Ecophysiological Correlates of Vertebrate Cold Hardiness

PI将研究某些两栖和爬行动物耐寒的生理、生态和进化方面的问题。这项研究将以木蛙和彩龟幼体为模型，研究低等脊椎动物使用的两种耐寒策略：过冷和耐冻。过冷的动物处于亚稳态，体液在远低于冰点的温度下保持液态(未结晶)。耐寒动物通过耐受身体组织的冻结而在零度以下的温度下生存下来。研究将确定环境和生理因素，影响幼体彩绘海龟在霜冻地带的巢中冬眠期间保持过冷的能力。田间和实验室研究将探索水分对抗寒性的影响。一项比较研究将检验来自不同栖息地的几种北方海龟幼体的脱水阻力和过冷能力之间的关系。这项工作将为一些北方海龟在陆地上冬眠的生理和形态适应提供洞察力。生态生理学的研究常常考虑一种特定适应的好处，而不考虑其有害的后果。这个项目将通过调查冰冻和解冻对生物体表现的特定方面的影响来确定耐寒动物所产生的“权衡”。对林蛙的研究将扩大最近发现的冰冻导致的运动能力和繁殖潜力的损害，并提供作为一种适应性冬季生存策略的严谨耐冻性评估。生理研究，包括冷冻和解冻期间完整青蛙的核磁共振成像，旨在确定损伤的根本原因。通过将实地研究和实验室研究相结合，这项研究将提供关于适应的新见解，这些适应不仅促进在零度以下的温度下的生存，而且还影响一些两栖和爬行动物的地理分布。此外，这项工作对应用学科也有意义，如发展冷冻保存哺乳动物器官的方法，以及使用冷冻保存的两栖动物配子进行非原位繁殖和重新引入计划。

The PIs will investigate physiological, ecological, and evolutionary aspects of cold hardiness in certain amphibians and reptiles. This research will use the wood frog and hatchlings of the painted turtle as models to investigate two cold-hardiness strategies employed by lower vertebrates: supercooling and freeze tolerance. Supercooled animals are in a metastable state in which the body fluid remains liquid (uncrystallized) at temperatures well below its freezing point. Freeze-tolerant animals survive exposure to subzero temperatures by tolerating the freezing of their body tissues. Studies will identify environmental and physiological factors influencing the ability of hatchling painted turtles to remain supercooled during hibernation in their nests, which lie within the frost zone. Field and laboratory studies will explore the effects of moisture on cold hardiness. A comparative study will examine the relationship between desiccation resistance and supercooling capacity in hatchlings of several species of northern turtles from diverse habitats. This work will provide insight into the physiological and morphological adaptations permitting some species of northern turtles to hibernate on land. Research in ecological physiology often considers the benefits of a particular adaptation without regard to its deleterious consequences. This project will identify "trade-offs" incurred by freeze-tolerant animals by investigating the impact of freezing and thawing on selected aspects of organismal performance. Studies of the wood frog will expand recent findings of freezing-induced impairment of locomotor performance and reproductive potential, and provide a rigorous evaluation of freeze tolerance as an adaptive, winter-survival strategy. Physiological studies, including NMR imaging of intact frogs during freezing and thawing, are aimed at identifying the underlying cause of the impairment. By integrating field and laboratory studies, this research will provide novel insights concerning adaptations that not only promote survival at subzero temperatures, but also influence the geographic distributions of some amphibians and reptiles. In addition, this work has implications for applied disciplines, such as the development of methods for cryopreserving mammalian organs and the use of cryopreserved gametes from amphibians for ex situ propagation and reintroduction programs.