Merckx Thomas, Van Dyck Hans, Karlsson Bengt, Leimar Olof
Department of Biology, University of Antwerp, Universiteitsplein 1, B-26100 Antwerp, Belgium.
Proc Biol Sci. 2003 Sep 7;270(1526):1815-21. doi: 10.1098/rspb.2003.2459.
As landscapes change, mobility patterns of species may alter. Different mechanistic scenarios may, however, lead to particular patterns. Here, we tested conflicting predictions from two hypotheses on butterfly movements in relation to habitat fragmentation. According to the resource distribution hypothesis, butterflies in more fragmented landscapes would have higher levels of mobility as resources are more scattered. However, these butterflies could have lower levels of mobility as they experience 'hard' habitat boundaries more frequently (i.e. higher crossing costs) compared with butterflies in landscapes with continuous habitat; i.e. the behaviour-at-boundaries hypothesis. We studied movements, habitat boundary crossing and habitat preference of laboratory-reared individuals of Pararge aegeria that originated from woodland and agricultural landscapes, by using an experimental landscape as a common environment (outdoor cages) to test the predictions, taking into account sexual differences and weather. Woodland butterflies covered longer distances, were more prone to cross open-shade boundaries, travelled more frequently between woodland parts of the cages and were more at flight than agricultural butterflies. Our results support the behaviour-at-boundaries hypothesis, with 'softer' boundaries for woodland landscapes. Because the butterflies were reared in a common environment, the observed behavioural differences rely on heritable variation between populations from woodland and agricultural landscapes.
随着景观的变化，物种的移动模式可能会改变。然而，不同的机制情景可能会导致特定的模式。在这里，我们测试了关于蝴蝶移动与栖息地破碎化关系的两个假设所产生的相互矛盾的预测。根据资源分布假设，在破碎化程度更高的景观中的蝴蝶，由于资源更加分散，其移动性会更高。然而，与生活在连续栖息地景观中的蝴蝶相比，这些蝴蝶可能由于更频繁地遇到“硬性”栖息地边界（即更高的穿越成本）而具有较低的移动性；即边界行为假设。我们通过使用实验景观作为共同环境（户外笼子），研究了源自林地和农业景观的实验室饲养的艾氏波眼蝶个体的移动、栖息地边界穿越和栖息地偏好，以测试这些预测，同时考虑了性别差异和天气。林地蝴蝶飞行的距离更长，更倾向于穿越开阔与阴凉的边界，在笼子的林地部分之间飞行得更频繁，并且比农业蝴蝶更活跃。我们的结果支持边界行为假设，林地景观具有“更软性”的边界。由于蝴蝶是在共同环境中饲养的，观察到的行为差异依赖于林地和农业景观种群之间的遗传变异。
