Evolutionary Genomics of Introduced Salmonid Species in Patagonia, South America

Invasive species have become widespread in aquatic environments throughout the world, yet there are few studies that have examined the genetic mechanisms that allow for successful invasion of newly colonized environments.  In this study we contrast genomic variation in two salmonid species (Oncorhynchus tshawytscha, 11,579 SNPs; Salvelinus fontinalis, 13,522 SNPs) with differing invasion success after introduction to new environments in South America relative to populations from their native range in North America.  Estimates of genetic diversity were not significantly different between introduced and source populations for either species, indicative of propagule pressure that has previously been shown to maintain diversity in founding populations of invasive species relative to their native range.  Introduced populations also demonstrated higher connectivity and gene flow than those in their native range.   Evidence for local adaptation was observed within specific introduced populations, and appeared to be driven largely by selection on standing genetic variation.  Overall, patterns of genomic variation were consistent with broad or narrow life history variation in each species, and in combination, these factors contribute to invasion success of these two salmonids to novel environments.  These results provide further understanding of adaptation and invasion success of introduced species and may help guide management strategies.