Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6.
Mol Ecol. 2013 Sep;22(17):4483-98. doi: 10.1111/mec.12411. Epub 2013 Jul 29.
Understanding how gene flow shapes contemporary population structure requires the explicit consideration of landscape composition and configuration. New landscape genetic approaches allow us to link such heterogeneity to gene flow within and among populations. However, the attribution of cause is difficult when landscape features are spatially correlated, or when genetic patterns reflect past events. We use spatial Bayesian clustering and landscape resistance analysis to identify the landscape features that influence gene flow across two regional populations of the eastern massasauga rattlesnake, Sistrurus c. catenatus. Based on spatially explicit simulations, we inferred how habitat distribution modulates gene flow and attempted to disentangle the effects of spatially confounded landscape features. We found genetic clustering across one regional landscape but not the other, and also local differences in the effect of landscape on gene flow. Beyond the effects of isolation-by-distance, water bodies appear to underlie genetic differentiation among individuals in one regional population. Significant effects of roads were additionally detected locally, but these effects are possibly confounded with the signal of water bodies. In contrast, we found no signal of isolation-by-distance or landscape effects on genetic structure in the other regional population. Our simulations imply that these local differences have arisen as a result of differences in population density or tendencies for juvenile rather than adult dispersal. Importantly, our simulations also demonstrate that the ability to detect the consequences of contemporary anthropogenic landscape features (e.g. roads) on gene flow may be compromised when long-standing natural features (e.g. water bodies) co-exist on the landscape.
理解基因流如何塑造当代人口结构，需要明确考虑景观组成和配置。新的景观遗传方法使我们能够将这种异质性与种群内和种群间的基因流联系起来。然而，当景观特征在空间上相互关联，或者遗传模式反映过去的事件时，归因就变得困难了。我们使用空间贝叶斯聚类和景观阻力分析来确定影响东部响尾蛇（Sistrurus c. catenatus）两个区域种群基因流的景观特征。基于空间显式模拟，我们推断了生境分布如何调节基因流，并试图区分空间上混淆的景观特征的影响。我们发现一个区域景观存在遗传聚类，但另一个区域没有，而且景观对基因流的影响也存在局部差异。除了隔离距离的影响外，水体似乎是一个区域种群中个体遗传分化的基础。此外，在局部地区还检测到了道路的显著影响，但这些影响可能与水体的信号相混淆。相比之下，我们在另一个区域种群中没有发现隔离距离或景观对遗传结构的影响信号。我们的模拟表明，这些局部差异是由于种群密度的差异或幼体而非成体扩散的倾向所致。重要的是，我们的模拟还表明，当长期存在的自然特征（如水体）与当代人为景观特征（如道路）共存时，检测当代人为景观特征（如道路）对基因流的影响的能力可能会受到影响。
