Dietz Hansjörg, Fischer Markus, Schmid Bernhard
Julius-von-Sachs-Institut für Biowissenschaften, Lehrstuhl für Botanik II -Ökophysiologie und Vegetationsökologie, Julius-von-Sachs-Platz 3, D-97082 Würzburg, Germany e-mail:
Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland, , , , , , CH.
Oecologia. 1999 Aug;120(2):225-234. doi: 10.1007/s004420050852.
The population history of a 9-year-old roadside population of the invasive plant Bunias orientalis was reconstructed by demographic analysis including size, position, age (determined by herbchronology) and RAPD-PCR patterns of individual plants. We evaluated emerging patterns of population growth and genetic structure during a full period of population development under typical site conditions (anthropogenic disturbance) and their possible consequences for the invasion potential of the species. The population has grown rapidly and continuously (though with slowing geometric population increase) during the 9 years since its foundation, filling the space available in the study area. Genetic variation (RAPD markers) was already high in the founder cohorts and remained at the same level throughout population development (variance fluctuations <15%). Both results may be related to the mowing management at the site which seems to promote population growth of B. orientalis relative to other co-occuring species and to prevent the genetic drift and the development of spatial genetic structure that would be expected under isolation-by-distance models. Large founder plants had comparatively low genetic variance and were more closely related to younger cohorts than were small founder plants, indicating that selection acted during population development. Overall, the current anthropogenic disturbance regimes may contribute to high genetic variability by artificially increasing gene flow and thereby promoting the adaptability of invasive species to the often unpredictable conditions at disturbed sites. Our approach using retrospective demographic investigation allows the detection of spatio-temporal microscale patterns in genetic and phenotypic variation. Thus it allows a thorough understanding of local invasions of perennial herbaceous plants.
通过对个体植物的大小、位置、年龄（由草本年代学确定）和RAPD-PCR模式进行人口统计学分析，重建了入侵植物东方补骨脂9年路边种群的种群历史。我们评估了在典型场地条件（人为干扰）下种群发育全过程中种群增长和遗传结构的新兴模式，以及它们对该物种入侵潜力的可能影响。自建立以来的9年里，该种群迅速且持续增长（尽管几何种群增长有所放缓），占据了研究区域内的可用空间。奠基群体中的遗传变异（RAPD标记）已经很高，并且在种群发育过程中保持在同一水平（方差波动<15%）。这两个结果可能都与该场地的割草管理有关，割草管理似乎相对于其他共存物种促进了东方补骨脂的种群增长，并防止了遗传漂变和空间遗传结构的发展，而在距离隔离模型下预计会出现这种情况。大型奠基植物的遗传方差相对较低，并且与年轻群体的亲缘关系比小型奠基植物更密切，这表明在种群发育过程中存在选择作用。总体而言，当前的人为干扰状况可能通过人为增加基因流，从而促进入侵物种对受干扰场地通常不可预测条件的适应性，导致高遗传变异性。我们使用回顾性人口统计学调查的方法能够检测遗传和表型变异中的时空微观尺度模式。因此，它有助于深入理解多年生草本植物的局部入侵情况。
