Data from: Low spatial genetic differentiation associated with rapid recolonization in the New Zealand fur seal Arctocephalus forsteri

Population declines resulting from anthropogenic activities are of major consequence for the long-term survival of species because the resulting loss of genetic diversity can lead to extinction via the effects of inbreeding depression, fixation of deleterious mutations and loss of adaptive potential. Otariid pinnipeds have been exploited commercially to near extinction with some species showing higher demographic resilience and recolonization potential than others. The New Zealand fur seal was heavily impacted by commercial sealing between the late 18th and early 19th centuries, but has recolonized its former range in southern Australia. The species has also recolonized its former range in New Zealand, yet little is known about the pattern of recolonization. Here we first used 11 microsatellite markers (n=383) to investigate the contemporary population structure and dispersal patterns in the New Zealand fur seal (Arctocephalus forsteri). Secondly, we model post-sealing recolonization with one additional mtDNA cytochrome b (n=261) marker. Our data identified three genetic clusters: an Australian, a subantarctic and a New Zealand one, with a weak and probably transient subdivision within the latter cluster. Demographic history scenarios supported a recolonization of the New Zealand coastline from remote west coast colonies, which is consistent with contemporary gene flow and with the species’ high resilience. The present data suggests the management of distinct genetic units in the North and South of New Zealand along a genetic gradient. Assignment of individuals to their colony of origin was limited (32%) with the present data indicating the current microsatellite markers are unlikely sufficient to assign fisheries bycatch of NZ fur seals由人为活动（anthropogenic activities）引发的种群衰退对物种的长期存续至关重要，因为由此造成的遗传多样性丧失，可通过近交衰退（inbreeding depression）、有害突变固定（fixation of deleterious mutations）以及适应潜力（adaptive potential）流失等效应推动物种走向灭绝。海狮科鳍足类（Otariid pinnipeds）曾遭受商业化过度捕捞而濒临灭绝，其中部分类群展现出较其他类群更高的种群恢复力与再定殖潜力。新西兰海狗（Arctocephalus forsteri）在18世纪末至19世纪初的商业海豹捕猎活动中遭受重创，但已重新占据其在澳大利亚南部的原分布范围。该物种同样完成了新西兰境内原分布范围的再定殖，然而学界对其再定殖模式却知之甚少。 本研究首先利用11个微卫星标记（microsatellite markers，n=383），探究了新西兰海狗的当代种群结构与扩散模式；其次，辅以1个线粒体DNA细胞色素b（mtDNA cytochrome b，n=261）标记，对海豹捕猎事件后的种群再定殖过程进行建模分析。研究数据共识别出三个遗传聚类群：分别对应澳大利亚种群、亚南极种群与新西兰种群，其中新西兰种群内部存在微弱且大概率为暂时性的亚结构。种群历史情景分析支持，新西兰海岸线的种群由偏远的西海岸种群再定殖而来，这一结果与当代基因流特征以及该物种较高的恢复力相符。 本研究数据提示，需沿遗传梯度对新西兰南北两侧的不同遗传单元实施差异化管理。利用现有数据对个体进行来源种群归属判定的准确率仅为32%，提示当前的微卫星标记或不足以用于新西兰海狗渔业兼捕个体的来源判定。