RUI: Identifying the physiological mechanisms and potential costs of elevated thermal tolerance from life-history stage-dependent changes in thermal habitat

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。海洋潮间带生物进化出更高的耐热极限，以应对与退潮与热浪重合的时间相关的热应力。气候变化-由于维持更高的耐热性，预计此类事件的频率和严重程度的增加将对这些生物体产生影响。耐热性的提高会带来能量成本，这是热生理学的一个长期假设，但实际成本尚未量化。该项目将比较来自温带和热带潮间带和潮下带栖息地的密切相关瓷蟹物种在生活史阶段(胚胎、幼体浮游、幼体和成年)的耐热性，这些物种经历了最高栖息地温度的较大梯度。在具有不同耐热性的物种中，将检查基础代谢率、新陈代谢和代谢酶的温度敏感性、能量储存和生长速度。由于幼虫是浮游性的，不受潮间带极端温度的影响，因此在温度上与其他阶段不同。幼虫有望避免与提高耐热性相关的生理成本，耐热性最强的物种有望避免幼虫与其他生活史阶段的热耐性的最大差异。根据幼虫和成虫代谢的差异，将量化提高耐热性的实际能量成本。这些成本的量化将有助于评估气候变化增加的热应力将如何影响海洋潮间带无脊椎动物在自然环境中的分布。该项目的更广泛影响包括一年的博士后研究人员教育，两年的MS研究生教育，通过SFSU Breed REU计划招聘的本科生研究助理，以及PI教授的动物生理学实验室课程。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Marine intertidal zone organisms have evolved elevated thermal tolerance limits in response to thermal stress associated with times that low tide coincides with heat waves. Climate-change projected increases in the frequency and severity of such events are hypothesized to have an impact on these organisms due to the energetic expenditure of maintaining elevated heat tolerance. That elevated heat tolerance has an energetic cost is a long-standing assumption in thermal physiology but the actual costs have not been quantified. This project will compare thermal tolerance across life-history stages (embryonic, larval planktonic, juvenile and adult) in species of closely related porcelain crabs from temperate and tropical intertidal and subtidal habitats that experience a wide gradient in maximal habitat temperature. In species with different thermal tolerances, basal metabolic rates, temperature sensitivity of metabolism and metabolic enzymes, energy storage, and growth rates will be examined. Larvae differ in thermal habitat from the other stages since the larvae are planktonic and not subjected to thermal extremes of the intertidal zone. Larvae are expected to avoid the physiological costs associated with elevated thermal tolerance, and the largest difference between larval and other life history stage thermal tolerance is expected in the most heat tolerant species. From the difference between larval and adult metabolism the actual energetic cost of elevated thermal tolerance will be quantified. Quantification of those costs will be useful for assessing how climate change increases in thermal stress will impact energetics of marine intertidal zone invertebrates across their distribution in the natural environment.The broader impacts of this project include education of a postdoctoral researcher for one year, a MS graduate student for two years, and undergraduate research assistants recruited through the SFSU BREED REU program as well as an Animal Physiology Laboratory course taught by the PI.