DISSERTATION RESEARCH: Ecological Correlates of Circadian Organization: Photic Niche and Photosensitivity in Anolis Lizards

生物钟存在于从细菌到人类的几乎所有生物体中，控制着生理和行为的日常节奏，包括熟悉的睡眠-觉醒周期。昼夜循环将生物钟传递给外部世界。光对于昼夜节律的正确定时至关重要，然而生物体生活在不同的光照栖息地，从黑暗的洞穴到阳光普照的大草原。生物钟是如何“正确”地响应这种广泛的光缐的？该项目测试的假设，生物钟已被修改的进化，使他们作出适当的反应，以光水平通常经历了一个物种在其原生栖息地。为了验证这一想法，研究人员将捕捉几种不同种类的变色龙，一种生活在不同光照条件下的加勒比海小型蜥蜴。使用自动行为记录技术，他们将确定行为活动节律如何根据光暗周期的强度而变化。研究人员还将检查松果体，这是一个位于大脑中的小器官，分泌一种称为褪黑激素的激素。松果体是蜥蜴的主生物钟，褪黑激素的产生受光线控制。通过测量光诱导的褪黑激素产生的变化，研究人员可以确定昼夜节律钟的光（光）敏感性。据预测，生活在森林深处的变色龙物种相对于生活在阳光充足的栖息地的物种，对光线对生物钟的影响更为敏感。从保护的角度来看，了解光环境和生物钟之间的进化关系非常重要，因为城市住区的“光污染”会破坏生态系统。该项目将为几名本科生提供研究经验，除了至少一名研究生的博士培训。

Circadian clocks, found in virtually all organisms from bacteria to humans, control daily rhythms in physiology and behavior, including the familiar sleep-wake cycle. The day-night cycle synchronizes the circadian clock to the external world. Light is crucial for the proper timing of circadian rhythms, yet organisms live in diverse light habitats, ranging from dark caves to sun-drenched savannahs. How does the circadian clock respond "correctly" to this broad range of light cues? This project tests the hypothesis that circadian clocks have been modified by evolution such that they respond appropriately to light levels normally experienced by a species in its native habitat. To test this idea, the investigators will capture several different species of anoles, small Caribbean lizards living in diverse light conditions. Using automated behavioral recording techniques, they will determine how behavioral activity rhythms change according to the strength of the light-dark cycle. The investigators will also examine the pineal gland, a small organ located in the brain that secretes a hormone called melatonin. The pineal gland is the master circadian clock in lizards, and melatonin production is controlled by light. By measuring the light-induced changes in melatonin production, the investigators can determine the photic (light) sensitivity of the circadian clock. The prediction is that anole species living in the deep forest will be more sensitive to the effects of light on the circadian clock, relative to species living in sunnier habitats. Understanding the evolutionary relationship between the light environment and circadian clocks is important from a conservation standpoint, as "light pollution" from urban settlements is known to disrupt ecosystems. This project will provide research experience for several undergraduate students, in addition to the doctoral training of at least one graduate student.