Data from: Drosophila embryogenesis scales uniformly across temperature in developmentally diverse species

Temperature affects both the timing and outcome of animal development, but the detailed effects of temperature on the progress of early development have been poorly characterized. To determine the impact of temperature on the order and timing of events during Drosophila melanogaster embryogenesis, we used time-lapse imaging to track the progress of embryos from shortly after egg laying through hatching at seven precisely maintained temperatures between 17.5°C and 32.5°C. We employed a combination of automated and manual annotation to determine when 36 milestones occurred in each embryo. D. melanogaster embryogenesis takes 33 hours at 17.5°C, and accelerates with increasing temperature to a low of 16 hours at 27.5°C, above which embryogenesis slows slightly. Remarkably, while the total time of embryogenesis varies over two fold, the relative timing of events from cellularization through hatching is constant across temperatures. To further explore the relationship between temperature and embryogenesis, we expanded our analysis to cover ten additional Drosophila species of varying climatic origins. Six of these species, like D. melanogaster, are of tropical origin, and embryogenesis time at different temperatures was similar for them all. D. mojavensis, a sub-tropical fly, develops slower than the tropical species at lower temperatures, while D. virilis, a temperate fly, exhibits slower development at all temperatures. The alpine sister species D. persimilis and D. pseudoobscura develop as rapidly as tropical flies at cooler temperatures, but exhibit diminished acceleration above 22.5°C and have drastically slowed development by 30°C. Despite ranging from 13 hours for D. erecta at 30°C to 46 hours for D. virilis at 17.5°C, the relative timing of events from cellularization through hatching is constant across all species and temperatures examined here, suggesting the existence of a previously unrecognized timer controlling the progress of embryogenesis that has been tuned by natural selection as each species diverges.

温度可影响动物发育的时序与最终结果，但目前学界对温度在早期发育进程中的具体调控作用仍缺乏充分解析。为探明温度对黑腹果蝇（Drosophila melanogaster）胚胎发育各事件的时序与发生顺序的影响，我们采用延时成像技术，在17.5℃至32.5℃间7个精准控制的温度条件下，追踪了果蝇胚胎从产卵后不久直至孵化的整个发育进程。我们结合自动与手动注释方法，确定了每枚胚胎中36个发育里程碑的发生时间。黑腹果蝇的胚胎发育在17.5℃下需耗时33小时，随温度升高发育速率逐步加快，在27.5℃时最短仅需16小时；当温度高于27.5℃后，胚胎发育速率会出现小幅回落。值得注意的是，尽管胚胎发育总时长差异可达两倍之多，但从细胞化阶段直至孵化的各事件相对时序，在不同温度条件下均保持恒定。为进一步探究温度与胚胎发育的关联，我们将分析范围拓展至另外10种具有不同气候起源的果蝇物种。其中6个物种与黑腹果蝇一样，均为热带起源，它们在不同温度下的胚胎发育时长模式高度相似。莫哈韦果蝇（D. mojavensis）作为亚热带果蝇，在低温环境下的发育速率慢于热带果蝇物种；而维氏果蝇（D. virilis）作为温带果蝇，在所有温度条件下均表现出更慢的发育速度。作为近缘高山物种的拟暗果蝇（D. persimilis）与伪暗果蝇（D. pseudoobscura），在低温环境下的发育速率与热带果蝇相当，但在22.5℃以上时发育速率的提升幅度会显著降低，当温度达到30℃时发育速率会大幅放缓。尽管本次研究涉及的物种中，30℃下直立果蝇（D. erecta）的胚胎发育仅需13小时，而17.5℃下维氏果蝇的发育时长可达46小时，但所有受试物种在所有温度条件下，从细胞化阶段至孵化的各事件相对时序均保持一致。这一结果提示，存在一种此前未被发现的胚胎发育进程调控计时器，且该计时器随物种分化经历了自然选择的适应性调控。