Understanding the colonization history of Chinook salmon in Patagonia using single nucleotide polymorphisms (SNPs): gauging the effects of artificial transplants vs. natural dispersion

CAÑAS-ROJAS DIEGO; SEEB, L.W.; CARLA RIVA ROSSI; JAVIER CIANCIO; MIGUEL PASCUAL; SEEB JE; ERNST BILLY; DANIEL GOMEZ-USCHIDA

Portland

Conferencia; 2015 Annual Meeting of the American Fisheries Society; 2015

American Fisheries Society

Chinook salmon (Oncorhynchus tshawytscha) in South America have shown a rapid  history of colonization among Patagonian Rivers, likely mediated by both artificial transplants (1970 ? 1991) followed by dispersion from either farmed broodstock or established (naturalized) populations in more recent years (1991 ? Present). We genotyped 270 Chinook salmon sampled between 2003 and 2013 from eight Patagonian basins (six from Chile and two from Argentina) through a panel of 190 SNPs developed for native populations. Using population- and individual-based inference, our goal was three-fold: (1) quantify the contribution of source (native) populations on established populations, (2) identify the number of gene pools among established populations using Bayesian inference, and (3) test for signals of reduced diversity among Argentinian populations, which were presumably founded from a reduced number of immigrants. We found (1) variable contributions from native population sources among basins, consistent with records of early transplants and more recent imports for farming; (2) three genetic pools that corresponded to northern Patagonia, southern Patagonia and Argentina?s basins, in line with both artificial transplants and natural dispersion; (3) lower genetic diversity among Argentina?s Atlantic basins than Chile?s basins, suggesting a founder effect from Chinook salmon strays from the Pacific. These findings imply that a combination of both artificial and natural propagation might explain the rapid colonization of Chinook salmon in South America.