Fitness maps to a large-effect locus in introduced stickleback populations
Dolph Schluter, Kerry B. Marchinko, Matthew E. Arnegard, Haili Zhang, Shannon D. Brady, Felicity C. Jones, Michael A. Bell, David M. Kingsley
Abstract
Significance The role of mutations of large effect in adaptive evolution is a question of enduring interest. Large-effect mutations were once seen as unlikely contributors to adaptation, but we now have numerous examples. A major shortcoming of the evidence is the lack of information on fitness effects of mutations. We conducted a quantitative trait locus study that mapped fitness in an experimental field population of stickleback to a large-effect gene, Ectodysplasin ( Eda ). We compared this result with allele frequency change at the gene in a young lake population, which also revealed strong natural selection and large fitness effects of the Eda gene and/or linked genes. Selection on ancient genetic variants may increase the prevalence of large-effect fitness variants in adaptive evolution.