Data From: Polygenic basis and the role of genome duplication in adaptation to similar selective environments

Genetic changes underlying adaptation vary greatly in terms of complexity and, within the same species, genetic responses to similar selective pressures may or may not be the same. We examine both complex (supergene) and simple (SNP) genetic variants occurring in populations of rainbow trout (Oncorhynchus mykiss) independently isolated from ocean access and compared them to each other and to an anadromous below-barrier population representing their ancestral source to search for signatures of both parallel and non-parallel adaptation. All landlocked populations displayed an increased frequency of a large inversion on chromosome Omy05, while three of the four populations exhibited elevated frequencies of another inversion located on chromosome Omy20. In addition, we identified numerous regions outside these two inversions that also show significant shifts in allele frequencies consistent with adaptive evolution. However, there was little concordance among above-barrier populations in the...