Muñoz-Pajares A J, García C, Abdelaziz M, Bosch J, Perfectti F, Gómez J M
Plant Biology, CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal.
Departamento de Genética, Universidad de Granada, Granada, Spain.
Mol Ecol. 2017 Mar;26(6):1576-1585. doi: 10.1111/mec.13971. Epub 2017 Jan 27.
The isolation-by-distance model (IBD) predicts that genetic differentiation among populations increases with geographic distance. Yet, empirical studies show that a variety of ecological, topographic and historical factors may override the effect of geographic distance on genetic variation. This may particularly apply to species with narrow but highly heterogeneous distribution ranges, such as those occurring along elevational gradients. Using nine SSR markers, we study the genetic differentiation of the montane pollination-generalist herb, Erysimum mediohispanicum. Because the effects of any given factor may depend on the geographic scale considered, we investigate the contribution of different environmental and historical factors at three different spatial scales. We evaluate five competing models that put forward the role of geographic distance, local environmental factors [biotic interactions (IBEb) and climatic variables (IBEa)], landscape resistance (IBR) and phylogeographic patterns (IBP), respectively. We find significant IBD regardless of the spatial scale and the genetic distance estimator considered. However, IBEa and IBP also play a prominent role in shaping genetic differentiation patterns at the larger spatial scales, and IBR is significant at the fine spatial scale. Overall, our results highlight the importance of combining different estimators, statistical approaches and spatial scales to disentangle the relative importance of the various ecological factors contributing to the shaping of genetic divergence patterns in natural populations.
距离隔离模型（IBD）预测，种群间的遗传分化会随着地理距离的增加而增大。然而，实证研究表明，各种生态、地形和历史因素可能会掩盖地理距离对遗传变异的影响。这在分布范围狭窄但高度异质的物种中可能尤为适用，比如那些沿着海拔梯度分布的物种。我们使用九个简单序列重复（SSR）标记，研究了山地传粉广适性草本植物西班牙中穗香芥（Erysimum mediohispanicum）的遗传分化。由于任何给定因素的影响可能取决于所考虑的地理尺度，我们在三个不同的空间尺度上研究了不同环境和历史因素的作用。我们评估了五个相互竞争的模型，它们分别提出了地理距离、当地环境因素[生物相互作用（IBEb）和气候变量（IBEa）]、景观抗性（IBR）和系统发育地理模式（IBP）的作用。无论考虑何种空间尺度和遗传距离估计方法，我们都发现了显著的距离隔离现象。然而，IBEa和IBP在较大空间尺度上对遗传分化模式的形成也起着重要作用，而IBR在精细空间尺度上具有显著意义。总体而言，我们的结果强调了结合不同估计方法、统计方法和空间尺度以厘清各种生态因素对自然种群遗传分化模式形成的相对重要性的重要性。
