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

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.

Taxonomic re‐appraisal for toothfish (Dissostichus: Notothenioidea) across the Antarctic Polar Front using genomic and morphological studies

“…Numbers below bar correspond to locations; 1: Chile; 2: Falklands; 3: High Seas; 4: South Georgia; 5: SSI Second, RADSeq SNP genotyping confirmed nuclear differentiation and thus restricted bi-parental gene flow, between the samples on either side of the APF. This aligns with the differentiation reported by previous studies using microsatellites(Canales-Aguirre et al, 2018;Rogers et al, 2006) and confirms that the nonsignificant nuclear differentiation reported byShaw et al (2004) reflected insufficient statistical power rather than male biased gene flow per se. The higher statistical power conferred by RADSeq also permitted robust assignment of individuals to population of origin.Furthermore, outlier analysis identified individual SNPs exhibiting levels of divergence beyond neutral expectations in comparisons between samples across the APF, with no outliers identified when tests were restricted to comparisons among the Patagonian or South APF sites only: this pattern is compatible with divergent natural selection effects across the APF.…”

“…Genetic studies of toothfish have provided robust evidence of restricted genetic exchange between populations in Chilean and Patagonian waters, to the north of the APF, with populations south of the APF. Allozyme and microsatellite DNA markers have revealed significant nuclear differentiation between the Falkland Islands and populations south of the APF around Shag rocks and South Georgia (Appleyard et al ., 2004; Canales‐Aguirre et al ., 2018; Rogers et al ., 2006). Mitochondrial DNA restriction fragment length polymorphism (RFLP) analysis also reported a high level of mtDNA divergence between samples collected around the Falkland Islands and sites south of the APF (Shaw et al ., 2004).…”

De novo Assembly and Characterization of Patagonian Toothfish Transcriptome and Develop of EST-SSR Markers for Population Genetics

“…Currently, it is widely accepted that the application of genetic knowledge is essential for the conservation and sustainable use of natural resources (Supple and Shapiro, 2018). However, and in contrast with the ecological, evolutionary, and economic importance of this species, the number of studies focused on the evaluation of genetic aspects of Patagonian toothfish are limited and isolated (Smith and McVeagh, 2000;Shaw et al, 2004;Rogers et al, 2006;Toomey et al, 2016;Canales-Aguirre et al, 2018). These studies have used either mitochondrial DNA or a very limited number of microsatellite (simple sequence repeat, SSR) markers.…”

Against all odds: a tale of marine range expansion with maintenance of extremely high genetic diversity

“…The most plausible hypotheses involve: (1) the mutation rate of the fragment, (2) the evolutionary rates hypothesis, or (3) the metabolic rate theory (e.g. 50 ). The mitochondrial control region is a high-mutation region organized in hypervariable regions flanking a central conserved region and is considered the most variant non-coding gene in fishes (e.g.…”