Ehrich D, Stenseth N C
Division of Zoology, Department of Biology, University of Oslo, PO Box 1050, Blindern, N-0316 Oslo, Norway.
Heredity (Edinb). 2001 Jun;86(Pt 6):716-30. doi: 10.1046/j.1365-2540.2001.00883.x.
In a continuous habitat, restricted dispersal and local genetic drift are likely to create a pattern of increasing genetic differentiation with distance. Here, we describe the genetic structure of Siberian lemming (Lemmus sibiricus) populations in a continuous tundra habitat on the western coast of the Taimyr Peninsula, in order to determine the spatial scale at which genetic differentiation and isolation by distance occur. Sampling was carried out at three different geographical scales: (1) a continuous 11 km transect; (2) localities 10-30 km apart; and (3) two localities at 300 and 600 km from the main study area. Two types of genetic markers were used: partial sequences of the mitochondrial DNA control region and four microsatellite loci. On this basis the study populations were genetically quite homogeneous within patches extending over 8 km or more. Contrary to theoretical predictions, no pattern of isolation by distance among patches could be identified. This observation was interpreted as representing populations in migration-drift disequilibrium after a recent major mixing event. The lack of concordance between mtDNA haplotype phylogeny and the geographical distribution of haplotypes supported this interpretation. Spatial autocorrelation among individual genotypes on a local scale was weak and observed only in females, indicating a considerable amount of mostly male-mediated gene flow. Average gene flow per generation was estimated to be in the range of several hundred metres.
在连续的栖息地中，有限的扩散和局部遗传漂变可能会形成一种随着距离增加而遗传分化加剧的模式。在此，我们描述了泰梅尔半岛西海岸连续苔原栖息地中西伯利亚旅鼠（Lemmus sibiricus）种群的遗传结构，以确定遗传分化和距离隔离发生的空间尺度。采样在三个不同的地理尺度上进行：（1）一条连续的11公里样带；（2）相距10 - 30公里的地点；以及（3）距离主要研究区域300公里和600公里的两个地点。使用了两种类型的遗传标记：线粒体DNA控制区的部分序列和四个微卫星位点。在此基础上，在延伸超过8公里或更长的斑块内，研究种群在遗传上相当同质。与理论预测相反，在斑块之间未发现距离隔离模式。这一观察结果被解释为代表了最近一次重大混合事件后处于迁移 - 漂变不平衡状态的种群。线粒体DNA单倍型系统发育与单倍型地理分布之间缺乏一致性支持了这一解释。在局部尺度上个体基因型之间的空间自相关较弱，且仅在雌性中观察到，表明存在大量主要由雄性介导的基因流动。每代的平均基因流动估计在几百米的范围内。
