Hassel Kristian, Såstad Sigurd M, Gunnarsson Urban, Söderström Lars
Museum of Natural History and Archaeology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway;
Am J Bot. 2005 Oct;92(10):1684-90. doi: 10.3732/ajb.92.10.1684.
Genetic variation in the expanding moss species Pogonatum dentatum was studied using intersimple sequence repeat (ISSR) markers. The genetic consequences of range expansion were studied by comparing source populations in a mountain area with populations from a recently colonized lowland area in Sweden. Indices of genetic variation show slightly lower number of alleles per locus in the lowlands and a similar gene diversity in both areas. Three of four lowland populations had evidence of a recently passed bottleneck. Considerably higher haplotype diversity was found in the recently colonized lowlands compared to source populations in the mountains. Patterns of allelic diversity suggest that P. dentatum experiences loss of genetic variation through founder effects and genetic drift when expanding its distribution range. Higher haplotypic diversity, less linkage disequilibrium, and fewer compatible loci indicate that sexual recombination is relatively more important in the lowlands compared to the mountains. A likely explanation is higher success of establishment from spores in the lowlands, while clonal propagation predominates in the mountains. Less genetic differentiation among lowland populations indicates more gene flow in the lowland area, involving more spores and/or fragments moving among populations.
利用简单序列重复区间（ISSR）标记研究了正在扩张的齿叶白发藓（Pogonatum dentatum）物种的遗传变异。通过比较山区的源种群与瑞典最近殖民的低地地区的种群，研究了范围扩张的遗传后果。遗传变异指数显示，低地每个位点的等位基因数量略少，且两个地区的基因多样性相似。四个低地种群中有三个有近期经历瓶颈的证据。与山区的源种群相比，在最近殖民的低地发现了相当高的单倍型多样性。等位基因多样性模式表明，齿叶白发藓在扩大其分布范围时，通过奠基者效应和遗传漂变经历了遗传变异的丧失。更高的单倍型多样性、更少的连锁不平衡和更少的兼容位点表明，与山区相比，有性重组在低地相对更重要。一个可能的解释是，低地孢子建立的成功率更高，而山区以克隆繁殖为主。低地种群之间的遗传分化较小，表明低地地区的基因流动更多，涉及更多在种群间移动的孢子和/或片段。
