Division for Ecology & Biodiversity, School of Biological Sciences, The University of Hong Kong, Hong Kong S.A.R, China.
Biology Centre of the Czech Academy of Sciences, Institute of Entomology, České Budějovice, Czech Republic.
J Anim Ecol. 2021 Dec;90(12):2888-2900. doi: 10.1111/1365-2656.13589. Epub 2021 Oct 3.
The thermal biology of ectotherms largely determines their abundance and distributions. In general, tropical species inhabiting warm and stable thermal environments tend to have low tolerance to cold and variable environments, which may restrict their expansion into temperate climates. However, the distribution of some tropical species does extend into cooler areas such as tropical borders and high elevation tropical mountains. Behavioural and morphological differences may therefore play important roles in facilitating tropical species to cope with cold and variable climates at tropical edges. We used field-validated biophysical models to estimate body temperatures of butterflies across elevational gradients at three sites in southern China and assessed the contribution of behavioural and morphological differences in facilitating their persistence in tropical and temperate climates. We investigated the effects of temperature on the activity of 4,844 individuals of 144 butterfly species along thermal gradients and tested whether species of different climatic affinities-tropical and widespread (distributed in both temperate and tropical regions)-differed in their thermoregulatory strategies (i.e. basking). In addition, we tested whether thermally related morphology or the strength of solar radiation (when butterflies were recorded) was related to such differences. We found that activities of tropical species were restricted (low abundance) at low air temperatures compared to widespread species. Active tropical species were also more likely to bask at cooler body temperatures than widespread species. Heat gain from behavioural thermoregulation was higher for tropical species (when accounting for species abundance), and heat gain correlated with larger thorax widths but not with measured solar radiation. Our results indicate that physiological intolerance to cold temperatures in tropical species may be compensated through behavioural and morphological responses in thermoregulation in variable subtropical environments. Increasing climatic variability with climate change may render tropical species more vulnerable to cold weather extremes compared to widespread species that are more physiologically suited to variable environments.
变温动物的热生物学在很大程度上决定了它们的丰度和分布。一般来说，生活在温暖而稳定热环境中的热带物种对寒冷和多变的环境的耐受性较低，这可能限制了它们向温带气候的扩张。然而，一些热带物种的分布确实扩展到了较凉爽的地区，如热带边界和高海拔热带山脉。因此，行为和形态上的差异可能在促进热带物种适应热带边缘的寒冷和多变气候方面发挥重要作用。我们使用经过实地验证的生物物理模型来估算中国南部三个地点蝴蝶在海拔梯度上的体温，并评估行为和形态差异在促进它们在热带和温带气候中生存方面的作用。我们研究了温度对 144 种蝴蝶 4844 个个体在热梯度上活动的影响，并测试了不同气候亲缘性的物种（热带和广布种，分布在热带和温带地区）在其体温调节策略（即晒太阳）上是否存在差异。此外，我们还测试了与温度相关的形态或太阳辐射强度（当蝴蝶被记录时）是否与这些差异有关。我们发现，与广布种相比，热带种在低空气温度下的活动受到限制（丰度较低）。活跃的热带种在较凉爽的体温下也更有可能晒太阳，而广布种则不然。行为体温调节产生的热量增益在热带种中更高（考虑到物种丰度），并且热量增益与更大的胸部宽度相关，而与测量的太阳辐射无关。我们的结果表明，热带物种对低温的生理不耐受可能通过在多变的亚热带环境中进行行为和形态体温调节来得到补偿。随着气候变化，气候变异性的增加可能会使热带物种比更适应多变环境的广布种更容易受到寒冷天气极端事件的影响。
