Plastic collective endothermy in a complex animal society (army ant bivouacs: Eciton burchellii parvispinum)

Endothermic animals do not always have a single adaptive internal temperature; some species exhibit plastic homeostasis, adaptively allowing body temperature to drop when thermoregulatory costs are high. Like large-bodied endotherms, some animal societies exhibit collective thermal homeostasis. We tested for plasticity of thermoregulation in the self-assembled temporary nests (bivouacs) of army ants. We measured core bivouac temperatures under a range of environmental conditions and at different colony developmental (larval vs. pupal brood) stages. Contrary to previous assertions, bivouacs were not perfect thermoregulators in all developmental stages. Instead, bivouacs functioned as superorganismal facultative endotherms, using a combination of site choice and context-dependent metabolic heating to adjust core temperatures across an elevational cline in ambient temperature. When ambient temperature was low, the magnitude of metabolic heating was dependent on colony developmental stage: ...恒温动物（endothermic animals）并非始终维持单一的适应性体内温度；部分物种会表现出可塑性体温稳态，当体温调节成本过高时，可适应性地降低体温。与大体型恒温动物类似，部分动物社群也会呈现出集体性体温稳态。本研究针对行军蚁（army ants）自行构筑的临时巢穴（bivouacs），开展了体温调节可塑性相关测试。我们在多种环境条件下，以及蚁群不同发育阶段（幼虫育幼期 vs. 蛹期育幼期）测量了蚁团巢的核心温度。与此前的学术论断相悖，蚁团巢并非在所有发育阶段都能实现完美的体温调节。实际上，蚁团巢以超个体兼性恒温动物的形态发挥功能，通过结合选址策略与情境依赖性代谢产热，在环境温度随海拔梯度变化的范围内调节核心温度。当环境温度较低时，代谢产热的强度取决于蚁群的发育阶段：……