Evolution of Photoperiodic Time Measurement and the Circadian Clock in Animals: Perspectives from the Pitcher-Plant Mosquito, Wyeomyia smithii

动物的光周期时间测量和生物钟的进化：从猪笼草蚊子的角度来看，与季节变化相适应的生命周期进化是温带生物的一个主要特征。在像北美这样的温带地区，如果没有利用有利季节的能力，没有减轻或避免不利季节的能力，没有及时从一种生活方式转换到另一种生活方式的能力，生命周期就不可能完整。温带植物和动物用来预测和准备季节变化的最突出的转换机制是白天或光周期的长度。光周期反应的进化是入侵物种地理分布的一个主要特征，正如NSF之前对该实验室的资助最近表明的那样，它适应了快速的气候变化。本研究考察了种群内部和种群之间的生理和遗传过程，这些过程最终构成了温带地区大陆尺度上观察到的季节性适应多样性的基础。这项工作的主要目的是测试控制日常活动的“日常”（昼夜节律）时钟与控制季节性活动的“季节”（光周期）计时器之间是否存在必要的因果关系。人类的日常活动包括睡眠-觉醒模式和饥饿周期；生物钟的紊乱是造成“时差”的原因。季节周期包括鸟类的迁徙，哺乳动物的冬眠，以及自然条件下各种动物的休眠和繁殖。日常时钟的遗传基础已经被很好地理解，但对季节性计时器的遗传基础知之甚少，更不用说这两个过程是如何相互关联的了。本提案中的工作将通过采用一组人工选择实验来测试日常计时器和季节性计时器之间联系的遗传灵活性。了解这两种计时机制之间潜在的相互作用，对于理解温带生物如何扩大其活动范围、为休眠和繁殖等多种事件设定时间以及应对气候变化至关重要。北美正在经历一段前所未有的气候变化时期，这一时期强烈的自然选择改变了季节活动的时间。即将进行的实验将显示季节计时器的修改是否以及如何影响日常时钟，反之亦然。了解季节性适应的遗传学基础将有助于评估重要农作物的生存、病媒传播疾病的传播、农业害虫的影响以及自然生物群落的组成。这项研究很适合本科生参与，不仅作为研究助理，而且作为年轻的研究者从事相关但独立的项目。最近从这个实验室毕业的本科生继续读研究生或医学院，从事教师、应用生物学家、律师、记者和其他与科学无关的职业。不管他们未来的努力，这些学生构成了一个知情的公民，更了解基础研究，它的重要性，它的影响。本研究将延续本实验室对本科生研究参与和培训的传统和承诺。

Evolution of Photoperiodic Time Measurement and the Circadian Clock in Animals: Perspectives from the Pitcher-Plant Mosquito, Wyeomyia smithiiWilliam E. BradshawUniversity of Oregon EugeneEvolution of life cycles that are compatible with the changing seasons is a major feature of temperate organisms. No life cycle in a temperate zone like North America can be complete without the ability to exploit the favorable season, the ability to mitigate or avoid the unfavorable season, and the ability to switch from one lifestyle to the other on a timely basis. The most prominent switching mechanism used by temperate plants and animals to anticipate and prepare for the changing seasons is the length of day or photoperiod. Evolution of photoperiodic response is a major feature of the geographic dispersal of invading species and, as prior funding to this lab by NSF has recently shown, adaptation to rapid climate change. This research examines the physiological and genetic processes within and between populations that ultimately constitute the basis for the diversity of seasonal adaptations observed over a continental scale at temperate latitudes. The main objective of this work is to test whether there is a necessary, causal connection between the "daily" (circadian) clock controlling daily activities and the "seasonal" (photoperiodic) timer controlling seasonal activities. Daily activities include sleep-wakefulness patterns and hunger cycles in humans; disruption of the circadian clock is responsible for "jet lag." Seasonal cycles include migration in birds, hibernation in mammals, and dormancy and reproduction in a wide array of animals under natural conditions. The genetic basis of daily clocks is fairly well understood, but little is known about the genetic basis of the seasonal timer, let alone how the two processes relate to each other. The work in this proposal will test for the genetic flexibility of the connection between the daily and the seasonal timer by employing a set of artificial selection experiments. Knowledge of the potential interaction between these two timing mechanisms is fundamental to understanding how temperate organisms expand their ranges, time events as diverse as dormancy and reproduction, and cope with climate change. North America is undergoing a period of unprecedented climate change that is imposing strong natural selection for altering the timing of seasonal activities. The experiments to be run will show whether and how modification of the seasonal timer affects the daily clock and vice versa. Understanding the genetics underlying seasonal adaptation will assist in evaluating the survival of important agricultural crops, the spread of vector-borne diseases, the impact of agricultural pests, and the composition of natural biotic communities. This research lends itself well to undergraduate participation, not just as research assistants, but also as young investigators pursuing related but independent projects. Recent undergraduate students from this lab have continued on to graduate or medical school, to careers as teachers, applied biologists, lawyers, journalists, and to other professions not related to science. Regardless of their future endeavors, these students constitute an informed citizenry, more aware of basic research, its importance, and its implications. This research will continue a strong tradition and commitment to undergraduate research participation and training by this laboratory.