Analysis of the Effects of Variations in Chemosensory Genes in Drosophila

Undergraduate: Bhairavi Rajasekar

Faculty Advisor: Corbin Jones
Department: Biology

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Our research examines the adaptation and evolution of preference for one food environment. The toxic effects of octanoic acid, a compound produced by the fruit of Morinda citrifolia, is lethal to most fruit flies. However, some fruit flies such as Drosophila sechellia have developed a resistance to the compound and are able to thrive on this host plant. Drosophila that prefer fruits with more fatty acids are considered the specialist species while those that display no particular preference are generalists. While this trait involves several genes, a key evolutionary shift was potentially made possible by a mutation occurring in a chemosensory receptor that changed how the flies respond to the food. We hypothesize that a chemosensory gene, Gr22c, has evolved and allows these flies to be attracted environments with high concentrations of octanoic acid. The research used transgenesis to create chimeric versions of the generalist species that contain alleles of a specialist species. Virgins of these species were set up in a controlled bio assay, containing an acidic food medium and a control food medium. After 24 hours, the flies in the acidic environment were quantitatively compared against the flies that preferred the control environment, evaluating the sex and status of the fly as alive or dead. The overall goal is to investigate the relationship between the adaptations and food preferences.