Department of Biology, University of York, York, UK.
York Cross-disciplinary Centre for Systems Analysis, University of York, York, UK.
J Anim Ecol. 2021 Jan;90(1):143-152. doi: 10.1111/1365-2656.13198. Epub 2020 Mar 30.
Animal social structure is shaped by environmental conditions, such as food availability. This is important as conditions are likely to change in the future and changes to social structure can have cascading ecological effects. Wood ants are a useful taxon for the study of the relationship between social structure and environmental conditions, as some populations form large nest networks and they are ecologically dominant in many northern hemisphere woodlands. Nest networks are formed when a colony inhabits more than one nest, known as polydomy. Polydomous colonies are composed of distinct sub-colonies that inhabit spatially distinct nests and that share resources with each other. In this study, we performed a controlled experiment on 10 polydomous wood ant (Formica lugubris) colonies to test how changing the resource environment affects the social structure of a polydomous colony. We took network maps of all colonies for 5 years before the experiment to assess how the networks changes under natural conditions. After this period, we prevented ants from accessing an important food source for a year in five colonies and left the other five colonies undisturbed. We found that preventing access to an important food source causes polydomous wood ant colony networks to fragment into smaller components and begin foraging on previously unused food sources. These changes were not associated with a reduction in the growth of populations inhabiting individual nests (sub-colonies), foundation of new nests or survival, when compared with control colonies. Colony splitting likely occurred as the availability of food in each nest changed causing sub-colonies to change their inter-nest connections. Consequently, our results demonstrate that polydomous colonies can adjust to environmental changes by altering their social network.
动物的社会结构受环境条件的影响，例如食物的可获得性。这一点很重要，因为未来的条件很可能会发生变化，而社会结构的变化可能会产生级联的生态效应。木蚁是研究社会结构与环境条件之间关系的一个有用分类群，因为有些种群形成了大型的巢网络，并且在许多北半球的林地中具有生态优势。当一个蚁群占据多个巢时，就会形成巢网络，这被称为多巢现象。多巢蚁群由居住在空间上不同巢穴的不同亚群组成，这些亚群相互共享资源。在这项研究中，我们对 10 个多巢木蚁（Formica lugubris）蚁群进行了一项对照实验，以测试改变资源环境如何影响多巢蚁群的社会结构。在实验前，我们对所有蚁群进行了 5 年的网络地图绘制，以评估网络在自然条件下的变化情况。在这段时间之后，我们在五个蚁群中阻止蚂蚁获取一年的重要食物来源，而让另外五个蚁群不受干扰。我们发现，阻止蚂蚁获取重要食物来源会导致多巢木蚁蚁群网络分裂成更小的部分，并开始在以前未使用过的食物来源上觅食。与对照蚁群相比，这些变化并没有导致居住在单个巢中的种群（亚群）的生长、新巢的建立或生存减少。当每个巢中的食物供应发生变化时，蚁群分裂可能会发生，导致亚群改变它们的巢间连接。因此，我们的研究结果表明，多巢蚁群可以通过改变其社会网络来适应环境变化。
