Krauss Jochen, Schmitt Thomas, Seitz Alfred, Steffan-Dewenter Ingolf, Tscharntke Teja
Agroecology, University of Göttingen, Waldweg 26, D-37073 Göttingen, Germany.
Mol Ecol. 2004 Feb;13(2):311-20. doi: 10.1046/j.1365-294x.2003.02072.x.
Population genetic patterns of species at their range margin have important implications for species conservation. We performed allozyme electrophoresis of 19 loci to investigate patterns of the genetic structure of 17 populations (538 individuals) of the butterfly Polyommatus coridon, a monophagous habitat specialist with a patchy distribution. The butterfly and its larval food plant Hippocrepis comosa reach their northern distribution margin in the study region (southern Lower Saxony, Germany). Butterfly population size increased with host plant population size. The genetic differentiation between populations was low but significant (FST = 0.013). No isolation-by-distance was found. Hierarchical F-statistics revealed significant differentiation between a western and an eastern subregion, separated by a river valley. The combination of genetic and ecological data sets revealed that the expected heterozygosity (mean: 18.5%) decreased with increasing distance to the nearest P. coridon population. The population size of P. coridon and the size of larval food plant population had no effect on the genetic diversity. The genetic diversity of edge populations of P. coridon was reduced compared to populations from the centre of its distribution. This might be explained by (i). an increasing habitat fragmentation towards the edge of the distribution range and/or (ii). a general reduction of genetic variability towards the northern edge of its distribution.
处于分布边缘的物种的种群遗传模式对物种保护具有重要意义。我们对19个基因座进行了等位酶电泳，以研究食性单一、栖息地特殊且分布零散的蝴蝶Polyommatus coridon的17个种群（538个个体）的遗传结构模式。在研究区域（德国下萨克森州南部），这种蝴蝶及其幼虫的食草植物Hippocrepis comosa均达到了它们的北半分布边缘。蝴蝶种群数量随寄主植物种群数量的增加而增加。种群间的遗传分化程度较低但显著（FST = 0.013）。未发现距离隔离现象。分层F统计显示，在被一条河谷隔开的西部和东部子区域之间存在显著分化。遗传数据集与生态数据集相结合显示，预期杂合度（均值：18.5%）随着与最近的P. coridon种群距离的增加而降低。P. coridon的种群数量和幼虫食草植物种群数量对遗传多样性没有影响。与分布中心的种群相比，P. coridon边缘种群的遗传多样性有所降低。这可能是由于：（i）. 分布范围边缘的栖息地破碎化加剧；和/或（ii）. 分布北边缘的遗传变异性普遍降低。
