Data from: Archipelagic genetics in a widespread Caribbean anole

Aim We examine the influence of fluctuating sea levels in a land-bridge archipelago on the apportioning of intraspecific genetic diversity and divergence in the widespread Puerto Rican crested anole (Anolis cristatellus). We compare three alternative scenarios for genetic diversification in an archipelagic species that contrast the relative influences of periodic isolation versus island connectedness driven by fluctuating sea levels. Our approach combines information from geography and population genetics to assess the influence of island size, island isolation, island historical geography, and population genetic processes such as drift on the contemporary distribution of genetic variation within and among islands. Location The Puerto Rico Bank in the Caribbean focusing primarily on the Spanish, British and U.S. Virgin Islands. Methods We used nuclear and mitochondrial DNA sequences and microsatellite genotypes sampled from A. cristatellus populations to investigate: 1) the broad-scale pattern of phylogeographic divergence across Puerto Rico Bank islands; and 2) diversification within the Virgin Islands archipelago. For the first component, we used sequence data to reconstruct the relationships among 542 samples from across the species’ range. For the second component, we examined the relative influences of island size, isolation, and population genetic processes on the distribution of genetic diversity across the Virgin Islands. Results In the Virgin Islands, A. cristatellus is represented by a monophyletic clade except on the island of Vieques, where two divergent clades coexist. We found evidence for non-equilibrium dynamics in the Virgin Islands, suggesting spatial population expansion during intraglacial periods of low sea level. Main conclusions We found limited evidence that periods of island isolation affected patterns of genetic diversity and differentiation. Instead, we found that the patterns of genetic diversity and divergence in A. cristatellus in the Virgin Islands archipelago are likely shaped by long-term persistence in the region and periods of population spatial expansion.研究目的 本研究旨在探讨陆桥群岛（land-bridge archipelago）的海平面波动，对广布种波多黎各冠安乐蜥（Anolis cristatellus）的种内遗传多样性（intraspecific genetic diversity）分配格局与遗传分化（genetic divergence）的影响。我们对比了群岛物种种内遗传分化的三类备选情景，以辨析海平面波动驱动的周期性岛屿隔离与岛屿连通性的相对影响。本研究结合地理学与种群遗传学信息，评估岛屿面积、岛屿隔离程度、岛屿历史地理，以及遗传漂变等种群遗传过程，对岛屿内外当代遗传变异分布的影响。 研究区域 加勒比海波多黎各陆架，研究重点主要集中于西班牙维尔京群岛、英国维尔京群岛以及美属维尔京群岛。 研究方法 我们利用采自A. cristatellus种群的核DNA、线粒体DNA序列以及微卫星基因型（microsatellite genotypes），开展两项研究：其一，解析波多黎各陆架各岛屿的大尺度系统地理分化（phylogeographic divergence）格局；其二，探究维尔京群岛内的物种分化过程。针对第一项研究内容，我们通过序列数据重建了该物种分布范围内542份样本的系统发育关系。针对第二项研究内容，我们分析了岛屿面积、隔离程度以及种群遗传过程，对维尔京群岛内遗传多样性分布的相对影响。 研究结果 在维尔京群岛中，除别克斯岛存在两个分化支系共存外，A. cristatellus均属于单系支（monophyletic clade）。我们在维尔京群岛种群中检测到非平衡动态（non-equilibrium dynamics）的证据，表明在冰期内海平面较低的时段，该物种种群发生了空间扩张。 主要结论 本研究仅发现有限证据支持岛屿隔离时期对遗传多样性与分化格局的影响。相反，维尔京群岛冠安乐蜥的遗传多样性与分化格局，更可能受该区域的长期种群存续以及阶段性种群空间扩张所塑造。