The Effects of Neutral and Adaptive Evolutionary Processes on Genetic and Phenotypic Variation in Small Populations of Icelandic Arctic charr (Salvelinus alpinus)

I examined Arctic charr (Salvelinus alpinus) sampled from 19 lava caves near Lake Mývatn, Iceland to assess the hypotheses that patterns of genetic and phenotypic variation are affected by: (i) colonization history; (ii) genetic drift and gene flow coupled with contemporary landscape features; and (iii) divergent natural selection caused by ecological variation as an agent of selection. I detected significant signatures of colonization history based on the genetic clustering of the cave populations and their relationship to the lake fish. Signatures of genetic bottlenecks and the association of genetic variation with geography and population size suggest that genetic drift has contributed to population divergence. Estimates of gene flow and fish movement are positively related to the geographic proximity of populations. In contrast, I found limited evidence that patterns of genetic and phenotypic variation are related to ecological variation.