Visser Michaël, de Leeuw Maarten, Zuiderwijk Annie, Arntzen Jan W
Naturalis Biodiversity Center Leiden The Netherlands.
Ecol Evol. 2016 Dec 21;7(2):689-696. doi: 10.1002/ece3.2676. eCollection 2017 Jan.
When related species meet upon postglacial range expansion, hybrid zones are frequently formed. Theory predicts that such zones may move over the landscape until equilibrium conditions are reached. One hybrid zone observed to be moving in historical times (1950-1979) is that of the pond-breeding salamanders and in western France. We identified the ecological correlates of the species hybrid zone as elevation, forestation, and hedgerows favoring the more terrestrial and pond density favoring the more aquatic . The past movement of the zone of ca. 30 km over three decades has probably been driven by the drastic postwar reduction of the "bocage" hedgerow landscape, favoring over . No further hybrid zone movement was observed from 1979 to the present. To explain the changing dynamics of the hybrid zone, we propose that it stalled, either because an equilibrium was found at an altitude of ca. 140 m a.s.l. or due to pond loss and decreased population densities. While we cannot rule out the former explanation, we found support for the latter. Under agricultural intensification, ponds in the study area are lost at an unprecedented rate of 5.5% per year, so that remaining populations are increasingly isolated, hampering dispersal and further hybrid zone movement.
当相关物种在冰期后范围扩张时相遇，常常会形成杂交带。理论预测，此类杂交带可能会在景观中移动，直至达到平衡状态。一个在历史时期（1950 - 1979年）被观察到正在移动的杂交带是法国西部池塘繁殖蝾螈的杂交带。我们确定了该物种杂交带的生态相关因素，即海拔、森林覆盖率以及有利于更适应陆地生活的物种的树篱，还有有利于更适应水生生活的物种的池塘密度。该杂交带在三十年间约30公里的过去移动可能是由战后“树篱”景观的急剧减少所驱动，这种减少有利于[此处原文缺失具体物种信息]而非[此处原文缺失具体物种信息]。从1979年至今未观察到杂交带的进一步移动。为了解释杂交带动态变化，我们提出它停滞不前，要么是因为在海拔约140米处找到了平衡，要么是由于池塘丧失和种群密度下降。虽然我们不能排除前一种解释，但我们找到了支持后一种解释的证据。在农业集约化过程中，研究区域内的池塘正以前所未有的每年5.5%的速度消失，因此剩余的[此处原文缺失具体物种信息]种群越来越孤立，阻碍了扩散和杂交带的进一步移动。
