Genetic and morphological differentiation in Populus nigra L.: isolation by colonization or isolation by adaptation?
Genetic and morphological differentiation in Populus nigra L.: isolation by colonization or isolation by adaptation?
复制标题
尼格拉河群中的遗传和形态学分化：通过适应而隔离或隔离来隔离？
DOI：
10.1111/mec.13192
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发表时间：
2015-06
影响因子：
4.9
通讯作者：
Taylor G
中科院分区：
文献类型：
--
作者：
DeWoody J;Trewin H;Taylor G
确定种群间遗传和形态差异背后的过程是进化生物学的一个核心问题。森林树木通常含有高水平的中性遗传变异，遗传差异通常与种群之间的地理距离有关[距离隔离（IBD）]或由于历史差异事件[殖民化隔离（IBC）]。相反，形态差异很大程度上是由于局部适应。在这里，我们研究了欧洲黑杨杨（Populus nigra L.）的遗传（微卫星）和形态（来自一个普通花园实验）变异，这些黑杨树采集自西欧的13个地点，生长在比利时的一个普通花园中。观察到显著的遗传分化，来自法国的种群比独特的西班牙和中欧基因库表现出更大的混合，与先前描述的冰川避难所（IBC）一致。许多数量性状呈双峰型分布，大致对应于小叶生态型和大叶生态型。对9个气候变量的研究表明，采样地点具有不同的气候，尽管形态和气候差异之间存在显著的相关性，但这种模式并不符合严格的局部适应。基于多变量汇总统计的部分Mantel测试发现，在小叶和大叶生态型的比较中，以及在小叶样本中，但在大叶生态型中，存在显著的残差相关性，这表明小叶形态型中的变异尤其可能是适应性的。一些小叶种群所经历的气候与大叶种群所经历的气候非常相似。我们认为，适应性分化和持续性IBC共同作用产生了黑桫椤的遗传和形态模式。
Identifying processes underlying the genetic and morphological differences among populations is a central question of evolutionary biology. Forest trees typically contain high levels of neutral genetic variation, and genetic differences are often correlated with geographic distance between populations [isolation by distance (IBD)] or are due to historic vicariance events [isolation by colonization (IBC)]. In contrast, morphological differences are largely due to local adaptation. Here, we examined genetic (microsatellite) and morphological (from a common garden experiment) variation in Populus nigra L., European black poplar, collected from 13 sites across western Europe and grown in a common garden in Belgium. Significant genetic differentiation was observed, with populations from France displaying greater admixture than the distinct Spanish and central European gene pools, consistent with previously described glacial refugia (IBC). Many quantitative traits displayed a bimodal distribution, approximately corresponding to small-leaf and large-leaf ecotypes. Examination of nine climatic variables revealed the sampling locations to have diverse climates, and although the correlation between morphological and climatic differences was significant, the pattern was not consistent with strict local adaptation. Partial Mantel tests based on multivariate summary statistics identified significant residual correlation in comparisons of small-leaf to large-leaf ecotypes, and within the small-leaf samples, but not within large-leaf ecotypes, indicating that variation within the small-leaf morphotype in particular may be adaptive. Some small-leaf populations experience climates very similar to those in large-leaf sites. We conclude that adaptive differentiation and persistent IBC acted in combination to produce the genetic and morphological patterns observed in P. nigra.