Modelling contemporary evolution in stickleback

Abstract

During the past decade, two lines of research have advanced our understanding of micro‐evolution. On the one hand, a number of studies have generated evidence for strong selection on phenotypes (Kingsolver et al. 2001) and the contemporary (sometimes deemed ‘rapid’) evolution of phenotypic traits (Hendry & Kinnison 1999). On the other hand, other studies have sought to identify the genes that underlie ecologically important traits (Ungerer et al. 2008). Over the next decade, micro‐evolutionists might expect considerable progress from the study of contemporary evolution at both the phenotypic and genetic level simultaneously. In this issue of Molecular Ecology, Le Rouzic et al. (2011) present a teaser for this approach. They examined contemporary evolution of an adaptive trait with a well‐studied genetic basis, the number of lateral plates, in threespine stickleback (Gasterosteus aculeatus L.). A time series of 20 years of change for this trait after introduction into a pond in Norway was compared with a similar time series of 12 years following the invasion of a lake in Alaska. Using a modelling approach, the authors then teased apart selection acting upon the phenotype and selection acting on a major effect gene. In both time series, selection was strong and consistent. The models suggested that selection could act directly on the phenotype, or through the gene’s pleiotropic effects.