Department of Environmental Sciences, ETH Zurich, Universitaetstrasse 16, Zurich, Switzerland.
Mol Ecol. 2011 Feb;20(3):473-85. doi: 10.1111/j.1365-294X.2010.04972.x. Epub 2010 Dec 24.
One of the greatest threats to the long-term viability of migrating plant species is the loss of genetic diversity due to founder effects. Populations can expand as a response to climate change, but it is uncertain if long-lived plant species can maintain sufficient genetic diversity at the leading edge of migrating populations. This study uses an expanding Larix decidua population investigated along a chronosequence at landscape (350 ha) and local (0.8 ha) scales to test whether accelerated migration as a result of climate warming has the potential to intensify genetic erosion. Nine SSR markers revealed similar genetic diversity among eight sub-populations along the chronosequence (overall H(e) = 0.73; SE=0.04). Sub-populations were not genetically differentiated and all sampled individuals (N=730) formed one major genetic cluster indicating homogenizing gene flow despite spatial genetic structure (SGS) up to 80 m. At the local scale, individuals at the leading edge [early successional sub-population (ESSP), N =140] and a sub-population at equilibrium [late successional sub-population (LSSP), N = 290] revealed high genetic diversity in largest-sized cohorts. SGS among juveniles occurred up to 30 m in LSSP but there was no structure in ESSP. Accordingly, a maximum likelihood paternity assignment revealed local gene dispersal in LSSP (2-48 m) and intermediate-to-long distance dispersal into ESSP (115-3132 m). The findings indicate intensive mixing of the genes in this expanding population instead of founder effects and support the view that genetic diversity can be maintained in a long-lived species during rapid population expansion driven by climate warming.
对迁移植物物种长期生存能力的最大威胁之一是遗传多样性的丧失，这是由于奠基者效应造成的。种群可以随着气候变化而扩张，但不确定长寿植物物种是否能够在迁移种群的前沿维持足够的遗传多样性。本研究使用落叶松正在扩张的种群，在景观（350 公顷）和局部（0.8 公顷）尺度上沿着时间序列进行调查，以测试气候变暖导致的加速迁移是否有可能加剧遗传侵蚀。9 个 SSR 标记物在时间序列上的 8 个亚种群中揭示了相似的遗传多样性（总体 H(e) = 0.73；SE = 0.04）。亚种群之间没有遗传分化，所有采样个体（N=730）形成一个主要的遗传聚类，表明尽管存在空间遗传结构（SGS），最大可达 80 m，但仍存在同质化的基因流。在局部尺度上，处于前沿的个体[早期演替亚种群（ESSP），N=140]和处于平衡的亚种群[晚期演替亚种群（LSSP），N=290]在最大规模的队列中表现出较高的遗传多样性。在 LSSP 中，幼树之间的 SGS 最大可达 30 m，但 ESSP 中没有结构。因此，最大似然父本分配显示在 LSSP 中有局部基因扩散（2-48 m）和中等至长距离扩散到 ESSP（115-3132 m）。研究结果表明，在这种不断扩张的种群中，基因的混合程度很高，而不是奠基者效应，并支持遗传多样性在长寿物种中可以在气候变暖驱动的快速种群扩张过程中得到维持的观点。
