For insect species in temperate environments, seasonal timing is often governed by the regulation of diapause, a complex developmental programme that allows insects to weather unfavourable conditions and synchronize their life cycles with available resources. Diapause development consists of a series of distinct phases including initiation, maintenance, termination and post‐diapause development. The evolution of insect seasonal timing depends in part on how these phases of diapause development and post‐diapause development interact to affect variation in phenology. Here, we dissect the physiological basis of a recently evolved phenological shift in Rhagoletis pomonella (Diptera: Tephritidae), a model system for ecological divergence. A recently derived population of R. pomonella shifted from specializing on native hawthorn fruit to earlier fruiting introduced apples, resulting in a 3–4 week shift in adult emergence timing. We tracked metabolic rates of individual flies across post‐winter development to test which phases of development may act either independently or in combination to contribute to this recently evolved divergence in timing. Apple and hawthorn flies differed in a number of facets of their post‐winter developmental trajectories. However, divergent adaptation in adult emergence phenology in these flies was due almost entirely to the end of the pupal diapause maintenance phase, with post‐diapause development having a very small effect. The relatively simple underpinnings of variation in adult emergence phenology suggest that further adaptation to seasonal change in these flies for this trait might be largely due to the timing of diapause termination unhindered by strong covariance among different components of post‐diapause development.

中文翻译：

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生态物种形成过程中生活史时间的快速演变是由发育阶段之间的过渡驱动的

对于温带环境中的昆虫物种，季节性时间通常由滞育调节控制，滞育是一种复杂的发育程序，使昆虫能够抵御不利条件，并使它们的生命周期与可用资源同步。滞育发展包括一系列不同的阶段，包括开始、维持、终止和滞育后发展。昆虫季节时间的演变部分取决于滞育发育和滞育后发育的这些阶段如何相互作用以影响物候变化。在这里，我们剖析了最近进化的梨果蝇（双翅目：实蝇科）物候变化的生理基础，这是一种生态分化的模型系统。最近派生的 R 种群。pomonella 从专注于本地山楂果转变为较早结果的引入苹果，导致成虫出现时间发生了 3-4 周的变化。我们跟踪了整个冬季发育过程中个体果蝇的代谢率，以测试哪些发育阶段可能独立或联合作用，导致最近进化的时间差异。苹果和山楂果蝇在冬季后发育轨迹的许多方面都不同。然而，这些果蝇成虫羽化的不同适应几乎完全是由于蛹滞育维持阶段的结束，滞育后发育的影响非常小。