Levine Rebecca L, Verzuh Tana L, Mathewson Paul D, Porter Warren P, Kroger Bart, Monteith Kevin L
Haub School of the Environment and Natural Resources, University of Wyoming, Laramie, Wyoming, USA.
School of Computing, University of Wyoming, Laramie, Wyoming, USA.
Ecology. 2025 Jun;106(6):e70138. doi: 10.1002/ecy.70138.
Increasingly, climate change is pushing species to the limits of their thermal tolerance, with cascading effects across ecosystems. Animals use behavior to prevent these harmful physiological states, but their need and ability to do so varies with their traits. Within species, traits such as sex and reproductive status affect heat sensitivity, perhaps eliciting differences in behavioral responses to thermal extremes. We evaluated whether sex and reproductive status affected thermoregulatory behavior and its efficacy in moose (Alces alces), a heat-sensitive endotherm that relies on thermal refuge. We expected traits associated with elevated heat load would be linked to heightened selection for thermal refuge and that differences in selection would successfully alleviate differing risks of overheating. Thus, reproductive females and males, who are more heat-sensitive, would have stronger selection for thermal refuge than non-reproductive females. We assessed selection of thermal refuge at bed sites and generated biophysical models to evaluate if selection mitigated risk of overheating. Reproductive status did not elicit differences in selection by females. The sexes, however, differed in selection of the trade-off between solar cover and cooling from wind. Females selected refuge with canopy cover and avoided wind. Males did not select cover and had weaker avoidance of wind than females. Yet, both sexes were more likely to overheat in areas of low cover, even if wind speeds were high. Hence, males had weaker selection of refuge than females despite being more likely to overheat, and life history trade-offs failed to explain the sub-optimal thermoregulatory behavior. We identify sex-specific thermoregulatory trade-offs, highlighting the disproportionate effects of climate change on certain demographic groups. Moreover, we emphasize the relevance of trait-based approaches for studying changing ecosystems.
气候变化正日益将物种推向其耐热极限，并对整个生态系统产生连锁反应。动物利用行为来预防这些有害的生理状态，但它们这样做的需求和能力因其特征而异。在物种内部，性别和生殖状态等特征会影响热敏感性，这可能会引发对极端温度行为反应的差异。我们评估了性别和生殖状态是否会影响驼鹿（Alces alces）的体温调节行为及其效果，驼鹿是一种依赖热庇护所的热敏性恒温动物。我们预计与热负荷增加相关的特征会与对热庇护所的更强选择相关联，并且选择上的差异会成功减轻不同的过热风险。因此，对热更敏感的繁殖期雌性和雄性驼鹿，会比非繁殖期雌性有更强的热庇护所选择。我们评估了卧息地点对热庇护所的选择，并生成生物物理模型来评估这种选择是否减轻了过热风险。生殖状态并未引起雌性在选择上的差异。然而，在选择遮阳和乘风降温之间的权衡上，两性存在差异。雌性选择有树冠遮蔽的庇护所并避开风。雄性不选择遮蔽物，且对风的回避比雌性弱。然而，即使风速很高，在遮蔽物少的区域两性都更有可能过热。因此，尽管雄性更有可能过热，但它们对庇护所的选择比雌性弱，而且生活史权衡无法解释这种次优的体温调节行为。我们确定了特定性别的体温调节权衡，突出了气候变化对某些人口群体的不成比例影响。此外，我们强调基于特征的方法对于研究不断变化的生态系统的相关性。
