Laboratory of Aquatic Ecology, Evolution and Conservation, Department of Biology, University of Leuven, Leuven, Belgium.
Heredity (Edinb). 2013 Nov;111(5):422-9. doi: 10.1038/hdy.2013.64. Epub 2013 Jul 3.
Many ectothermic species are currently expanding their geographic range due to global warming. This can modify the population genetic diversity and structure of these species because of genetic drift during the colonization of new areas. Although the genetic signatures of historical range expansions have been investigated in an array of species, the genetic consequences of natural, contemporary range expansions have received little attention, with the only studies available focusing on range expansions along a narrow front. We investigate the genetic consequences of a natural range expansion in the Mediterranean damselfly Coenagrion scitulum, which is currently rapidly expanding along a broad front in different directions. We assessed genetic diversity and genetic structure using 12 microsatellite markers in five centrally located populations and five recently established populations at the edge of the geographic distribution. Our results suggest that, although a marginal significant decrease in the allelic richness was found in the edge populations, genetic diversity has been preserved during the range expansion of this species. Nevertheless, edge populations were genetically more differentiated compared with core populations, suggesting genetic drift during the range expansion. The smaller effective population sizes of the edge populations compared with central populations also suggest a contribution of genetic drift after colonization. We argue and document that range expansion along multiple axes of a broad expansion front generates little reduction in genetic diversity, yet stronger differentiation of the edge populations.
由于全球变暖,许多变温动物物种目前正在扩大其地理分布范围。这可能会改变这些物种的种群遗传多样性和结构,因为在新地区的殖民过程中会发生遗传漂变。尽管已经在许多物种中研究了历史范围扩张的遗传特征,但自然的、当代的范围扩张的遗传后果却很少受到关注,仅有的可用研究集中在狭窄前沿的范围扩张上。我们研究了地中海蜻蜓 Coenagrion scitulum 自然范围扩张的遗传后果,该物种目前正在不同方向上沿着宽阔的前沿迅速扩张。我们使用 12 个微卫星标记在五个中心位置的种群和五个位于地理分布边缘的新建立的种群中评估遗传多样性和遗传结构。我们的研究结果表明,尽管在边缘种群中发现了等位基因丰富度的边际显著下降,但在该物种的范围扩张过程中遗传多样性得到了保留。尽管如此,与核心种群相比,边缘种群的遗传分化程度更高,这表明在范围扩张过程中发生了遗传漂变。与中心种群相比,边缘种群的有效种群规模较小,这也表明在殖民后遗传漂变的作用。我们认为并证明了在宽阔扩张前沿的多个轴上的扩张范围不会导致遗传多样性的大量减少,但会导致边缘种群的分化更强。