Concordant genetic breaks, identified by combining clustering and tessellation methods, in two co-distributed alpine plant species

Natural genetic breaks may indicate limitations to gene flow or the presence of contact zones of previously isolated populations. Molecular evidence suggests that genetic breaks have aggregated in distinct geographical areas. We propose a new application of well-established statistical methods for analyzing multilocus genetic data in order to identify intraspecific genetic breaks. The methodological approach combines Bayesian clustering with a spatially explicit maximum-difference algorithm to visualize and quantify breaks between clusters. We used AFLP data of two co-distributed, silicicolous alpine plant species, Geum montanum and G. reptans, exhaustively sampled on a consistent, regular grid over their entire range of the European Alps and the Carpathians. We found a distinct and highly similar allocation of genetic breaks in both species. The pattern of breaks did not conform to scenarios of glacial refugial survival, alternatively in peripheral refugia or on nunataks, as expected d...自然遗传断裂（natural genetic breaks）可能预示着基因流存在限制，或是此前隔离种群的接触带已然形成。分子生物学证据表明，遗传断裂集中分布于特定地理区域内。本研究提出一种基于久经验证的统计方法的全新应用框架，用于分析多位点遗传数据以识别种内遗传断裂。该方法将贝叶斯聚类（Bayesian clustering）与空间显式最大差异算法相结合，可对聚类间的遗传断裂进行可视化展示与量化分析。本研究使用了两种同域分布、适生于硅质基质的高山植物物种——高山水杨梅（Geum montanum）与匍匐水杨梅（G. reptans）的扩增片段长度多态性（AFLP）数据；二者在欧洲阿尔卑斯山与喀尔巴阡山脉的整个分布区内，均通过统一规整的网格开展了全覆盖采样。研究发现，两个物种的遗传断裂分布格局均十分显著且高度相似。该断裂分布模式并不符合我们此前预期的冰期避难所存续场景——无论是外围避难所还是冰原岛峰（nunataks）场景，如预期的d...