FROM THE COVER Adaptation of Drosophila to a environment reveals temporall s

l en ition ed ge s th duri generations, we identified a pronounced genomic response to selection, with almost 5000 Introducti One of the understand used to stu three catego ics; and (ii quantitative tionary biologists who study the genetic architecture of son et al. 2004; Mackay et al. 2009). More recently, gen-. These no stead take t break up pping and ngths and ods is that aptive nat-proach, in contrast, does not require any a priori information about Nielsen 2005). While this approach is conceptually Molecular Ecology (2012) 21, 4931–4941 doi: 10.1111/j.1365-294X.2012.05673.xome-wide association studies have become popular appealing, it has become increasingly clear that complex demographic histories that involve migration and popu-lation bottlenecks can generate a signature in the genome that cannot be distinguished from selection (Thornton et al. 2007; Parsch et al. 2009). A completely different approach towards understand-ing adaptation is pursued by experimental evolutio