Coster Stephanie S, Babbitt Kimberly J, Cooper Andrew, Kovach Adrienne I
Department of Natural Resources and the Environment, University of New Hampshire, 114 James Hall, Durham, NH, 03824, USA.
Mol Ecol. 2015 Feb;24(4):742-58. doi: 10.1111/mec.13062. Epub 2015 Feb 2.
Dispersal and gene flow within animal populations are influenced by the composition and configuration of the landscape. In this study, we evaluated hypotheses about the impact of natural and anthropogenic factors on genetic differentiation in two amphibian species, the spotted salamander (Ambystoma maculatum) and the wood frog (Lithobates sylvaticus) in a commercial forest in central Maine. We conducted this analysis at two scales: a local level, focused on factors measured at each breeding pond, and a landscape level, focused on factors measured between ponds. We investigated the effects of a number of environmental factors in six categories including Productivity, Physical, Land Composition, Land Configuration, Isolation and Location. Embryos were sampled from 56 spotted salamander breeding ponds and 39 wood frog breeding ponds. We used a hierarchical Bayesian approach in the program GESTE at each breeding pond and a random forest algorithm in conjunction with a network analysis between the ponds. We found overall high genetic connectivity across distances up to 17 km for both species and a limited effect of natural and anthropogenic factors on gene flow. We found the null models best explained patterns of genetic differentiation at a local level and found several factors at the landscape level that weakly influenced gene flow. This research indicates multiscale investigations that incorporate local and landscape factors are valuable for understanding patterns of gene flow. Our findings suggest that dispersal rates in this system are high enough to minimize genetic structuring and that current forestry practices do not significantly impede dispersal.
动物种群内部的扩散和基因流动受景观的组成和格局影响。在本研究中，我们评估了关于自然和人为因素对缅因州中部一片商品林中两种两栖动物——斑点钝口螈（Ambystoma maculatum）和林蛙（Lithobates sylvaticus）遗传分化影响的假说。我们在两个尺度上进行了分析：局部尺度，关注每个繁殖池塘所测量的因素；景观尺度，关注池塘之间所测量的因素。我们研究了包括生产力、物理因素、土地组成、土地格局、隔离和位置在内的六类环境因素的影响。从56个斑点钝口螈繁殖池塘和39个林蛙繁殖池塘采集了胚胎样本。我们在每个繁殖池塘使用程序GESTE中的层次贝叶斯方法，并结合池塘之间的网络分析使用随机森林算法。我们发现，两种物种在长达17公里的距离上总体具有较高的遗传连通性，自然和人为因素对基因流动的影响有限。我们发现零模型最能解释局部尺度上的遗传分化模式，并在景观尺度上发现了几个对基因流动影响较弱的因素。这项研究表明，纳入局部和景观因素的多尺度调查对于理解基因流动模式很有价值。我们的研究结果表明，该系统中的扩散率足够高，可将遗传结构最小化，并且当前的林业实践不会显著阻碍扩散。
