Schweiger O, Frenzel M, Durka W
UFZ--Centre for Environmental Research Leipzig-Halle, Department of Community Ecology, Theodor-Lieser-Strasse 4, D-06120, Halle, Germany.
Mol Ecol. 2004 Dec;13(12):3645-55. doi: 10.1111/j.1365-294X.2004.02357.x.
Habitat fragmentation is a major force affecting demography and genetic structure of wild populations, especially in agricultural landscapes. The land snail Cepaea nemoralis (L.) was selected to investigate the impact of habitat fragmentation on the spatial genetic structure of an organism with limited dispersal ability. Genetic and morphological patterns were investigated at a local scale of a 500 m transect and a mesoscale of 4 x 4 km in a fragmented agricultural landscape while accounting for variation in the landscape using least-cost models. Analysis of microsatellite loci using expected heterozygosity (HE), pairwise genetic distance (FST/1-FST) and spatial autocorrelograms (Moran's I) as well as shell characteristics revealed spatial structuring at both scales and provided evidence for a metapopulation structure. Genetic diversity was related to morphological diversity regardless of landscape properties. This pointed to bottlenecks caused by founder effects after (re)colonization. Our study suggests that metapopulation structure depended on both landscape features and the shape of the dispersal function. A range of genetic spatial autocorrelation up to 80 m at the local scale and up to 800 m at the mesoscale indicated leptokurtic dispersal patterns. The metapopulation dynamics of C. nemoralis resulted in a patchwork of interconnected, spatially structured subpopulations. They were shaped by gene flow which was affected by landscape features, the dispersal function and an increasing role of genetic drift with distance.
栖息地破碎化是影响野生种群人口统计学和遗传结构的主要因素，在农业景观中尤为如此。选择陆地蜗牛玛瑙螺（Cepaea nemoralis (L.)）来研究栖息地破碎化对具有有限扩散能力的生物体空间遗传结构的影响。在一个破碎化的农业景观中，在500米样带的局部尺度和4×4千米的中尺度上研究了遗传和形态模式，同时使用成本最低模型来考虑景观变化。利用期望杂合度（HE）、成对遗传距离（FST/1 - FST）和空间自相关图（莫兰指数I）对微卫星位点进行分析，以及对壳特征的分析，揭示了两个尺度上的空间结构，并为集合种群结构提供了证据。无论景观特性如何，遗传多样性都与形态多样性相关。这表明（重新）定殖后由奠基者效应导致的瓶颈。我们的研究表明，集合种群结构既取决于景观特征，也取决于扩散函数的形状。在局部尺度上高达80米、在中尺度上高达800米的一系列遗传空间自相关表明了尖峰态扩散模式。玛瑙螺的集合种群动态导致了相互连接、空间结构化的亚种群拼凑分布。它们是由基因流塑造的，而基因流受到景观特征、扩散函数以及遗传漂变随距离增加的作用的影响。
