Collaborative Research: Energetic consequences of rain and nest structure for ecology and evolution of songbirds in tropical rainforests

降雨在不同的生物群落之间变化很大，随着时间的推移，也随着厄尔尼诺Niño等天气周期而变化。实验室研究表明，温血生物在潮湿时损失热量的速度更快，必须花费更多的能量来调节体温。降雨对野外能量消耗的影响尚未研究，但可能严重影响生物的繁殖和生存。当动物试图养育后代时，能量通常是最有限的，因为后者的皮毛或羽毛发育不全，因此特别容易受到湿润所增加的能量消耗的影响。本项目研究降雨对热带鸣禽父母及其后代的能量消耗。热带生物提供了一个重要的测试，因为它们被认为对热损失和热条件很敏感，因为热带地区的温度变化很小。此外，雨是热带雨林的普遍特征（通常每年2米）。调查将检查父母和后代在干燥和潮湿的日子里的能量消耗，以及在实验上改变降雨量的巢穴里。将对不同物种进行测量，这些物种在其行为、筑巢类型和潜在的降雨暴露方面存在差异，以促进对降雨变化导致的物种能量成本和不同种群脆弱性的理解。这项工作具有重要的保护意义，因为它确定了生物多样性热点地区特有物种的种群敏感性。此外，许多来自不同学科的学生，包括生物学以外的学生，将接受实地工作和科学原理方面的培训。降水对生态和进化的影响研究甚少。拟议的工作将大大促进对热带雨林中共存鸣禽的降雨变化的能量（野外代谢率）和人口统计学后果的理解。这些代价可能在热带雨林中得到强烈体现，那里雨水普遍，热耐受性较窄，温度往往低于热中性水平。然而，降雨和湿润对不同热带物种能量学、行为和人口统计学影响的研究还很缺乏。提出的工作将使用新的实验和观察方法来推进对巢结构如何影响父母在潮湿和干燥条件下由于热量损失的能量使用的理解。这项工作还将阐明降雨、温度、巢结构和亲代行为如何共同影响后代的能量消耗，以及在生长过程中能量如何分配给不同的身体部位。最后，它将揭示降雨和巢结构的生理成本的人口统计学影响，以获得对健康后果的新见解。最终，本研究将对不同物种间气候和巢结构对热平衡、亲本进化和生长策略的影响提供新的认识。这项工作还将确定物种的相对人口敏感性，作为其巢穴类型，生态和行为的功能，以帮助优先保护计划。大批本科生和研究生以及博士后学者将接受不同领域方法和科学原理的培训。

Rainfall varies extensively among biomes and over time with weather cycles like El Niño. Lab studies have shown that warm-blooded organisms lose heat at a more rapid rate when wet and must spend more energy to regulate body temperature. Effects of rainfall on energy expenditure in the wild is unstudied, but may critically affect reproduction and survival of organisms. Energy is often most limited to animals when trying to raise offspring, with the latter especially vulnerable to increased energy costs of wetting because of poorly developed fur or feathers. This project examines energy costs of rainfall to parents and their offspring in tropical songbirds. Tropical organisms provide an important test because they are thought to be sensitive to heat loss and thermal conditions due to the narrow temperature variation in the tropics. Also, rain is a prevalent feature in tropical rain forests (often 2 m per year). Investigations will examine energy expenditure of both parents and offspring on dry versus wet days and at nests where rainfall is experimentally modified. Measurements will be conducted across diverse species that differ in their behaviors, nest types and potential exposure to rain to advance understanding of the energetic costs and differential population vulnerabilities of species as a result of variation in rainfall. This work has important conservation implications because it identifies population sensitivities of endemic species in a biodiversity hotspot. In addition, many students from a variety of disciplines, including those outside of biology will be trained in the conduct of field work and scientific principles. Ecological and evolutionary influences of precipitation are poorly studied. Proposed work will significantly advance understanding of the energetic (field metabolic rates) and demographic consequences of variation in rainfall on coexisting songbirds in a tropical rainforest. These costs may be strongly expressed in tropical rainforests where rain is prevalent, thermal tolerances are narrow, and temperatures are often below thermoneutral levels. Yet, studies of the effects of rainfall and wetting on energetics, behavior and demography across diverse tropical species are lacking. The proposed work will use novel experimental and observational approaches to advance understanding of how nest structure affects energy use of parents due to heat loss under wet versus dry conditions. The proposed work will also elucidate how rain, temperature, nest structure, and parental behavior combine to affect energy expenditure of offspring and how energy is allocated to differing body components during growth. Finally, it will reveal demographic ramifications of the physiological costs of rain and nest structure to gain new insight into fitness consequences. Ultimately, this work will provide a new understanding of the influences of climate and nest structure upon heat balance and evolution of parental and growth strategies among diverse species. This work will also identify relative demographic sensitivities of species as a function of their nest types, ecologies and behaviors to aid prioritization schemes for conservation. A large number of undergraduate and graduate students, as well as a post-doctoral scholar, will receive training in diverse field methodologies and scientific principles.