Purrenhage J L, Niewiarowski P H, Moore F B-G
Department of Biology, University of Akron, Akron, OH 44325, USA.
Mol Ecol. 2009 Jan;18(2):235-47. doi: 10.1111/j.1365-294X.2008.04024.x.
Understanding the impacts of landscape-level processes on the population biology of amphibians is critical, especially for species inhabiting anthropogenically modified landscapes. Many pond-breeding amphibians are presumed to exist as metapopulations, but few studies demonstrate the extent and consequences of this metapopulation structure. Gene flow measures may facilitate the construction of more realistic models of population structure than direct measures of migration. This is especially true for species that are cryptic, such as many amphibians. We used eight polymorphic microsatellite loci to determine the genetic population structure of spotted salamanders (Ambystoma maculatum) breeding at 17 ponds in northeastern Ohio, a landscape fragmented by roads, agriculture, urban areas and the Cuyahoga River. Using a variety of analyses (Bayesian clustering, F-statistics, AMOVA) we generated a model of salamander population genetic structure. Our data revealed patterns of genetic connectivity that were not predicted by geographical distances between ponds (no isolation by distance). We also tested for a relationship between population structure and several indices of landscape resistance, but found no effect of potential barriers to dispersal on genetic connectivity. Strong overall connectivity among ponds, despite the hostile habitat matrix, may be facilitated by a network of riparian corridors associated with the Cuyahoga River; however, high gene flow in this system may indicate a general ability to disperse and colonize beyond particular corridors.
了解景观层面的过程对两栖动物种群生物学的影响至关重要，特别是对于栖息在人为改造景观中的物种。许多在池塘繁殖的两栖动物被认为是以集合种群的形式存在，但很少有研究证明这种集合种群结构的程度和后果。与直接测量迁移相比，基因流测量可能有助于构建更现实的种群结构模型。对于许多两栖动物等隐秘物种来说尤其如此。我们使用了八个多态微卫星位点来确定在俄亥俄州东北部17个池塘繁殖的斑点钝口螈（Ambystoma maculatum）的遗传种群结构，该地区的景观因道路、农业、城市地区和凯霍加河而破碎化。通过各种分析（贝叶斯聚类、F统计量、方差分析），我们生成了一个钝口螈种群遗传结构模型。我们的数据揭示了遗传连通性模式，这些模式并非由池塘之间的地理距离所预测（不存在距离隔离）。我们还测试了种群结构与几种景观抗性指数之间的关系，但发现潜在的扩散障碍对遗传连通性没有影响。尽管栖息地矩阵不利，但池塘之间总体上具有很强的连通性，这可能得益于与凯霍加河相关的河岸走廊网络；然而，这个系统中的高基因流可能表明其具有超越特定走廊进行扩散和殖民的一般能力。
