Uniparental and biparental markers unravel invasion pathways, population admixture, and genetic structure in naturalized rainbow trout (Oncorhynchus mykiss).

The present study combined uniparental mtDNA and biparental SNPs to illuminate the invasion and colonization pathways of rainbow trout, Oncorhynchus mykiss, one of the world's most widespread invasive fishes, that has been intensively propagated in Chile, South America. The specific goals of the study were: (i) to evaluate potential donor populations, which could either be from the species' native range in North America or from introduced populations in Europe, by comparing mtDNA D loop/control region haplotypes; and, (ii) to assess the factors that have shaped genetic diversity and contemporary genetic structure of rainbow trout populations introduced to Chile through SNP genotyping. comprehensively sampled twenty-four sites in twelve basins ranging from the High-Andean Plateau (Altiplano, 18°S) to northern Patagonia (41°S). Results of the mtDNA data of naturalized trout populations from rivers in the Altiplano (northern Chile) differed from those collected in central and southern Chile suggested an origin from North American hatcheries. Naturalized trout populations in central and southern Chile, on the other hand, shared haplotypes with specimens found in European hatcheries. The southern and central Chile populations also contained rare haplotypes, possibly indicating potential spread through aquaculture escapes. Results of the SNP analysis revealed higher allelic richness for trout sampled in sites influenced by commercial aquaculture than sites without commercial aquaculture, likely due to increased admixture between aquaculture broodstock and naturalized trout. The analysis further uncovered some complex patterns of divergent trout populations with low genetic diversity as well as increased relatedness between individuals from isolated sites, suggesting possible local populations. A comprehensive characterization of genetic diversity and structure of rainbow trout should help identify management areas that may augment socio-economic benefits while prevent spread and further impacts on biodiversity. This article is protected by copyright. All rights reserved.