Microhabitat and body size effects on heat tolerance: implications for responses to climate change (army ants: Formicidae, Ecitoninae)
Microhabitat and body size effects on heat tolerance: implications for responses to climate change (army ants: Formicidae, Ecitoninae)
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DOI：
10.1111/1365-2656.12388
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发表时间：
2015-09-01
影响因子：
4.8
通讯作者：
O'Donnell, Sean
中科院分区：
文献类型：
--
作者：
Baudier, Kaitlin M.;Mudd, Abigail E.;O'Donnell, Sean
通过考虑影响物种耐热性的生态因素，预测生物和种群对气候变化反应的模型可能会得到改进。物种在微生境使用上的差异会使动物暴露在给定地点的不同热选择环境中，并可能导致共域物种进化出不同的耐热性。我们测试了这样一种假设，即物种在身体大小和微生境使用方面的差异(地上和地下活动)将对应于热耐力的差异(最高临界温度：CTmax)。土壤的热缓冲作用可以减少地下活动物种在极端高温下的暴露。我们预测，体型较大的个体和物种具有更高的CTmax，物种的平均CTmax将与地上活动程度呈正相关。我们以新热带军蚁(蚁科：蚁亚科)为模型。行军蚁在微生境的使用上存在差异，从主要在地下的到主要在地面上活动的物种，并且高度多态。我们收集了行军蚂蚁栖息地地上和地下温度的数据，以测试微生境温度差异，并对具有不同表面活动程度和物种内和物种间不同体型的行军蚂蚁物种进行了CTmax分析。然后，我们测试了微生境的使用是否与物种在CTmax上的差异有关，以及对于大小重叠的物种，微生境是否比身体大小更好地预测CTmax。无论是对原始数据还是在考虑到系统发育的影响后，微生境的使用都是物种耐热上限的一个非常显著的预测因子。地下物种对温度更敏感，最高临界温度(CTmax)更低。每个物种中最小的工蚁耐热性最差，但地下物种的CTmax随体大小的变化幅度更大。对于大小重叠的物种，典型的微生境对CTmax的预测作用强于身体大小。与土壤表面相比，10厘米深的底土对于地下蚂蚁来说是一个显著缓和的热环境，而对于最热敏感的军蚁种姓来说，最高地表突袭温度有时超过了CTmax。我们得出结论，同域物种在热生理上的差异与微生境的利用相对应。这些模式应该在物种和群落对温度变化和气候变化的反应模型中考虑在内。
Models that predict organismal and population responses to climate change may be improved by considering ecological factors that affect species thermal tolerance. Species differences in microhabitat use can expose animals to diverse thermal selective environments at a given site and may cause sympatric species to evolve different thermal tolerances. We tested the hypothesis that species differences in body size and microhabitat use (above- vs. below-ground activity) would correspond to differences in thermal tolerance (maximum critical temperatures: CTmax). Thermal buffering effects of soil can reduce exposure to extreme high temperatures for below-ground active species. We predicted larger-bodied individuals and species would have higher CTmax and that species mean CTmax would covary positively with degree of above-ground activity. We used Neotropical army ants (Formicidae: Ecitoninae) as models. Army ants vary in microhabitat use from largely subterranean to largely above-ground active species and are highly size polymorphic. We collected data on above- and below-ground temperatures in habitats used by army ants to test for microhabitat temperature differences, and we conducted CTmax assays for army ant species with varying degrees of surface activity and with different body sizes within and between species. We then tested whether microhabitat use was associated with species differences in CTmax and whether microhabitat was a better predictor of CTmax than body size for species that overlapped in size. Microhabitat use was a highly significant predictor of species' upper thermal tolerance limits, both for raw data and after accounting for the effects of phylogeny. Below-ground species were more thermally sensitive, with lower maximum critical temperatures (CTmax). The smallest workers within each species were the least heat tolerant, but the magnitude of CTmax change with body size was greater in below-ground species. Species-typical microhabitat was a stronger predictor of CTmax than body size for species that overlapped in size. Compared to the soil surface, 10-cm subsoil was a significantly moderated thermal environment for below-ground army ants, while maximum surface raid temperatures sometimes exceeded CTmax for the most thermally sensitive army ant castes. We conclude sympatric species differences in thermal physiology correspond to microhabitat use. These patterns should be accounted for in models of species and community responses to thermal variation and climate change.