PRJNA173879
Comparative QTL mapping of photoperiodic response in the pitcher-plant mosquito, Wyeomyia smithii
Identifying regions of the genome contributing to phenotypic evolution often employs genetic mapping of quantitative traits. The focus then turns to identifying regions of “major” effect, overlooking the observation that traits of ecological or evolutionary relevance often involve many genes whose individual effects are small but whose cumulative effect is large. Our approach uses QTL mapping of photoperiodic response to determine the distribution not only of major regions of the genome, but also apparently ‘non-significant’ regions that often, in reality, comprise the actual basis for the evolution of complex traits. We use the power of fully interfertile natural populations of a single species of mosquito that have diverged over both relatively short (post-glacial) and long (interglacial) time spans. We show that between recently diverged, post-glacial populations, individual marker regression coefficients show the signature of strong directional selection. Analogous comparison with marker regression coefficients from an ancient, unglaciated population shows the signature of balancing selection. While these differences might reflect polymorphisms within populations, we also propose that the mode of selection acting on diverging populations in nature can be reflected by patterns of individual marker regression coefficients as well as the major QTL.