Population size and time since island isolation determine genetic diversity loss in insular frog populations

Understanding the factors that contribute to loss of genetic diversity in fragmented populations is crucial for conservation measurements. Land-bridge archipelagoes offer ideal model systems for identifying the long-term effects of these factors on genetic variations in wild populations. In this study, we used 9 microsatellite markers to quantify genetic diversity and differentiation of 810 pond frogs (Pelophylax nigromaculataus) from 24 islands of the Zhoushan Archipelago and 3 sites on nearby mainland China and estimated the effects of the island area, population size, time since island isolation, distance to the mainland and distance to the nearest larger island on reduced genetic diversity of insular populations. The mainland populations displayed higher genetic diversity than insular populations. Genetic differentiations and no obvious gene flow were detected among the frog populations on the islands. Hierarchical partitioning analysis showed that only time since island isolation (...解析破碎化种群中遗传多样性丧失的驱动因素，对于物种保护工作至关重要。陆桥群岛（land-bridge archipelagoes）是探究此类因素对野生种群遗传变异产生长期影响的理想模型系统。本研究采用9个微卫星标记（microsatellite markers），对采自舟山群岛24个岛屿及中国大陆邻近区域3个采样点的810只黑斑侧褶蛙（Pelophylax nigromaculataus）的遗传多样性与遗传分化进行定量分析，并评估了岛屿面积、种群规模、岛屿隔离时长、与大陆的距离以及与最近大岛的距离等因子对岛屿种群遗传多样性降低的影响。研究结果表明，大陆种群的遗传多样性显著高于岛屿种群；岛屿间蛙类种群存在明显遗传分化，且未检测到显著的基因交流。分层分区分析（hierarchical partitioning analysis）结果显示，仅岛屿隔离时长（……