Data from: Coping with the climate: cuticular hydrocarbon acclimation of ants under constant and fluctuating conditions

Terrestrial arthropods achieve waterproofing by a layer of cuticular hydrocarbons (CHCs). At the same time, CHCs also serve as communication signals. To maintain waterproofing under different climate conditions, insects adjust the chemical composition of their CHC layer, but this may affect the communication via CHC. The detailed acclimatory changes of CHCs and how these influence their physical properties are still unknown. Here, we studied acclimation in two closely related ant species with distinct CHC profiles, Myrmica rubra and Myrmica ruginodis, in response to constant or fluctuating temperature and humidity regimes. We measured how acclimation affected CHC composition and viscosity, and the ants’ drought survival. In both species, CHC composition showed strong, predictable responses to temperature regimes. Warm-acclimated individuals had higher proportions of linear alkanes, and less methyl-branched or unsaturated CHCs. These changes coincided with higher solid content and viscosity of CHCs in warm-acclimated ants. Temperature fluctuation caused effects similar to constant-cool conditions in M. rubra, but led to entirely different profiles in M. ruginodis, suggesting that fluctuating and constant conditions pose very different challenges. Acclimation to dry conditions led to higher absolute amounts of CHCs, which increased the ants’ drought survival, whereas temperature acclimation did not. Hence, the temperature-induced CHC changes cannot be explained by the need for waterproofing alone. While these changes could be non-adaptive, we propose that they serve to maintain a constant CHC viscosity, which may be essential for communication and other functions.陆生节肢动物依靠表皮碳氢化合物（cuticular hydrocarbons, CHCs）层实现防水功能。与此同时，CHCs还可作为交流信号。为在不同气候条件下维持防水性能，昆虫会调整其CHC层的化学组成，但这一过程可能会干扰基于CHCs的交流活动。目前，学界对于CHCs的具体适应性驯化变化，以及这些变化如何影响其物理特性仍不甚明晰。 本研究选取两种亲缘关系相近但CHC谱型存在显著差异的蚂蚁——Myrmica rubra和Myrmica ruginodis——，探究其在恒定或波动的温湿度条件下的适应性驯化情况。我们测定了驯化如何影响CHCs的组成、黏度，以及蚂蚁的干旱存活率。 两种蚂蚁的CHC组成均对温度条件表现出强烈且可预测的响应。经温驯化的个体体内，直链烷烃占比更高，而甲基支链或不饱和CHCs的占比更低。这类变化与温驯化蚂蚁体内CHCs的固体成分占比及黏度升高相吻合。在M. rubra中，温度波动产生的效应与恒定低温条件相似；但在M. ruginodis中，温度波动则导致了完全不同的CHC谱型，这表明波动与恒定的环境条件带来了截然不同的生存挑战。 干旱驯化会使蚂蚁体内CHCs的绝对含量升高，进而提升其干旱存活率；而温度驯化则未产生此类效应。因此，温度诱导的CHC变化无法仅通过防水需求来解释。尽管这类变化可能不具备适应性，但我们推测其作用是维持CHCs的恒定黏度，而这或许对于交流及其他生理功能至关重要。