Arambourou Hélène, Sanmartín-Villar Iago, Stoks Robby
Irstea, Research Unit MAEP (Freshwater Systems, Ecology and Pollution), 5 Rue de la Doua, CS70077, 69626, Villeurbanne Cedex, France.
Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Ch. Debériotstraat 32, 3000, Louvain, Belgium.
Oecologia. 2017 May;184(1):279-291. doi: 10.1007/s00442-017-3846-z. Epub 2017 Feb 25.
Two key insights to better assess the ecological impact of global warming have been poorly investigated to date: global warming effects on the integrated life cycle and effects of heat waves. We tested the effect of a simulated mild (25 °C) and severe (30 °C) heat wave experienced during the larval stage on the flight ability of the damselfly Ischnura elegans. To get a mechanistic understanding of how heat stress may translate into reduced post-metamorphic flight ability, we evaluated the hypothesized mediatory role of adult size-related traits, and also tested alternative pathways operating through changes in wing shape and two flight-related traits (both relative fat and flight muscle contents). Exposure to a heat wave, and particularly the severe one, shortened the larval stage, reduced adult size-related traits and modified the wing shape but did not significantly affect emergence success, relative fat content and relative flight muscle mass. Notably, the heat wave negatively affected all components of flight ability. Unexpectedly, the heat wave did not reduce flight ability through reducing size. Instead, we identified a novel size-independent mechanism bridging metamorphosis to link larval environment and adult flight ability in males: through affecting wing shape. The present study advances mechanistic insights in the still poorly understood coupling of life stages across metamorphosis. Additionally, our results underscore the need for integrative studies across life stages to understand the impact of global warming.
迄今为止，有两个有助于更好评估全球变暖生态影响的关键见解尚未得到充分研究：全球变暖对整个生命周期的影响以及热浪的影响。我们测试了在幼虫阶段经历的模拟轻度（25°C）和重度（30°C）热浪对豆娘（Ischnura elegans）飞行能力的影响。为了从机制上理解热应激如何转化为变态后飞行能力的降低，我们评估了与成虫大小相关的性状的假设中介作用，并测试了通过翅形变化和两个与飞行相关的性状（相对脂肪和飞行肌肉含量）起作用的替代途径。暴露于热浪，尤其是严重的热浪，会缩短幼虫阶段，降低与成虫大小相关的性状并改变翅形，但不会显著影响羽化成功率、相对脂肪含量和相对飞行肌肉质量。值得注意的是，热浪对飞行能力的所有组成部分都有负面影响。出乎意料的是，热浪并没有通过减小体型来降低飞行能力。相反，我们发现了一种新的与体型无关的机制，该机制在变态过程中建立联系，将幼虫环境与雄性成虫的飞行能力联系起来：通过影响翅形。本研究推进了对变态过程中仍未充分理解的生命阶段耦合的机制性见解。此外，我们的结果强调了需要进行跨生命阶段的综合研究，以了解全球变暖的影响。
