Yu Wenhao, Wu Baofeng, Wang Xinyu, Yao Zhi, Li Yonghua, Liu Yongbo
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 8 Dayangfang, 100012 Beijing, China.
Hortic Res. 2020 Oct 13;7:172. doi: 10.1038/s41438-020-00401-1. eCollection 2020.
Spatial scale partly explains the differentiated effects of habitat fragmentation on plant biodiversity, but the mechanisms remain unclear. To investigate the effects of habitat fragmentation on genetic diversity at different scales, we sampled Planch. at broad and fine scales, China. The broad-scale sampling included five mountain populations and one oceanic island population (Zhoushan Archipelago), and the fine-scale sampling covered 11 lake islands and three neighboring land populations in Thousand-Island Lake (TIL). These populations were genotyped at 30 microsatellite loci, and genetic diversity, gene flow, and genetic differentiation were evaluated. Genetic differentiation was positively related to geographical distance at the broad scale, indicating an isolation-by-distance effect of habitat fragmentation on genetic diversity. The oceanic population differed from the mainland populations and experienced recent bottleneck events, but it showed high gene flow with low genetic differentiation from a mountain population connected by the Yangtze River. At the fine scale, no negative genetic effects of habitat fragmentation were found because seed dispersal with water facilitates gene flow between islands. The population size of was positively correlated with the area of TIL islands, supporting island biogeography theory, but no correlation was found between genetic diversity and island area. Our results highlight the scale-dependent effects of habitat fragmentation on genetic diversity and the importance of connectivity between island-like isolated habitats at both the broad and fine scales.
空间尺度部分解释了栖息地破碎化对植物生物多样性的差异化影响，但其机制仍不清楚。为了研究不同尺度下栖息地破碎化对遗传多样性的影响，我们在中国广泛和精细尺度上对中华水韭进行了采样。广泛尺度的采样包括五个山地种群和一个海洋岛屿种群（舟山群岛），精细尺度的采样涵盖了千岛湖的11个湖心岛和三个相邻陆地种群。对这些种群的30个微卫星位点进行了基因分型，并评估了遗传多样性、基因流和遗传分化。在广泛尺度上，遗传分化与地理距离呈正相关，表明栖息地破碎化对遗传多样性存在距离隔离效应。海洋岛屿种群与大陆种群不同，经历了近期的瓶颈事件，但它与通过长江相连的一个山地种群之间表现出高基因流和低遗传分化。在精细尺度上，未发现栖息地破碎化的负面遗传效应，因为水介导的种子扩散促进了岛屿间的基因流。中华水韭的种群大小与千岛湖岛屿面积呈正相关，支持岛屿生物地理学理论，但未发现遗传多样性与岛屿面积之间存在相关性。我们的研究结果突出了栖息地破碎化对遗传多样性的尺度依赖性影响，以及在广泛和精细尺度上类岛屿孤立栖息地之间连通性的重要性。
