Data from: Drought-induced relocation of ant colonies and its consequences for the long-term spatial ecology of a population under stress

Maintaining a central refuge such as a nest or burrow can offer protection against environmental stressors but comes at the expense of the capacity to disperse to new locations. This trade-off with mobility can be detrimental when environmental conditions become adverse for extended periods, necessitating animals to relocate in order to track shifting niche envelopes. Long-lived ant colonies that invest in the construction of large nests are especially susceptible to changing environmental conditions. The Australian meat ant, Iridomyrmex purpureus, build large terrestrial nests at sites that balance shade and solar exposure. Long-term study of a population of meat ants showed low nest turnover and a stable spatial distribution of nests across typical rainfall years. With the onset of drought, a dramatic surge in the production of new nests occurred through a process of budding that far exceeded historic trends. This appears to have allowed colonies to relocate nests into areas with more favourable microclimate conditions in a strategy reminiscent of the production of runners in stressed plants. The consequence has also been the packing of nests into a narrow habitable zone that has resulted in an apparent increase in competition among large rival colonies. Following the break in drought and the thinning of some nests through abandonment, competition has progressively eased in later years. The surge in nest budding triggered by acute environmental stress in this population offers a possible strategy for long-lived colonies to effectively migrate across the landscape. With changes in environmental conditions becoming more frequent and severe with the climate crisis, any strategy available to central place foragers to track windows of preferred conditions are likely to become increasingly important.

维持诸如巢穴或洞穴一类的核心庇护所，可为动物提供抵御环境胁迫的保护，但代价是其向新区域扩散的能力受到限制。这种与移动能力相关的权衡，在环境条件长期恶化时会产生不利影响，此时动物必须迁徙以追踪不断变化的适宜生态位范围（niche envelopes）。以建造大型巢穴为投资的长寿蚁群，对环境变化尤为敏感。澳洲肉食蚁（Iridomyrmex purpureus）会在兼顾遮阴与日照的位点建造大型陆生巢穴。对该肉食蚁种群的长期研究表明，在典型降雨年份，其巢穴周转率较低且巢穴空间分布稳定。随着干旱的到来，通过分巢过程产生的新巢数量急剧激增，远超历史趋势水平。这一策略似乎让蚁群得以将巢穴迁至微气候更适宜的区域，类似于受胁迫植物产生匍匐茎的生存策略。其结果是巢穴被集中压缩至狭窄的适宜生境带中，这导致大型敌对蚁群间的竞争显著加剧。随着干旱结束，部分巢穴因被弃用而减少，后续年份中的竞争也逐步缓解。该种群在急性环境胁迫下触发的巢群分建激增现象，为长寿蚁群实现跨景观有效迁徙提供了一种可行策略。随着气候危机导致环境变化愈发频繁且剧烈，对于中心地觅食者（central place forager）而言，任何能够追踪适宜环境窗口的策略，其重要性都将日益凸显。