Data from: Cockroaches that exchange respiratory gases discontinuously survive food and water restriction

Metabolic rate and respiratory gas exchange patterns vary significantly both between and within species, even after a number of biotic and abiotic factors are taken into account. This suggests that such variation is of evolutionary importance, but the life history implications of this variation remain relatively poorly characterised. In the present study we examine the effect of metabolic variation on starvation and desiccation resistance in the speckled cockroach Nauphoeta cinerea. We also compare the starvation and desiccation resistance of individuals that exchange respiratory gases continuously with those that breathe discontinuously. We show that metabolic rate has no effect on survival during food and water restriction, but cockroaches exhibiting discontinuous gas exchange cycles (DGCs) live longer than those that do not and those provisioned with water lived longer than those that were not. This finding represents the first demonstration that DGCs confer a fitness benefit, and supports the oldest hypothesis for the evolution of DGCs (which suggests that DGCs arose or are maintained to reduce respiratory water loss) as we also reveal reduced water loss (both respiratory and total) in cockroaches exhibiting discontinuous gas exchange.

代谢速率与呼吸气体交换模式在物种间及物种内部均存在显著差异，即便在控制了诸多生物与非生物因素后依然如此。这表明此类变异具有进化层面的重要性，但该变异对生物生活史的影响目前仍相对缺乏系统表征。本研究以斑灰蠊（Nauphoeta cinerea）为研究对象，探讨代谢变异对其饥饿抗性与干燥抗性的影响。此外，本研究还比较了持续进行呼吸气体交换的个体与呼吸模式不连续的个体之间的饥饿抗性与干燥抗性差异。研究结果表明，代谢速率对食物与水分限制条件下的存活时长无显著影响，但表现出不连续气体交换循环（discontinuous gas exchange cycles, DGCs）的斑灰蠊存活时长显著长于不具备该特征的个体；同时，获得水分供给的个体存活时长亦显著长于未获得水分供给的个体。本研究结果首次证实DGCs可带来适合度收益，同时支持了关于DGCs演化的经典假说——该假说认为DGCs的起源或维持是为了减少呼吸性水分流失——本研究同时发现，表现出不连续气体交换的斑灰蠊的水分流失（包括呼吸性流失与总水分流失）均显著降低。