View Program - 63rd Annual Drosophila Research Conference

Reproductive traits are some of the most rapidly evolving traits within species, and some of the most rapidly diverging traits between nascent species. Sex-specific enhancer pleiotropy can provide a base for male and female coevolution. Here, we study two genes, Pox neuro (Poxn) and CG14567, that specify the morphology of a male-specific reproductive structure. The epandrial posterior lobes (ePLs) are novel reproductive structures on the male genitalia that are structurally important for mating success. In addition, morphological variation in shape and size of the ePL affects the male’s mating success and mating position. When males with a smaller or misshapen posterior lobe mate with a normal female, the female reduces her egg-laying amounts. Previous studies show that Poxn directs aspects of male courtship behavior and genital development, and recent studies from our lab show that variation in expression level of CG14567 in the developing ePL primordia directs variation in genital morphology among members of the D. melanogaster species complex.
Interestingly, one Poxn enhancer region that directs expression in the developing male genitalia is also expressed in three neurons in the adult female abdominal ganglion. These three neurons enervate the female reproductive tract as well as regions of the gastric tract. This Poxn enhancer is also expressed in collections of cells throughout the female VNC and Brian, but compared to males the domain of expression is much reduced. Our preliminary in-situ experiments show that CG14567 is also expressed in the brain and VNC of adult females and appears to localize to these Poxn-expressing neurons. We are currently working on behavioral assays to pinpoint the exact function of three neurons in the abdominal ganglion and we are using the GFP Reconstitution Across Synaptic Partners (GRASP) technique to identify the presynaptic cell(s) to these neurons in the females. Our initial functional genetic experiments show that both Poxn and CG14567 expression in these neurons affect female reproduction. In particular, overexpression of CG14567 in Poxn expressing cells increases the eggs laid by the female. Our preliminary genetic and behavioral data suggests that enhancer pleiotropy at Poxn and CG14567 could contribute to coevolution of reproductive traits.

Pleiotropy and the rapid coevolution in reproductive traits in Drosophila