People and Wildlife Research Group, School of Biological Sciences, University of Reading, Whiteknights, Reading, Berkshire, RG6 6AS, UK.
Sci Rep. 2020 Apr 14;10(1):6406. doi: 10.1038/s41598-020-62422-z.
The modification of habitats in urban areas is thought to alter patterns of species interactions, by filtering specialist species and those at higher trophic levels. However, empirical studies addressing these hypotheses remain limited in scope and number. This work investigates (1) how main urban land uses affect predator-prey and mutualistic interactions, and (2) how specialist and generalist predators respond to size and availability of urban green spaces. In a large town in the UK, experimental colonies of ant-attended Black bean aphid Aphis fabae and non-ant-attended Pea aphid Acyrthosiphon pisum were monitored over two years. Ants were more frequently found in highly urbanised sites; however mutualistic ants were also more often encountered when the habitat was more plant diverse. Aphids were not affected by urban land uses, but A. fabae numbers were positively related to the presence of mutualists, and so indirectly affected by urbanisation. Predators were the only group negatively affected by increased urbanisation, and specialist species were positively related to increased proportion of urban green areas within the habitats. While this work supports the hypothesis that specialist predators are negatively affected by urbanisation, we also show that a fundamental ecological interaction, mutualism, is affected by urbanisation.
城市地区生境的改变被认为会通过过滤特化种和较高营养级的物种来改变物种相互作用的模式。然而，针对这些假设的实证研究在范围和数量上仍然有限。这项工作调查了（1）主要城市土地利用如何影响捕食者-猎物和互利共生关系，以及（2）特化和一般化捕食者如何响应城市绿地的大小和可用性。在英国的一个大城镇，对受蚂蚁照顾的黑大豆蚜虫 Aphis fabae 和不受蚂蚁照顾的豌豆蚜虫 Acyrthosiphon pisum 的实验殖民地进行了两年的监测。蚂蚁更频繁地出现在高度城市化的地点；然而，当栖息地植物多样性更高时，互利共生的蚂蚁也更常见。蚜虫不受城市土地利用的影响，但 A. fabae 的数量与互利共生者的存在呈正相关，因此间接受到城市化的影响。捕食者是唯一受到城市化加剧负面影响的群体，而特化种与栖息地内城市绿地比例的增加呈正相关。虽然这项工作支持了特化捕食者受到城市化负面影响的假设，但我们也表明，一种基本的生态相互作用，互利共生，受到城市化的影响。
