Data from: Did post-glacial sea-level changes initiate the evolutionary divergence of a Tasmanian endemic raptor from its mainland relative?

Populations on continental islands are often distinguishable from mainland conspecifics with respect to body size, appearance, behaviour, or life history, and this is often congruent with genetic patterns. It is commonly assumed that such differences developed following the complete isolation of populations by sea level rise following the Last Glacial Maximum (LGM). However, population divergence may pre-date the LGM, or marine dispersal and colonisation of islands may have occurred more recently; in both cases, populations may have also diverged despite on-going gene flow. Here we test these alternative hypotheses for the divergence between wedge-tailed eagles from mainland Australia (Aquila audax audax) and the threatened Tasmanian subspecies (A. a. fleayi), based on variation at 20 microsatellite loci and mtDNA. Coalescent analyses indicate that population divergence appreciably post-dates the severance of terrestrial habitat continuity, and occurred without any subsequent gene flow. We infer a recent colonisation of Tasmania by marine dispersal, and cannot discount founder effects as the cause of differences in body size and life history. We call into question the general assumption of post-LGM marine transgression as the initiator of divergence of terrestrial lineages on continental islands and adjacent mainland, and highlight the range of alternative scenarios that should be considered.大陆岛屿种群往往在体型、外形、行为或生活史方面与大陆同种种群存在显著差异，且此类差异通常与遗传模式相契合。学界普遍认为，此类差异产生于末次冰盛期（Last Glacial Maximum, LGM）后海平面上升导致种群完全隔离的情境之下。然而，种群分化可能早于末次冰盛期，亦或是海洋扩散与岛屿定殖事件发生得更晚；在这两种情形下，即便存在持续的基因流，种群仍可能发生分化。本研究基于20个微卫星位点（microsatellite loci）与线粒体DNA（mtDNA）的变异信息，针对澳大利亚大陆楔尾雕（Aquila audax audax）与受威胁的塔斯马尼亚亚种（A. a. fleayi）之间的分化，检验上述两种对立假说。溯祖分析（coalescent analyses）结果显示，种群分化显著晚于陆地生境连续性的断裂，且分化后未发生后续基因流。我们推断，楔尾雕通过海洋扩散新近定殖塔斯马尼亚，且无法排除奠基者效应（founder effects）是导致其体型与生活史差异的原因。本研究对“末次冰盛期后海侵（marine transgression）是引发大陆岛屿及其邻近大陆陆地谱系分化的起始因素”这一普遍假设提出质疑，并强调应考虑更多样的替代情景。