26 Oral - Evolution I
Thursday April 07, 5:00 PM - 5:15 PM
Cis-regulatory Changes at the Fatty Acid Elongase eloF Underlie the Evolution of Sex-specific Pheromone Profiles in Drosophila Prolongata
Authors: Yige Luo 1; Ayumi Takau 2; Takashi Matsuo 2; Santiago Ramirez 1; Artyom Kopp 1
Affiliations: 1) University of California, Davis; 2) Tokyo University, Tokyo
Keywords: n. genotype to phenotype; e. enhancers
Binary communication systems involving signaling and signal perception play a key role in sexual selection and in the evolution of sexually dimorphic traits. The selective forces and genetic changes underlying such traits can be studied in systems where sex‐specific signaling and perception have emerged recently and show signs of coevolution. A promising model is found in Drosophila prolongata, which exhibits a species‐specific increase in the number of male gustatory bristles. We find that this transition coincides with a change in cuticular hydrocarbon (CHC) profiles. D. prolongata males show increased amounts of the long-chained 9‐pentacosene (9P) and 9‐heptacosene (9H), and a coincident decrease in the shorter-chained 9‐tricosene (9T), compared to females. This is in contrast with the closest relatives of D. prolongata, in which these CHCs are sexually monomorphic. Perfuming D. prolongata females with 9P or 9H reduces copulation success, suggesting that they act as sex pheromones. To unravel the genetic mechanism responsible for evolutionary transition from sexually monomorphic to dimorphic production of these mono‐alkenes, we sequenced the oenocyte transcriptomes from males and females of D. prolongata and its relative D. carrolli. The top candidate gene that emerged from this analysis is elongaseF (eloF), which encodes an enzyme responsible for fatty acid elongation. eloF shows elevated expression in D. prolongata males, consistent with the male-specific enrichment of long-chain CHCs in this species. Male-biased eloF expression in D. prolongata appears to be associated with a species-specific insertion of a transposable element (TE) at this locus. We are currently testing this hypothesis using chimeric reporter constructs that carry a combination of D. prolongata and D. carrolli sequences. Our results suggest that pheromone synthesis may have coevolved with chemosensory perception and suggest a possible molecular mechanism for the evolution of male-female communication.