Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
Institute of Biology, Leiden University, Leiden, The Netherlands.
Mol Ecol. 2022 Apr;31(7):1951-1962. doi: 10.1111/mec.16230. Epub 2021 Oct 30.
Understanding the impact of historical and demographic processes on genetic variation is essential for devising conservation strategies and predicting responses to climate change. Recolonization after Pleistocene glaciations is expected to leave distinct genetic signatures, characterised by lower genetic diversity in previously glaciated regions. Populations' positions within species ranges also shape genetic variation, following the central-marginal paradigm dictating that peripheral populations are depauperate, sparse and isolated. However, the general applicability of these patterns and relative importance of historical and demographic factors remains unknown. Here, we analysed the distribution of genetic variation in 91 native species of North American plants by coupling microsatellite data and species distribution modelling. We tested the contributions of historical climatic shifts and the central-marginal hypothesis on genetic diversity and structure on the whole data set and across subsets based on taxonomic groups and growth forms. Decreased diversity was found with increased distance from potential glacial refugia, coinciding with the expected make-up of postglacially colonised localities. At the range periphery, lower genetic diversity, higher inbreeding levels and genetic differentiation were reported, following the assumptions of the central-marginal hypothesis. History and demography were found to have approximately equal importance in shaping genetic variation.
了解历史和人口过程对遗传变异的影响对于制定保护策略和预测对气候变化的反应至关重要。更新世冰川消融后的再殖民化预计会留下明显的遗传特征，表现为先前冰川融化地区的遗传多样性较低。按照中央-边缘范式，物种范围内的种群位置也会影响遗传变异，该范式规定，边缘种群资源匮乏、稀疏且孤立。然而，这些模式的普遍适用性以及历史和人口因素的相对重要性仍然未知。在这里，我们通过结合微卫星数据和物种分布模型，分析了 91 种北美本地植物的遗传变异分布。我们在整个数据集和基于分类群和生长形式的子集上测试了历史气候变化和中央-边缘假说对遗传多样性和结构的贡献。与预期的冰川后定居地组成一致，我们发现随着与潜在冰川避难所的距离增加，多样性降低。在范围的边缘，报告了较低的遗传多样性、较高的近交水平和遗传分化，这符合中央-边缘假说的假设。历史和人口因素在塑造遗传变异方面具有大致相同的重要性。
