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的海平面波动对广布物种波多黎各冠安乐蜥（Anolis cristatellus）的种内遗传多样性分配格局与种群分化的影响。我们对比了群岛物种种群遗传分化的三种备选情景，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作用强度。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、岛屿历史地理格局，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格局的影响。
研究区域：加勒比海波多黎各海台，主要聚焦于西班牙、英国及美属维尔京群岛。
研究方法：我们利用采集自波多黎各冠安乐蜥种群的核DNA序列、线粒体DNA序列及微卫星基因型，开展两项研究：1）解析波多黎各海台各岛屿的大尺度系统地理分化格局；2）探究维尔京群岛内的种群分化过程。针对第一项内容，我们利用序列数据重构了该物种分布范围内542份样本的系统发育关系。针对第二项内容，我们分析了岛屿面积、隔离程度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强度。
研究结果：在维尔京群岛中，波多黎各冠安乐蜥构成一个单系演化支，仅在别克斯岛（Vieques）存在两个分化演化支共存的现象。我们在维尔京群岛种群中检测到非平衡种群动态的证据，表明在冰期内低海平面时段，该物种种群曾发生空间扩张。
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产生影响。相反，维尔京群岛冠安乐蜥的遗传多样性与分化格局，更可能受该区域长期种群存续及周期性种群空间扩张过程塑造。