Phylogeography of postglacial range expansion in Juglans mandshurica (Juglandaceae) reveals no evidence of bottleneck, loss of genetic diversity, or isolation by distance in the leading-edge populations
Phylogeography of postglacial range expansion in Juglans mandshurica (Juglandaceae) reveals no evidence of bottleneck, loss of genetic diversity, or isolation by distance in the leading-edge populations
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核桃科（Juglandaceae）冰期后范围扩张的系统发育地理学显示，没有证据表明前沿种群存在瓶颈、遗传多样性丧失或距离隔离
DOI：
10.1016/j.ympev.2016.06.005
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发表时间：
2016
影响因子：
4.1
通讯作者：
Bai Wei-Ning
中科院分区：
文献类型：
--
作者：
Wang Wen-Ting;Xu Bing;Zhang Da-Yong;Bai Wei-Ning
过去对高纬度地区冰期后再殖民模式的研究表明，扩散能力在温带树木遗传多样性和种群结构的形成中起着重要作用。然而，这些研究大多集中在长距离扩散之后的指数增长的物种上，因此无法揭示逐渐扩张的模式。本文研究了冰期后山林扩展对东北核桃遗传多样性分布的影响。东北核桃是东亚寒温带阔叶林中常见的树种，明显缺乏长距离种子传播能力。利用17个SSR位点对中国东北和朝鲜半岛19个核桃天然居群的遗传多样性和结构进行了分析。利用生态位模型（ENM）方法对当前和过去气候条件下的潜在生境进行了预测。贝叶斯聚类分析揭示了3个类群，这些类群在第四纪多个避难所的多个冰期-间冰期旋回中出现了分化。ENM估计LGM的范围向南移动，但在长白山西部、朝鲜半岛和黄海暴露的海底仍然出现较高的适宜性得分。与同一地区共存的大多数其他冷温带树木相比，东北核桃在冰川后扩张期间没有显示出任何种群瓶颈、遗传多样性丧失或距离隔离的证据。我们的研究清楚地表明，目前的北方种群起源于一个冰川谱系，由于缺乏长距离种子传播机制，通过逐渐推进的前沿重新定居，导致遗传多样性没有纬度上的减少。
The past studies of postglacial recolonization patterns in high latitude regions have revealed a significant role of dispersal capacity in shaping the genetic diversity and population structure of temperate trees. However, most of these studies have focused on species with long-distance dispersal followed by exponential population growth and were therefore unable to reveal the patterns in the case of a gradual expansion. Here we studied the impacts of postglacial range expansions on the distribution of genetic diversity in the Manchurian walnut (Juglans mandshurica), a common tree of East Asian cool-temperate deciduous forests that apparently lacks long-distance seed dispersal ability. The genetic diversity and structure of 19 natural walnut populations in Northeast China and the Korean Peninsula were examined using 17 nuclear simple sequence repeat (SSR) loci. Potential habitats under current and past climatic conditions were predicted using the ecological niche modelling (ENM) method. Bayesian clustering analysis revealed three groups, which were inferred to have diverged through multiple glacial-interglacial cycles in multiple refugia during the Quaternary Period. ENM estimated a southward range shift at the LGM, but high suitability scores still occurred in the western parts of the Changbai Mountains (Northeast China), the Korean peninsula and the exposed seafloor of the Yellow Sea. In contrast to most other cool-temperate trees co-occurring in the same region, the Manchurian walnut did not show any evidence of a population bottleneck, loss of genetic diversity or isolation by distance during the postglacial expansion. Our study clearly indicates that current northern populations originated from one glacial lineage and recolonization via a gradually advancing front due to the lack of a long-distance seed dispersal mechanism led to no latitudinal decrease in genetic diversity.