ebonyaffects pigmentation divergence and cuticular hydrocarbons inDrosophila americanaandD. novamexicana

Abstract

1AbstractDrosophilapigmentation has been a fruitful model system for understanding the genetic and developmental mechanisms underlying phenotypic evolution. For example, prior work has shown that divergence of thetangene contributes to pigmentation differences between two members of the virilis group:Drosophila novamexicana, which has a light yellow body color, andD. americana, which has a dark brown body color. Quantitative trait locus (QTL) mapping and expression analysis has suggested that divergence of theebonygene might also contribute to pigmentation differences between these two species. Here, we directly test this hypothesis by using CRISPR/Cas9 genome editing to generateebonynull mutants inD. americanaandD. novamexicanaand then using reciprocal hemizygosity testing to compare the effects of each species’ebonyallele on pigmentation. We find that divergence ofebonydoes indeed contribute to the pigmentation divergence between species, with effects on both the overall body color as well as a difference in pigmentation along the dorsal abdominal midline. Motivated by recent work inD. melanogaster, we also used theebonynull mutants to test for effects ofebonyon cuticular hydrocarbon (CHC) profiles. We found thatebonyaffects CHC abundance in both species, but does not contribute to qualitative differences in the CHC profiles between these two species. Additional transgenic resources for working withD. americanaandD. novamexicana, such aswhitemutants of both species andyellowmutants inD. novamexicana, were generated in the course of this work and are also described. Taken together, this study advances our understanding of loci contributing to phenotypic divergence and illustrates how the latest genome editing tools can be used for functional testing in non-model species.