It is a common notion that phases-of-entrainment of circadian rhythms are adaptive, in that they enable organisms to time their behavior to specific times of the day to enhance their fitness. Therefore, understanding mechanisms that bring about such phases-of-entrainment is crucial to chronobiologists. Our previous studies have shown that selection for morning and evening phasing of adult emergence in Drosophila melanogaster populations leads to divergent coevolution of free-running periods of both adult emergence and activity/rest rhythms, such that early (morning) and late (evening) adult emergence chronotypes have shorter and longer circadian periods, respectively. However, there is little evidence to support the notion that phases-of-entrainment in these fly stocks is indeed driven by non-parametric mechanisms. Extending from a previous hypothesis based on anecdotal evidence for parametric mechanisms being in play, we explore the extent of non-parametric and parametric effects of light on circadian clocks of early and late chronotypes. We systematically tested predictions of the non-parametric model of entrainment, sketched the Circadian Integrated Response Characteristic (CIRC) of our stocks, assessed the effect of light pulses on amplitude of the behavior and the effect of duration of light pulse on phase-shifts of the clock. We demonstrate that, in addition to the differences in clock period, divergent CIRCs contribute to entrainment of the activity/rest rhythm. The differences in CIRC could be explained by differential transient amplitude responses and duration responses of the clock’s phase between the early and late chronotypes. Our study thus highlights the role of amplitude responses and phase-shifts due to long durations of light in entrainment of circadian rhythms of D. melanogaster.

通常的观点是，昼夜节律的发作阶段是适应性的，因为它们使生物能够将其行为定时到一天中的特定时间以增强其适应性。因此，了解导致这种夹带阶段的机制对于计时生物学家至关重要。我们以前的研究表明，在果蝇果蝇种群中选择早，晚成年成虫会导致成年和活动/休息节律的自由奔放时期的协同进化，例如早（早）和晚（晚上）成人出现的时间型分别具有较短和较长的昼夜节律。但是，几乎没有证据支持这种观点，即这些蝇类的夹带阶段确实是由非参数机制驱动的。从先前基于参数机制起作用的轶事假设出发，我们探索了光对早期和晚期生物钟的非参数和参数影响的程度表型。我们系统地测试了非参数夹带模型的预测，勾画了我们股票的昼夜节律综合响应特征（CIRC），评估了光脉冲对行为振幅的影响以及光脉冲持续时间对相变的影响。时钟。我们证明，除了时钟周期的差异之外，不同的CIRC也会导致活动/休息节奏的train带。CIRC的差异可以用早期和晚期表型之间时钟相位的差分瞬态幅度响应和持续时间响应来解释。因此，我们的研究强调了由于光的持续时间长而引起的幅度响应和相移在夹带昼夜节律中的作用。D.黑变种。