Collaborative Research: Evolving thicker skin: Understanding how adaptations to a universal trade-off dictate the climate vulnerability and ecology of an imperiled vertebrate clade

气候变化正将许多生物推向极限，迫使物种迁移、进化或面临灭绝的风险。青蛙是地球上最脆弱的物种之一，大约三分之一的物种已经面临灭绝的威胁。青蛙和其他两栖动物可以通过皮肤呼吸。然而，它们的渗透性皮肤使青蛙对温度和湿度的变化很敏感，这是我们对气候变化的预期。因此，了解青蛙的皮肤是了解青蛙如何应对气候变化的关键。然而，我们对无尾猿皮肤进化的了解却出奇地匮乏。该项目旨在测量皮肤形态和渗透性的变化，并确定皮肤变化如何影响关键的生存特征，如呼吸和避免脱水的能力。我们的建议通过将生物生理学纳入气候脆弱性的预测，同时扩大我们对严重濒危动物群体的了解，实现了生态学的一个主要目标。此外，青蛙的“皮肤呼吸”提供了一个框架来交流复杂的主题，从进化（例如，趋同和适应）到生理学（例如，氧气转移和水分流失）到保护（例如，气候变化）。该项目将：1)指导USU的美国原住民学生和ISU历史上被排斥的学生进行研究；2)创建一个低成本、互动性和可公开访问的青蛙皮肤活动，重点关注基于探究和发现的进化概念学习。我们的提案旨在了解在濒危脊椎动物分支中，气体交换的普遍约束如何决定气候脆弱性和生态。平衡气体交换的需要和脱水的风险在整个生命树上创造了可预测的进化权衡，并选择了将气体交换与水分流失分离的适应（例如哺乳动物和鸟类独特的鼻子形态，植物的气孔密度和大小）。尽管我们了解了这些进化枝特异性适应在干旱环境中促进生命的作用，但我们对普遍结构的进化知之甚少，比如皮肤。由于它们几乎分布在世界各地，并且依赖于它们的皮肤进行气体交换，我们将无头蜥蜴作为一个理想的系统来研究皮肤如何进化以平衡氧气摄取和水分流失，以应对不同的环境选择压力。该项目有三个目标：1)量化青蛙皮肤在过去2亿年里是如何进化的，以及对非生物和生物因素的反应；2)实验测试蛙类皮肤对呼吸和水分流失的解耦能力；3)将生理数据纳入活动预算模型，以提高我们对当前蛙类分布和生活史进化的理解，并预测物种对未来气候变化的脆弱性。我们将形态学、生理学和建模结合起来，将皮肤形态和生理学与无尾猿生态学和生物地理学联系起来，以提高我们对无尾猿分布、生活史进化和物种对未来气候变化的脆弱性的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Climate change is pushing many organisms towards their limits, forcing species to move, evolve, or risk extinction. Frogs are among the most vulnerable species on the planet with roughly a third already under threat of extinction. Frogs, and other amphibians, can breathe across their skin. However, their permeable skin leaves frogs sensitive to changes in temperature and humidity, which we expect with climate change. Thus, understanding frog skin is key to understanding how frogs will react to climate change. Yet, our knowledge of anuran skin evolution is surprisingly lacking. This project aims to measure variation in skin form and permeability and determine how skin variation affects key survival traits, like their ability to breathe and avoid dehydration. Our proposal accomplishes a major goal in ecology by incorporating organismal physiology into predictions of climate vulnerability while simultaneously expanding our knowledge of a critically threatened animal group. Furthermore, frog “skin breathing” provides a framework to communicate complex topics ranging from evolution (e.g., convergence and adaptation) to physiology (e.g., oxygen transfer and water loss) to conservation (e.g., climate change). This project will: 1) mentor Native American students at USU and historically excluded students at ISU in research and 2) generate a low-cost, interactive, and publicly accessible frog skin activity focused on inquiry and discovery-based learning of evolutionary concepts.Our proposal seeks to understand how a universal constraint underlying gas exchange dictates climate vulnerability and ecology in an imperiled vertebrate clade. Balancing the need for gas exchange with the risk of dehydration creates predictable evolutionary trade-offs across the tree of life and has selected for adaptations that decouple gas exchange from water loss (e.g. unique nasal morphologies in mammals and birds, stomata density and size in plants). Despite understanding the role of these clade-specific adaptations for promoting life in xeric environments, we know relatively little about the evolution of universal structures, such as skin. With their nearly worldwide distribution and reliance on their skin for gas exchange, we use anurans as an ideal system to investigate how skin has evolved to balance oxygen uptake and water loss in response to varying environmental selection pressures. The proposed project has three aims: 1) quantify how frog skin has evolved over the past 200 million years and in-response to what abiotic and biotic factors, 2) experimentally test anuran skin’s ability to decouple respiration and water loss, and 3) incorporate physiological data into activity budget models to improve our understanding of current anuran distributions and life-history evolution and predict species’ vulnerability to future climate change. Our integration of morphology, physiology, and modeling will tie skin form and physiology to anuran ecology and biogeography to improve our understanding of anuran distributions, life-history evolution, and species’ vulnerability to future climate change.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.