Department of Community Ecology, Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012, Bern, Switzerland.
Glob Chang Biol. 2016 Jan;22(1):228-36. doi: 10.1111/gcb.13091. Epub 2015 Nov 18.
Cities are growing rapidly, thereby expected to cause a large-scale global biotic homogenization. Evidence for the homogenization hypothesis is mostly derived from plants and birds, whereas arthropods have so far been neglected. Here, I tested the homogenization hypothesis with three insect indicator groups, namely true bugs, leafhoppers, and beetles. In particular, I was interested whether insect species community composition differs between urban and rural areas, whether they are more similar between cities than between rural areas, and whether the found pattern is explained by true species turnover, species diversity gradients and geographic distance, by non-native or specialist species, respectively. I analyzed insect species communities sampled on birch trees in a total of six Swiss cities and six rural areas nearby. In all indicator groups, urban and rural community composition was significantly dissimilar due to native species turnover. Further, for bug and leafhopper communities, I found evidence for large-scale homogenization due to urbanization, which was driven by reduced species turnover of specialist species in cities. Species turnover of beetle communities was similar between cities and rural areas. Interestingly, when specialist species of beetles were excluded from the analyses, cities were more dissimilar than rural areas, suggesting biotic differentiation of beetle communities in cities. Non-native species did not affect species turnover of the insect groups. However, given non-native arthropod species are increasing rapidly, their homogenizing effect might be detected more often in future. Overall, the results show that urbanization has a negative large-scale impact on the diversity specialist species of the investigated insect groups. Specific measures in cities targeted at increasing the persistence of specialist species typical for the respective biogeographic region could help to stop the loss of biodiversity.
城市正在迅速发展，预计这将导致大规模的全球生物同质化。同质化假说的证据主要来自植物和鸟类，而节肢动物迄今为止一直被忽视。在这里，我用三个昆虫指示类群，即真昆虫、叶蝉和甲虫，来检验同质化假说。我特别感兴趣的是昆虫物种群落组成是否在城市和农村地区之间存在差异，它们在城市之间是否比在农村地区更相似，以及发现的模式是否分别由真正的物种更替、物种多样性梯度和地理距离、非本地或特有物种来解释。我分析了在瑞士六个城市和六个附近农村地区的桦树上采集的昆虫物种群落。在所有的指示类群中，由于本地物种更替，城市和农村的群落组成存在显著差异。此外，对于昆虫和叶蝉群落，我发现了由于城市化导致的大规模同质化的证据，这是由城市中特化物种的物种更替减少驱动的。甲虫群落的物种更替在城市和农村地区之间相似。有趣的是，当从分析中排除甲虫的特有物种时，城市比农村地区更具异质性，这表明甲虫群落在城市中具有生物分化。特有物种的非本地物种不会影响昆虫类群的物种更替。然而，鉴于非本地节肢动物物种正在迅速增加，它们的同质化效应在未来可能会更频繁地被检测到。总的来说，这些结果表明，城市化对所研究的昆虫类群的多样性特有物种具有负面的大规模影响。城市中针对增加特定生物地理区域特有的特有物种的持久性的具体措施，可能有助于阻止生物多样性的丧失。
