The adaptive significance of adjusting behavioral activities to the right time of the day seems obvious. Laboratory studies implicated an important role of circadian clocks in behavioral timing and rhythmicity. Yet, recent studies on clock-mutant animals questioned this importance under more naturalistic settings, as various clock mutants showed nearly normal diel activity rhythms under seminatural zeitgeber conditions. We here report evidence that proper timing of eclosion, a vital behavior of the fruit fly Drosophila melanogaster, requires a functional molecular clock under quasi-natural conditions. In contrast to wild-type flies, period⁰¹ mutants with a defective molecular clock showed impaired rhythmicity and gating in a temperate environment even in the presence of a full complement of abiotic zeitgebers. Although period⁰¹ mutants still eclosed during a certain time window during the day, this time window was much broader and loosely defined, and rhythmicity was lower or lost as classified by various statistical measures. Moreover, peak eclosion time became more susceptible to variable day-to-day changes of light. In contrast, flies with impaired peptidergic interclock signaling (Pdf⁰¹ and han⁵³⁰⁴ PDF receptor mutants) eclosed mostly rhythmically with normal gate sizes, similar to wild-type controls. Our results suggest that the presence of natural zeitgebers is not sufficient, and a functional molecular clock is required to induce stable temporal eclosion patterns in flies under temperate conditions with considerable day-to-day variation in light intensity and temperature. Temperate zeitgebers are, however, sufficient to functionally rescue a loss of PDF-mediated clock-internal and -output signaling

将行为活动调整到一天中的正确时间的适应性意义似乎很明显。实验室研究表明，生物钟在行为计时和节律中起着重要作用。然而，最近对时钟突变动物的研究在更自然的环境下质疑了这一重要性，因为在半自然的时代条件下，各种时钟突变体显示出几乎正常的昼夜活动节律。我们在这里报告的证据表明，羽化的适当时机是黑腹果蝇的重要行为，需要准自然条件下的功能性分子钟。相较于野生型果蝇，期限⁰¹具有缺陷分子钟的突变体在温带环境中表现出节律性和门控受损，即使存在完整的非生物时代。虽然期间⁰¹突变体仍然在白天一定时间窗口期间eclosed，这个时间窗口是更广泛，松散定义，和节律性较低或分类的各种统计措施丢失。此外，羽化高峰时间变得更容易受到日复一日的光照变化的影响。相比之下，肽能时钟间信号传递受损的果蝇（Pdf ⁰¹和han ⁵³⁰⁴PDF 受体突变体）大多以正常门大小有节奏地关闭，类似于野生型对照。我们的研究结果表明，自然时代的存在是不够的，需要一个功能性的分子钟来在光照强度和温度每天都有相当大的变化的温带条件下诱导果蝇稳定的时间羽化模式。然而，温和的时代足以在功能上挽救 PDF 介导的时钟内部和输出信号的丢失