Data from: Historical environment is reflected in modern population genetics and biogeography of an island endemic lizard (Xantusia riversiana reticulata)

The restricted distribution and isolation of island endemics often produces unique genetic and phenotypic diversity of conservation interest to management agencies. However, these isolated species, especially those with sensitive life history traits, are at high risk for the adverse effects of genetic drift and habitat degradation by non-native wildlife. Here, we study the population genetic diversity, structure, and stability of a classic “island giant” (Xantusia riversiana, the Island Night Lizard) on San Clemente Island, California following the removal of feral goats. Using DNA microsatellites, we found that this population is reasonably genetically robust despite historical grazing, with similar effective population sizes and genetic diversity metrics across all sampling locations irrespective of habitat type and degree of degradation. However, we also found strong site-specific patterns of genetic variation and low genetic diversity compared to mainland congeners, warranting continued special management as an island endemic. We identify both high and low elevation areas that remain valuable repositories of genetic diversity and provide a case study for other low-dispersal coastal organisms in the face of future climate change.

岛屿特有种的分布范围受限且彼此隔离，往往会孕育出受管理机构关注、具备保护价值的独特遗传与表型多样性。然而这类孤立物种，尤其是生活史特征较为敏感的类群，极易遭受遗传漂变与外来野生动物造成的生境退化所带来的负面影响。本研究以加利福尼亚州圣克莱门特岛（San Clemente Island）上的经典“岛屿巨型种”——岛夜蜥（Xantusia riversiana）为研究对象，探究其在野化山羊被清除后的种群遗传多样性、种群结构与种群稳定性。通过DNA微卫星（DNA microsatellites）分析，我们发现尽管曾经历历史放牧活动，该种群的遗传稳健性仍较为可观；所有采样点位的有效种群规模与遗传多样性指标均较为相近，不受生境类型与退化程度的影响。但相较于大陆同属物种，本研究也观测到了显著的位点特异性遗传变异模式与较低的遗传多样性，这表明该岛屿特有种仍需持续开展专项保护管理。本研究明确了遗传多样性仍具较高保存价值的高海拔与低海拔区域，并为未来面临气候变化的低扩散能力海岸生物提供了典型研究案例。