A”tail”of two flies: the genetic basis of interspecific differences in abdominal pigmentation

WOMACK MM; REBEIZ M; FRANKEL N; HANNA A; STERN DL

Chicago

Congreso; 50th Drosophila Research Conference; 2009

One of the central goals of evolutionary biology is to elucidate processes that underlie the generation and diversification of phenotypes. Despite the importance of quantitative traits, surprisingly little is known about the evolutionary forces that shape them. While Drosophila yakuba presents the typical abdominal pigmentation pattern of the D. melanogaster subgroup, Drosophila santomea has lost most pigmentation in the abdomen. In this project I examine the genetic basis of the evolution of abdominal pigmentation differences between these two species. Here I present how this quantitative trait can be decomposed in individual Mendelian-like effects allowing for significantly higher resolution mapping of all major genetic factors than can be achieved with traditional QTL mapping. Through repeated backcrossing and selection, I generated introgression lines presenting distinct abdominal pigmentation patterns. Using these lines, I show: 1) how three of the four QTLs previously identified generate discrete, traceable pigmentation phenotypes and behave similarly to Mendelian loci; 2) how through mapping of the introgressions carried in these lines I have narrowed all four QTLs to a fraction of their original size, in some cases to an interval up to 3 orders of magnitude smaller; 3) how with this method it is possible to identify multiple genes underlying a QTL. Identifying the genetic basis of morphological differences between closely related taxa might help us to better understand patterns of morphological evolution. Such studies are likely to pinpoint important mechanisms generating variation in morphological characters from a conserved set of genes.