Jacquemyn Hans, Brys Rein, Vandepitte Katrien, Honnay Olivier, Roldán-Ruiz Isabel
Division Forest, Nature and Landscape Research, Catholic University of Leuven, Celestijnenlaan 200E, B-3001 Leuven, Belgium.
Mol Ecol. 2006 Sep;15(10):2801-8. doi: 10.1111/j.1365-294X.2006.02978.x.
In natural plant populations, fine-scale spatial genetic structure can result from limited gene flow, selection pressures or historical events, but the role of each factor is in general hard to discern. One way to investigate the origination of spatial genetic structure within a plant population consists of comparing spatial genetic structure among different life history stages. In this study, spatial genetic structure of the food-deceptive orchid Orchis purpurea was determined across life history stages in two populations that were regenerating after many years of population decline. Based on demographic analyses (2001-2004), we distinguished between recruits and adult plants. For both sites, there was no difference in the proportion of polymorphic loci and expected heterozygosity between life history stages. However, spatial autocorrelation analyses showed that spatial genetic structure increased in magnitude with life history stage. Weak or no spatial genetic structure was observed for recruits, whereas adult plants showed a pattern that is consistent with that found in other species with a predominantly outcrossing mating system. The observed differences between seedlings and adults are probably a consequence of changes in management of the two study sites and associated demographic changes in both populations. Our results illustrate that recurrent population crashes and recovery may strongly affect genetic diversity and fine-scale spatial genetic structure of plant populations.
在自然植物种群中，精细尺度的空间遗传结构可能源于有限的基因流动、选择压力或历史事件，但通常很难辨别每个因素所起的作用。研究植物种群内空间遗传结构起源的一种方法是比较不同生活史阶段的空间遗传结构。在本研究中，我们确定了食物欺骗性兰花紫花红门兰在两个经历多年种群数量下降后正在恢复的种群中不同生活史阶段的空间遗传结构。基于种群统计学分析（2001 - 2004年），我们区分了幼苗和成年植株。对于两个研究地点，生活史阶段之间的多态位点比例和期望杂合度均无差异。然而，空间自相关分析表明，空间遗传结构的强度随生活史阶段增加。在幼苗中观察到较弱或不存在空间遗传结构，而成年植株呈现出与其他主要为异交交配系统的物种一致的模式。观察到的幼苗和成年植株之间的差异可能是两个研究地点管理变化以及两个种群相关种群统计学变化的结果。我们的结果表明，反复的种群崩溃和恢复可能会强烈影响植物种群的遗传多样性和精细尺度的空间遗传结构。
