体型影响蚂蚁工蚁寿命，但不影响衰老或热致死风险
Body size predicts how long ant workers live - but not how they age or how they die from heat
- 通过野外-实验室对照实验，发现体型越大寿命越长
- 体型与衰老速度、热敏感性无显著关联，但热致死率在20℃以上急剧上升
- 昼夜节律和进化谱系比体型更关键，适合研究气候变化影响的学者参考
在社会性昆虫中，死亡风险包含多个独立维度：寿命长度、衰老轨迹和热脆弱性。我们对18种澳大利亚蚂蚁进行了配对野外-实验室生存实验（共2,363个群体-天观测，1,148只工蚁）。体型显著预测寿命长度（Cox HR = 0.67，p = 0.002），而巢群大小（p = 0.60）和体型×温度交互作用（p = 0.72）无明显调节效应。体型×觅食率存在微弱但显著的交互作用（LRT p = 0.014），表明内在生理机制仍是体型-长寿关系最简洁解释，但生态背景可能起辅助作用。衰老轨迹与昼夜节律相关而非体型：晨间活动物种衰老最快（Kruskal-Wallis p = 0.009；晨间vs.黄昏期p = 0.002），与体质量无关（Spearman p = 0.32）。热危害在20℃以上趋于平台期（Delta AIC = -38；p < 0.001），其中Rhytidoponera属（Ectatomminae）在此平台之上表现出更高热敏感性（每升高1℃死亡率上升5%，p = 0.015）。因此，昼夜节律和谱系身份是气候相关性的主要维度，尽管它们高度共线（Cramer's V = 0.85）。结果表明，体型仅反映死亡风险的一个方面，若忽略衰老与热敏感性与体型的解耦，基于体型的脆弱性指数可能误判物种排序。
原文摘要 · Abstract (English)
In social insects, mortality risk comprises distinct components that may not share the same predictors: lifespan duration, senescence trajectory, and thermal vulnerability. We tested these three axes in 18 Australian ant species using paired field-laboratory survival assays (2,363 cohort-day observations; 1,148 workers). Body size predicted duration (Cox HR = 0.67, p = 0.002), while colony size (p = 0.60) and the size x temperature interaction (p = 0.72) showed no detectable moderating effect. A weak but significant size x foraging-rate interaction was detected (LRT p = 0.014), suggesting that intrinsic physiology remains the most parsimonious explanation for the main size-longevity pattern, although ecological context may contribute. Senescence trajectory was associated with circadian niche rather than size: it was steepest in matinal species (Kruskal-Wallis p = 0.009; matinal vs. crepuscular p = 0.002) and was uncorrelated with body mass (Spearman p = 0.32). Thermal hazard plateaued above 20 degrees C (Delta AIC = -38; p < 0.001), with elevated thermal sensitivity in Rhytidoponera (Ectatomminae) above the plateau (5% per degree C, p = 0.015). Circadian regime and lineage identity, not body size, therefore emerge as the most climate-relevant axes, although they are strongly collinear (Cramer's V = 0.85). These results show that body size captures only one dimension of mortality risk and that size-based vulnerability indices may misrank taxa when senescence and thermal sensitivity are decoupled from body size.
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