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.

岛屿特有种因分布受限且种群隔离，往往演化出独特的遗传与表型多样性，这类多样性对保护管理机构而言具有重要的保护价值。然而这类隔离种群，尤其是那些具有敏感生活史特征的物种，极易受到遗传漂变以及外来野生动物造成的生境退化所带来的负面影响。本研究以加州圣克莱门特岛（San Clemente Island）上的经典“岛屿巨型种”——河氏异鳞蜥（Xantusia riversiana，俗称岛夜蜥（Island Night Lizard））为研究对象，探究其在野化山羊被根除后的种群遗传多样性、遗传结构与种群稳定性。本研究利用DNA微卫星标记进行分析，结果显示：尽管该种群曾经历过放牧活动，但其整体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无显著差异，与生境类型及其退化程度无关。但研究同时发现，与大陆同属物种相比，该种群存在显著的位点特异性遗传变异格局，且遗传多样性水平偏低，因此作为岛屿特有种仍需持续开展针对性保护管理。本研究不仅明确了可作为遗传多样性重要储存库的高海拔与低海拔区域，同时可为未来应对气候变化的其他低扩散能力沿岸生物类群提供参考案例。