Taylor Z S, Hoffman S M G
Department of Biology, Miami University, Oxford, OH, USA.
Heredity (Edinb). 2014 Jun;112(6):588-95. doi: 10.1038/hdy.2013.140. Epub 2014 Jan 22.
Dramatic changes in the North American landscape over the last 12 000 years have shaped the genomes of the small mammals, such as the white-footed mouse (Peromyscus leucopus), which currently inhabit the region. However, very recent interactions of populations with each other and the environment are expected to leave the most pronounced signature on rapidly evolving nuclear microsatellite loci. We analyzed landscape characteristics and microsatellite markers of P. leucopus populations along a transect from southern Ohio to northern Michigan, in order to evaluate hypotheses about the spatial distribution of genetic heterogeneity. Genetic diversity increased to the north and was best approximated by a single-variable model based on habitat availability within a 0.5-km radius of trapping sites. Interpopulation differentiation measured by clustering analysis was highly variable and not significantly related to latitude or habitat availability. Interpopulation differentiation measured as FST values and chord distance was correlated with the proportion of habitat intervening, but was best explained by agricultural distance and by latitude. The observed gradients in diversity and interpopulation differentiation were consistent with recent habitat availability being the major constraint on effective population size in this system, and contradicted the predictions of both the postglacial expansion and core-periphery hypotheses.
在过去12000年里，北美地貌的剧烈变化塑造了如今栖息在该地区的小型哺乳动物的基因组，比如白足鼠（白足鼠属）。然而，种群间以及种群与环境间的近期相互作用，预计会在快速进化的核微卫星基因座上留下最为显著的印记。我们分析了从俄亥俄州南部到密歇根州北部一条样带上白足鼠种群的景观特征和微卫星标记，以便评估有关遗传异质性空间分布的假说。遗传多样性向北增加，并且基于诱捕地点半径0.5公里范围内的栖息地可利用性的单变量模型能最好地对其进行近似。通过聚类分析测得的种群间分化高度可变，且与纬度或栖息地可利用性无显著关联。以FST值和弦距衡量的种群间分化与居间栖息地的比例相关，但农业距离和纬度能最好地解释这一现象。观察到的多样性和种群间分化梯度与近期栖息地可利用性是该系统中有效种群大小的主要限制因素这一观点一致，并且与冰期后扩张假说和核心-边缘假说的预测相矛盾。
