrate multiple complementaryapproaches to characterize a more resonant description of ecology and evolutionin this model organism, and bear on general issues in the study of evolutionrelating to the evolution and maintenance of outcrossing.