Corrigan L J, Fabiani A, Chauke L F, McMahon C R, de Bruyn M, Bester M N, Bastos A, Campagna C, Muelbert M M C, Hoelzel A R
School of Biological and Biomedical Sciences, Durham University, Durham, UK.
Dipartimento di Biologia, Università degli Studi di Roma Tor Vergata, Roma, Italy.
J Evol Biol. 2016 Sep;29(9):1667-79. doi: 10.1111/jeb.12870. Epub 2016 Jun 7.
Understanding observed patterns of connectivity requires an understanding of the evolutionary processes that determine genetic structure among populations, with the most common models being associated with isolation by distance, allopatry or vicariance. Pinnipeds are annual breeders with the capacity for extensive range overlap during seasonal migrations, establishing the potential for the evolution of isolation by distance. Here, we assess the pattern of differentiation among six breeding colonies of the southern elephant seal, Mirounga leonina, based on mtDNA and 15 neutral microsatellite DNA markers, and consider measures of their demography and connectivity. We show that all breeding colonies are genetically divergent and that connectivity in this highly mobile pinniped is not strongly associated with geographic distance, but more likely linked to Holocene climate change and demographic processes. Estimates of divergence times between populations were all after the last glacial maximum, and there was evidence for directional migration in a clockwise pattern (with the prevailing current) around the Antarctic. We discuss the mechanisms by which climate change may have contributed to the contemporary genetic structure of southern elephant seal populations and the broader implications.
要理解观察到的连通性模式，需要了解决定种群间遗传结构的进化过程，最常见的模型与距离隔离、异域性或地理隔离有关。鳍足类动物是一年生繁殖者，在季节性迁徙期间有广泛的活动范围重叠，这为距离隔离的进化创造了条件。在这里，我们基于线粒体DNA和15个中性微卫星DNA标记，评估了南象海豹（Mirounga leonina）六个繁殖群体之间的分化模式，并考虑了它们的种群统计学和连通性指标。我们发现，所有繁殖群体在基因上都是有差异的，而且这种高度移动的鳍足类动物的连通性与地理距离没有很强的关联，而更可能与全新世气候变化和种群统计学过程有关。种群间分化时间的估计都在末次盛冰期之后，并且有证据表明存在围绕南极以顺时针方向（与主流方向一致）的定向迁移。我们讨论了气候变化可能导致南象海豹种群当代遗传结构的机制以及更广泛的影响。
