Population genetic structure of Lepidonotothen larsenirevisited: Cyband microsatellites suggest limited connectivity in the Southern Ocean

Antarctic fishes (Notothenioidei) are characterized by unusually long pelagic larval stages of up to more than 1 yr, and population genetic studies on notothenioids have often revealed insignificant population differentiations over large geographic scales. Hence, gene flow by passive larval dispersal with ocean currents is often assumed to be predominant among notothenioid populations. We re-examined the genetic population structure of the semi-pelagic painted notothen Lepidonotothen larseni in the Atlantic sector of the Southern Ocean based on cytochrome b gene sequences and microsatellite markers, for which absence of population structure had been inferred in a preliminary study. Our new results suggest restricted gene flow between populations and low levels of successful dispersal with the currents. Hence, long pelagic larval phase durations do not translate into high genetic exchanges. In addition, we provide evidence based on Bayesian skyline plots of increasing population sizes in this sub-Antarctic species since the last glacial maximum.