Population genetic structure of Patagonian toothfish ( Dissostichus eleginoides) in the Southeast Pacific and Southwest Atlantic Ocean

PeerJ. 2018 Jan 16;6:e4173. doi: 10.7717/peerj.4173. eCollection 2018.

Abstract

Previous studies of population genetic structure in Dissostichus eleginoides have shown that oceanographic and geographic discontinuities drive in this species population differentiation. Studies have focused on the genetics of D. eleginoides in the Southern Ocean; however, there is little knowledge of their genetic variation along the South American continental shelf. In this study, we used a panel of six microsatellites to test whether D. eleginoides shows population genetic structuring in this region. We hypothesized that this species would show zero or very limited genetic structuring due to the habitat continuity along the South American shelf from Peru in the Pacific Ocean to the Falkland Islands in the Atlantic Ocean. We used Bayesian and traditional analyses to evaluate population genetic structure, and we estimated the number of putative migrants and effective population size. Consistent with our predictions, our results showed no significant genetic structuring among populations of the South American continental shelf but supported two significant and well-defined genetic clusters of D. eleginoides between regions (South American continental shelf and South Georgia clusters). Genetic connectivity between these two clusters was 11.3% of putative migrants from the South American cluster to the South Georgia Island and 0.7% in the opposite direction. Effective population size was higher in locations from the South American continental shelf as compared with the South Georgia Island. Overall, our results support that the continuity of the deep-sea habitat along the continental shelf and the biological features of the study species are plausible drivers of intraspecific population genetic structuring across the distribution of D. eleginoides on the South American continental shelf.

Keywords: Abyssal depths; Antarctic circumpolar current; Deep-sea environment; Gene flow; Genetic connectivity; Genetic differentiation; Geographical isolation; Microevolution.

Grant support

This work was funded by Fondo de Investigación Pesquera (FIP 2006-41); and supported by the Fondo Nacional de Desarrollo Científico y Tecnológico de Chile (FONDECYT grant number: 1140692, 1170815, 3150456 and 1170486). Sandra Ferrada-Fuentes was supported by doctoral fellowships for the ‘Programa de Doctorado en Sistemática y Biodiversidad’, from the graduate school of the Universidad de Concepción, Chile and by a CONICYT doctoral fellowship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.