Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University, 55128 Mainz, Germany
Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University, 55128 Mainz, Germany.
J Exp Biol. 2018 May 11;221(Pt 9):jeb171488. doi: 10.1242/jeb.171488.
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 CHCs. 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, and , 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 those observed under constant-cool conditions in , but led to entirely different profiles in , 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. Although 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.
陆生节肢动物通过一层表皮碳氢化合物 (CHC) 实现防水。同时，CHC 也作为通讯信号。为了在不同气候条件下保持防水性，昆虫会调整其 CHC 层的化学组成，但这可能会影响通过 CHC 的通讯。CHC 的详细适应变化以及这些变化如何影响它们的物理性质仍不清楚。在这里，我们研究了两种密切相关的蚂蚁物种在恒温恒湿和温度湿度波动条件下的适应情况，这两种蚂蚁的 CHC 图谱不同。我们测量了适应如何影响 CHC 组成和粘度，以及蚂蚁的耐旱性。在这两个物种中，CHC 组成对温度条件表现出强烈的、可预测的反应。温暖适应的个体具有更高比例的线性烷烃，以及更少的甲基支链或不饱和 CHC。这些变化与温暖适应的蚂蚁的 CHC 固体含量和粘度升高相一致。温度波动导致的影响与在恒温条件下观察到的影响相似，但在 中导致了完全不同的图谱，这表明波动和恒定条件构成了非常不同的挑战。对干燥条件的适应导致 CHC 的绝对量增加，从而提高了蚂蚁的耐旱性，而温度适应则没有。因此，温度引起的 CHC 变化不能仅用防水的需要来解释。尽管这些变化可能不是适应性的，但我们提出它们是为了维持 CHC 粘度的恒定，这可能对通讯和其他功能至关重要。
