Data from: Demographic history inferred from genome-wide data reveals two lineages of sheldgeese endemic to a glacial refugium in the southern Atlantic

Aim: The Malvinas/Falkland Islands (MFI) constitute the largest archipelago in the southern Atlantic, and harbour endemic lineages that presumably evolved after sea-level rise associated with glacial periods isolated ancestral populations. We investigate the role of the MFI in isolating populations from continental counterparts of two highly vagile species: the sheldgeese Chloephaga picta and Chloephaga rubidiceps. Location: Patagonia and the Malvinas/Falkland Islands. Methods: We sampled C. picta and C. rubidiceps on the continent and MFI. Using a reduced-representation genomic approach, we quantified the genetic differentiation between insular and continental populations of both species, and used coalescent-based analyses to model their demography. Results: The MFI harbour independently evolving lineages of C. picta and C. rubidiceps, which diverged from their continental counterparts during the Middle-Late Pleistocene and have since experienced negligible gene flow. Main conclusions: The ~450 km that separate the archipelago from the continent are sufficient to isolate populations of these putatively highly vagile species. Ancestral lineages may have reached the MFI refugium during glacial cycles. Without conservation measures, the drastic decline of the morphologically, behaviourally and ecologically distinct continental population of C. rubidiceps, to <1000 individuals, may lead to the extinction of an independently evolving taxon.研究目的：马尔维纳斯群岛/福克兰群岛（Malvinas/Falkland Islands，MFI）是南大西洋规模最大的群岛，其分布有特有演化支，该演化支被认为是在冰川时期海平面上升隔绝祖先种群后演化形成。本研究旨在探究MFI对两种极具漫游能力的雁类——高地草雁（*Chloephaga picta*）和红翅草雁（*Chloephaga rubidiceps*）的大陆种群与群岛种群的隔离作用。 研究区域：巴塔哥尼亚与马尔维纳斯群岛/福克兰群岛。 研究方法：本研究在大陆及MFI采集了高地草雁与红翅草雁的样本，采用简化代表性基因组分析技术，量化了两个物种的岛屿种群与大陆种群间的遗传分化，并运用基于溯祖理论的分析方法对其种群历史动态进行建模。 研究结果：MFI分布有高地草雁与红翅草雁的独立演化支，这两个支系于中更新世晚期至晚更新世时期与其大陆姊妹类群发生分化，此后二者间的基因交流极其有限。 主要结论：分隔该群岛与大陆的约450千米地理距离，足以隔绝这两种被认为具有高度漫游能力的物种种群。祖先演化支可能在冰川周期中抵达该群岛的冰期避难所。若不采取保护措施，红翅草雁大陆种群在形态、行为与生态上均具有独特性，其数量已锐减至不足1000只，这可能导致一个独立演化的类群彻底灭绝。