Data from: Population differentiation in the context of Holocene climate change for a migratory marine species, the southern elephant seal

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.

要解析观测到的种群连通模式，需先阐明决定种群间遗传结构的进化过程，其中最常见的模型包括距离隔离（isolation by distance）、异域分化（allopatry）以及地理歧化（vicariance）。鳍足类（Pinnipeds）为年度繁殖类群，在季节性迁徙期间可实现大范围分布重叠，这为距离隔离的演化提供了潜在条件。本研究基于线粒体DNA（mtDNA）与15个中性微卫星DNA标记，对南象海豹（Mirounga leonina）的6个繁殖种群的分化模式进行评估，并分析其种群统计特征与连通性相关指标。研究结果显示，所有繁殖种群均存在遗传分化；这种具有高度移动性的鳍足类的种群连通性并未与地理距离呈现显著关联，反而更可能与全新世气候变化及种群动态过程相关。种群间的分化时间估算结果均晚于末次盛冰期（Last Glacial Maximum），且存在证据表明，围绕南极大陆的迁徙呈现顺时针方向（与沿岸主流流向一致）的定向模式。本研究还探讨了气候变化塑造南象海豹种群当代遗传结构的潜在机制，以及该研究的更广泛学术意义。