Genetic divergence and signatures of natural selection in marginal populations of a keystone, long-lived conifer, eastern white pine (Pinus strobus) from northern Ontario

Marginal populations are expected to provide the frontiers for adaptation, evolution and range shifts of plant species under the anticipated climate change conditions. Marginal populations are predicted to show genetic divergence from central populations due to their isolation, and divergent natural selection and genetic drift operating therein. Marginal populations are also expected to have lower genetic diversity and effective population size (Ne) and higher genetic differentiation than central populations. We tested these hypotheses using eastern white pine (Pinus strobus) as a model for keystone, long-lived widely-distributed plants. All 614 eastern white pine trees, in a complete census of two populations each of marginal old-growth, central old-growth, and central second-growth, were genotyped at 11 microsatellite loci. The central populations had significantly higher allelic and genotypic diversity, latent genetic potential (LGP) and Ne than the marginal populations. However, het...

在预期的气候变化情境下，边缘种群（marginal populations）被认为是植物物种适应、演化及分布范围变迁的前沿研究载体。受地理隔离、定向自然选择与遗传漂变的影响，边缘种群被预测会与中心种群（central populations）产生遗传分化。此外，相较于中心种群，边缘种群预计会具备更低的遗传多样性与有效种群大小（Ne），同时遗传分化程度更高。本研究以北美乔松（Pinus strobus）作为长寿、广布关键植物物种的模式类群，对上述假说开展验证。研究对两类边缘老龄种群、两类中心老龄种群以及两类中心次生种群进行全面普查，共纳入614株北美乔松个体，并对其11个微卫星位点（microsatellite loci）进行基因分型。结果显示，中心种群的等位基因多样性、基因型多样性、潜在遗传潜能（latent genetic potential, LGP）以及有效种群大小均显著高于边缘种群。然而，原文后续内容截断为"het..."