Nürnberger Beate, Harrison Richard G
Section of Ecology and Systematics, Cornell University, Ithaca, New York, 14853.
Evolution. 1995 Apr;49(2):266-275. doi: 10.1111/j.1558-5646.1995.tb02239.x.
The spatial population structure of the pond-living water beetle Dineutus assimilis (Coleoptera: Gyrinidae) was investigated through a field study of population dynamics and dispersal, with a concurrent assessment of the spatial distribution of mitochondrial DNA (mtDNA) restriction-fragment-length polymorphism (RFLP). A comprehensive 2-yr survey within a 60-km study area revealed pronounced fluctuations in local abundances, including extinctions and colonizations. The recapture of marked individuals showed that dispersal among ponds is frequent in both males and females and connects populations on a large geographic scale (maximum observed flight distance: 20 km). The population structure of D. assimilis is thus characterized by both pronounced genetic drift and frequent gene flow. Together, these two forces generate a pattern of very local and transient genetic differentiation. Mitochondrial DNA samples collected within a few kilometers indicate highly significant spatial structure, if newly founded demes or those that experienced recent bottlenecks are included. These results based on four demes within the study area were placed into a regional context by further samples collected at distances of 100 km and 200 km. F estimates computed on increasing spatial scales were variable but showed no increasing trend. Thus, gene flow exerts a strong homogenizing force over a wide geographic range but is counteracted locally by genetic drift. These findings highlight the need to supplement estimates of F with additional data to arrive at valid interpretations of the genetic information. More generally, this study raises questions about how to capture the relevant features of dynamic, subdivided populations to understand their evolutionary dynamics.
通过对池塘生活的水甲虫Dineutus assimilis（鞘翅目：豉甲科）种群动态和扩散的实地研究，并同时评估线粒体DNA（mtDNA）限制性片段长度多态性（RFLP）的空间分布，对其空间种群结构进行了调查。在一个60公里的研究区域内进行的为期两年的全面调查揭示了当地丰度的显著波动，包括灭绝和定殖。对标记个体的重新捕获表明，雄性和雌性在池塘之间的扩散都很频繁，并且在大地理尺度上连接种群（观察到的最大飞行距离：20公里）。因此，D. assimilis的种群结构具有明显的遗传漂变和频繁的基因流特征。这两种力量共同产生了一种非常局部和短暂的遗传分化模式。如果包括新建立的种群或经历过近期瓶颈的种群，在几公里范围内收集的线粒体DNA样本显示出高度显著的空间结构。通过在100公里和200公里距离处收集的进一步样本，将基于研究区域内四个种群的这些结果置于区域背景中。在不断增加的空间尺度上计算的F估计值是可变的，但没有显示出增加的趋势。因此，基因流在广泛的地理范围内发挥着强大的均质化作用，但在局部受到遗传漂变的抵消。这些发现强调了需要用额外的数据补充F估计值，以便对遗传信息做出有效的解释。更普遍地说，这项研究提出了关于如何捕捉动态、细分种群的相关特征以理解其进化动态的问题。
