Genetic basis of natural variation in cuticular hydrocarbons in the Drosophila melanogaster Genetic Reference Panel. Lauren Dembeck^1,3, Katalin Böröczky^2,3, Michael Maguire^1,3, Richard Lyman¹, Coby Schal^2,3, Trudy Mackay^1,2,3. 1) Department of Genetics, North Carolina State University, Raleigh, NC; 2) Department of Entomology, North Carolina State University, Raleigh, NC; 3) W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC.

   Drosophila melanogaster mate choice is strongly influenced by the presence of contact pheromones, which consist of cuticular hydrocarbons (CHCs), on the insect's cuticle. Hence, variation in CHCs can potentially alter mate choice leading to assortative mating and incipient speciation. We studied natural variation in CHCs using the Drosophila melanogaster Genetic Reference Panel (DGRP). The DGRP is a panel of inbred lines of D. melanogaster derived from a natural population at the Raleigh, NC, Farmer's Market. Complete genome sequences are available for the lines, which enable genome-wide association (GWA) analyses to uncover the genetic basis of natural variation in CHCs. We collected gas chromatography spectra of DGRP flies and quantified relative abundance of CHC components for both sexes. We identified 69 female and 36 male CHCs, including several dienes and methyl alkanes that were not previously described. A majority of the CHCs show heritable phenotypic variation including the known pheromonal compounds. Our preliminary GWAs did not identify obvious candidate genes; however, we find polymorphisms in or near many genes not previously known to affect natural variation in CHCs. Finally, we conducted correlation analyses of variation in CHCs with other traits such as mate choice and aggression. These results may offer insight into the link between variation in pheromone blend with behavior and incipient speciation.