Summary: | The diversification of the teleost suborder Notothenioidei (Perciformes) in Antarctic waters provides one of the most striking examples of a marine adaptive radiation. Along with a number of adaptations to the cold environment, such as the evolution of antifreeze glycoproteins, notothenioids diversified into eight families and at least 130 species. Here, we investigate the genetic population structure of the humped rockcod (Gobionotothen gibberifrons), a benthic notothenioid fish. Six populations were sampled at different locations around the Scotia Sea, comprising a large part of the species’ distribution range (N=165). Our analyses based on mitochondrial DNA sequence data (352 bp) and eight microsatellite markers reveal a lack of genetic structuring over large geographic distances (ΦST≤0.058, F ST≤0.005, p-values nonsignificant). In order to test whether this was due to passive larval dispersal, we used GPS-tracked drifter trajectories, which approximate movement of passive surface particles with ocean currents. The drifter data indicate that the Antarctic Circumpolar Current (ACC) connects the sampling locations in one direction only (West-East), and that passive transport is possible within the four-months larval period of G. gibberifrons. Indeed, when applying the isolation-with-migration model in IMA, strong unidirectional West-East migration rates are detected in the humped rockcod. This leads us to conclude that, in G. gibberifrons, genetic differentiation is prevented by gene flow via larval dispersal with the ACC. Microsatellite data for Gobionotothen gibberifronsData for 9 microsatellite loci for 165 Gobionotothen gibberifrons specimens from six sampling locations (Elephant Island, King George Island, Joinville Island a&b, South Georgia, South Sandwich Islands). The file is in MSA format (MSA=Microsatellite Analyzer: http://i122server.vu-wien.ac.at/MSA/MSA_download.html). Raw microsatellite data was transformed using a beta version of the software tandem ...
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