Pujol Benoit, Pannell John R
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Science. 2008 Jul 4;321(5885):96. doi: 10.1126/science.1157570.
Species range expansion reduces genetic variation at the margins of a species range and should thus compromise the adaptive potential of its marginal populations. Remarkably, this prediction has not previously been tested. Here, we show that populations of the plant Mercurialis annua, which expanded its range into Spain and Portugal from North Africa after the Pleistocene glaciation, respond to selection on a key life-history trait less well than populations from the species' historical refugium. Our results provide direct evidence of a decline in adaptive potential across the geographic range of a species after a shift in its distribution. Predicting evolutionary responses to environmental change will thus need to account for the genetic heterogeneity of species and the spatial dynamics of their geographic distributions.
物种分布范围的扩张会减少物种分布范围边缘的遗传变异，因此会损害其边缘种群的适应潜力。值得注意的是，这一预测此前尚未得到验证。在这里，我们表明，一年生植物山靛的种群，在更新世冰川作用后从北非扩展到西班牙和葡萄牙，其对关键生活史性状的选择反应不如来自该物种历史避难所的种群。我们的结果提供了直接证据，证明一个物种分布发生变化后，其整个地理范围内的适应潜力会下降。因此，预测对环境变化的进化反应将需要考虑物种的遗传异质性及其地理分布的空间动态。
