Chronobiology Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Karnataka, India.
Chronobiol Int. 2012 Jul;29(6):674-82. doi: 10.3109/07420528.2012.680557.
The authors derived early and late populations of fruit flies showing increased incidence of emergence during morning or evening hours by imposing selection for timing of emergence under 12:12 h light/dark (LD) cycles. From previous studies, it was clear that the increased incidence of adult emergence during morning and evening hours in early and late populations was a result of evolution of divergent and characteristic emergence waveforms in these populations. Such characteristic waveforms are henceforth referred to as "evolved emergence waveforms" (EEWs). The early and late populations also evolved different circadian clocks, which is evident from the divergence in their clock period (τ) and photic phase response curve (PRC). Although correlation between emergence waveforms and clock properties suggests functional significance of circadian clocks, τ and PRCs do not satisfactorily explain the early and late emergence phenotypes. In order to understand the functional significance of the PRC for early and late emergence phenotypes, the authors investigated whether circadian clocks of these flies exhibit any difference in photosensitivity under entrained conditions. Such differences would suggest that the light requirement for circadian entrainment of the emergence rhythm in early and late populations is different. To test this, they examined if early and late flies differ in their light utilization behavior, first by assaying their emergence rhythm under complete photoperiod and then in three different skeleton photoperiods. The results showed that early and late populations require different durations of light during the morning and evening to achieve their EEWs, suggesting that for the circadian entrainment of the emergence rhythm, early and late flies utilize light from different parts of the day.
作者通过在 12:12 小时光/暗（LD）周期下对出蜂时间进行选择，得出了出蜂时间较早和较晚的果蝇种群，其出蜂时间在早晨或傍晚的发生率增加。从之前的研究中可以清楚地看出，早期和晚期种群中，成虫出现在早晨和傍晚的发生率增加，是这些种群中出蜂时间出现不同且特征性的波形演变的结果。这种特征性的波形此后被称为“进化的出蜂波形”（EEWs）。早期和晚期种群也进化出了不同的生物钟，这从它们的生物钟周期（τ）和光相反应曲线（PRC）的差异中可以明显看出。尽管出蜂波形和生物钟特性之间存在相关性，暗示了生物钟的功能意义，但 τ 和 PRC 并不能令人满意地解释早期和晚期的出蜂表型。为了了解 PRC 对早期和晚期出蜂表型的功能意义，作者研究了这些果蝇的生物钟在受约束条件下是否表现出任何感光差异。这种差异表明，早期和晚期种群中出蜂节律的生物钟受光的要求是不同的。为了验证这一点，他们检查了早期和晚期果蝇在光利用行为上是否存在差异，首先是在完整光周期下检测它们的出蜂节律，然后在三种不同的骨架光周期下进行检测。结果表明，早期和晚期种群在早晨和傍晚达到 EEWs 时需要不同时长的光照，这表明对于出蜂节律的生物钟同步，早期和晚期果蝇利用了一天中不同时间的光。
