Molecular Genetics of Natural Populations

Significant progress in evolutionary genetics has been made by studying, on the one hand, patterns of DNA sequence polymorphism and, on the other, genetic architecture of complex adaptive traits. However, connections between nucleotide variants under selection and adaptively relevant phenotypes are missing. Such connections can be established using precise gene replacement. We review the recent successful introduction of this technique to the analysis of two evolutionarily interesting loci--Odysseus and desaturase2. Both genes have subtle phenotypes that nevertheless could be identified using gene replacement, demonstrating that effects of naturally occurring alleles can be measured in the laboratory. This is an important first step in connecting statistical signatures of selection with adaptation in nature. More candidate genes involved in adaptation, for example, through cloning of genes responsible for reproductive isolation, now need to be identified. Molecular genetic manipulation, DNA polymorphism analysis, and field studies then have to be integrated to provide fresh insights into the mechanisms of evolutionary change.