Rapid environmental change is reshaping ecosystems and driving species loss globally. Carnivore populations have declined and retracted rapidly and have been the target of numerous translocation projects. Success, however, is complicated when these efforts occur in novel ecosystems. Identifying refuges, locations that are resistant to environmental change, within a translocation framework should improve population recovery and persistence. American martens (Martes americana) are the most frequently translocated carnivore in North America. As elsewhere, martens were extirpated across much of the Great Lakes region by the 1930s and, despite multiple translocations beginning in the 1950s, martens remain of regional conservation concern. Surprisingly, martens were rediscovered in 2014 on the Apostle Islands of Lake Superior after a putative absence of >40 yr. To identify the source of martens to the islands and understand connectivity of the reintroduction network, we collected genetic data on martens from the archipelago and from all regional reintroduction sites. In total, we genotyped 483 individual martens, 43 of which inhabited the Apostle Islands (densities 0.42–1.46 km⁻²). Coalescent analyses supported the contemporary recolonization of the Apostle Islands with progenitors likely originating from Michigan, which were sourced from Ontario. We also identified movements by a first-order relative between the Apostle Islands and the recovery network. We detected some regional gene flow, but in an unexpected direction: individuals moving from the islands to the mainland. Our findings suggest that the Apostle Islands were naturally recolonized by progeny of translocated individuals and now act as a source back to the reintroduction sites on the mainland. We suggest that the Apostle Islands, given its protection from disturbance, complex forest structure, and reduced carnivore competition, will act as a potential refuge for marten along their trailing range boundary and a central node for regional recovery. Our work reveals that translocations, even those occurring along southern range boundaries, can create recovery networks that function like natural metapopulations. Identifying refuges, locations that are resistant to environmental change, within these recovery networks can further improve species recovery, even within novel environments. Future translocation planning should a priori identify potential refuges and sources to improve short-term recovery and long-term persistence.

中文翻译：

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恢复网络导致群岛的自然重新殖民和潜在的后缘避难所

快速的环境变化正在重塑生态系统并导致全球物种丧失。食肉动物种群迅速减少和收缩，成为众多易地项目的目标。然而，当这些努力发生在新的生态系统中时，成功是复杂的。在易地框架内确定能够抵抗环境变化的避难所和地点，应该可以提高种群的恢复和持久性。美国貂（Martes americana) 是北美最常易位的食肉动物。与其他地方一样，到 1930 年代，五大湖地区的大部分地区都灭绝了貂，尽管在 1950 年代开始多次易地，貂仍然受到区域保护的关注。令人惊讶的是，2014 年在苏必利尔湖的使徒群岛上重新发现了獐子，此前它被假定为缺席了 40 年以上。为了确定岛上貂的来源并了解重新引入网络的连通性，我们收集了来自群岛和所有区域重新引入地点的貂的遗传数据。我们总共对 483 只貂个体进行了基因分型，其中 43 只栖息在使徒群岛（密度 0.42–1.46 km ^-2）。聚结分析支持使徒群岛的当代重新殖民化，其祖先可能来自密歇根州，这些祖先来自安大略省。我们还确定了使徒群岛和恢复网络之间的一阶亲属的运动。我们检测到一些区域基因流动，但方向出乎意料：个体从岛屿迁移到大陆。我们的研究结果表明，使徒群岛自然地被易地个体的后代重新殖民，现在作为回到大陆重新引入地点的来源。我们建议使徒群岛，鉴于其免受干扰、复杂的森林结构和减少的食肉动物竞争，将成为沿其尾随边界的貂的潜在避难所和区域恢复的中心节点。我们的工作表明，易位，即使是发生在南部山脉边界的易位，也可以创建功能类似于自然复合种群的恢复网络。在这些恢复网络中确定能够抵抗环境变化的避难所和位置可以进一步改善物种恢复，即使是在新的环境中也是如此。未来的易地规划应先验确定潜在的避难所和来源，以改善短期恢复和长期持久性。