local adaptation

Nielsen EE, Hemmer-Hansen J, Larsen PF & Bekkevold D 2009 Population genomics of marine fishes: identifying adaptive variation in space and time. Mol Ecol 18:3128-3150.

• despite 40 years of research effort, good examples of genetic polymorphisms maintained by environmental heterogeneity among natural populations are not particularly numerous
• this is not surprising, given that the power to detect selection on a trait is limited when large numbers of loci contribute to the phenotypic variation (see discussion in Storz 2005), as expected for many quantitative traits undergoing local adaptation