Department of Zoology, Miami University, Oxford, OH 45056, USA.
J Hered. 2012 Jan-Feb;103(1):71-9. doi: 10.1093/jhered/esr100. Epub 2011 Oct 4.
The Great Lakes impose high levels of natural fragmentation on local populations of terrestrial animals in a way rarely found within continental ecosystems. Although separated by major water barriers, woodland deer mouse (Peromyscus maniculatus gracilis) populations on the islands and on the Upper Peninsula (UP) and Lower Peninsula (LP) of Michigan have previously been shown to have a mitochondrial DNA contact zone that is incongruent with the regional landscape. We analyzed 11 microsatellite loci for 16 populations of P. m. gracilis distributed across 2 peninsulas and 6 islands in northern Michigan to address the relative importance of geographical structure and inferred postglacial colonization patterns in determining the nuclear genetic structure of this species. Results showed relatively high levels of genetic structure for this species and a significant correlation between interpopulation differentiation and separation by water but little genetic structure and no isolation-by-distance within each of the 2 peninsulas. Genetic diversity was generally high on both peninsulas but lower and correlated to island size in the Beaver Island Archipelago. These results are consistent with the genetic and demographic isolation of Lower Peninsula populations, which is a matter of concern given the dramatic decline in P. m. gracilis abundance on the Lower Peninsula in recent years.
五大湖以一种在大陆生态系统中很少见的方式对陆地动物的局部种群造成了高度的自然破碎化。尽管被主要的水域障碍隔开，但密歇根州岛屿上和上半岛（UP）和下半岛（LP）的林地鹿鼠（Peromyscus maniculatus gracilis）种群先前已被证明具有线粒体 DNA 接触区，与区域景观不一致。我们分析了分布在密歇根州北部的 2 个半岛和 6 个岛屿上的 16 个 P. m. gracilis 种群的 11 个微卫星位点，以解决地理结构和推断的冰川后殖民化模式在确定该物种的核遗传结构方面的相对重要性。结果表明，该物种的遗传结构水平相对较高，种群间的分化与水体隔离之间存在显著相关性，但在 2 个半岛内的每个半岛内遗传结构和隔离程度都较低。遗传多样性在两个半岛上都很高，但在比弗岛群岛中与岛屿大小相关。这些结果与下半岛种群的遗传和人口隔离一致，考虑到近年来下半岛 P. m. gracilis 数量的急剧下降，这是一个令人担忧的问题。
