Collaborative Research: An Integrative Field and Biophysical Model of Thermal Stress, Physiological Performance, and Reproductive Fitness

动物在它们的地理范围内经历极端的热应激。气候变化可能会加剧这种压力，特别是当地理范围延伸到很大的纬度范围时。许多物种利用行为体温调节来缓解热应激。然而，这些补偿行为是有代价的，因为它们要求动物放弃可能只在炎热和压力大的栖息地进行的关键行为。这项研究调查了在热带和温带地区占据海岸线的小型半陆生螃蟹--招潮蟹的生存/繁殖权衡。雄性招潮蟹在炎热干燥的潮间带使用视觉展示来吸引配偶，但必须定期撤退到凉爽潮湿的洞穴中，以补充水分和恢复体力。每次退回洞穴都需要停止交配行为。雄鱼会定期从炎热的繁殖区重新觅食，以补充水分和进食。这项研究将使用实验和建模方法，在当前和预测的未来条件下，确定物种地理范围内体温调节和交配性能之间的权衡。最后，该项目将利用对招潮蟹的研究成果，通过公共宣传活动和对包括高中生在内的不同层次的学生进行培训，提高公众对科学的兴趣。热应激的行为补偿可能会导致一种深刻但未被充分研究的权衡，因为温度调节行为的成本很高。能量和体温调节成本将产生重大的生殖机会成本，这可能会降低交配成功率。这个项目的重点是与体温调节行为相关的错失交配机会的健康后果。在生理压力和不同纬度的成本差异背景下研究交配成功时，这些错失的机会是至关重要的。了解适合度的相关降低对于充分了解和预测气候变化对适合度的影响至关重要，因为由于热应激成本的增加，较低纬度的供暖可能会缩短交配的好处。这项建议采取综合方法，结合实验室测量、操纵性现场实验和生物物理模型来检查行为体温调节的适宜性后果。这项工作和由此产生的模型将广泛适用于气候变化对地表温度影响的研究。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Animals experience thermal stress at the extremes of their geographic range. This stress may be compounded by climate change, especially when the geographic range stretches over a large range of latitude. Many species use behavioral thermoregulation to ameliorate heat stress. However, these compensatory behaviors have a cost, as they require the animal to abandon critical behaviors that may only be performed in the hot and stressful habitat. This study investigates these survival/reproductive tradeoffs in fiddler crabs, small semi-terrestrial crabs that occupy shorelines in the tropics and temperate zones. Male fiddler crabs use visual displays to attract mates in the hot, dry intertidal zone, but must periodically retreat to a cool, moist burrow to rehydrate and recover. Each retreat to a burrow requires a cessation of mating behavior. Periodically the males rereat from the hot reproductive areas to rehydrate and feed. This study will determine the tradeoff between thermoregulation and mating performance across a species' geographic range, using both experimental and modeling approaches, under both current and predicted future conditions. Finally, the project will utilize the results of the research on fiddler crabs to increase public interest in science using public outreach activities and the training students at different levels including high school students. Behavioral compensation for thermal stress can lead to a profound but under-investigated tradeoff, as thermoregulatory behaviors are costly. Energetic and thermoregulation costs will generate major reproductive opportunity costs, which can reduce mating success. This project focuses on the fitness consequences of missed mating opportunities associated with thermoregulatory behaviors. These missed opportunities are crucial to understand in the study of mating success in the context of physiological stress and the differences in costs at different latitudes. Understanding the associated reductions in fitness are crucial to fully understand and predict the consequences of climate change on fitness, since heating in lower latitudes may truncate the benefit of mating owing to the increased cost of thermal stress. This proposal takes an integrative approach, combining laboratory measurements, manipulative field experiments, and biophysical modeling to examine the fitness consequences of behavioral thermoregulation. This work, and the resulting model, will be broadly applicable to the study of climate change impacts on ectotherms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.