Collaborative Research: RUI: Transduction of Physiological Stress through Species Interactions: Indirect Effects of Climate Change

由于大气中温室气体浓度的增加，陆地和海洋的温度正在上升。到目前为止，许多研究都集中在气温上升对动物的直接生理影响上。然而，一个受到较少关注的重要领域是了解物种之间的相互作用将如何因气候变暖而改变。这个项目试图描述一个易受气候变化影响的物种所经历的生理压力通过行为相互作用传递给另一个物种的程度，即使第二个物种本身不容易受到气候变化的影响。这项拟议的研究将揭示气候变化对生理健康的多方面性质，这是所有野生动物面临的一个重要问题，包括濒危和重要的经济物种。本科生和研究生将参与到这项工作的各个方面，接受重要的科学培训。此外，研究人员正在与中学教师合作开发关于气候变化和海洋生物的教育模块，并将邀请学校教室到实地观察和参与科学研究。这项研究将在一个热生物学模型系统中评估生理和物种相互作用对气候变化的反应：一对同域潮间带瓷蟹物种(石油蟹属)，它们对气候变化的直接敏感性不同。这两个物种共同生活在多岩石的太平洋海岸，但一个物种生活在较温暖的中潮间带，另一个物种生活在较凉爽的低潮间带和潮下带。中潮间带物种(竞争优势种)比低潮间带物种(竞争从属种)对温度升高更敏感，这是由于每种物种的热性能和它们所经历的最高栖息地温度。这项研究的中心假设是，气温上升可能会迫使潮中带物种进入低潮间带栖息地，增加竞争相互作用，并导致低潮间带物种行为压力增加。这一假设将在对自然栖息地中的螃蟹的三项研究中得到验证，一项人工现场实验和一项实验室实验：(1)将测量自然环境中螃蟹的热条件和分布，以确定温暖条件在多大程度上增加了物种共存和竞争相互作用的可能性。(2)对两个潮间带高度笼养的蟹进行了现场操作实验，以测定其对温度应激的行为反应。温度的变化将由放置在笼子上的人造石头的厚度和组成来调节，否则情况将自然变化。(3)利用潮间带模拟实验水槽测试各蟹种对温度胁迫的行为和生理反应。加热灯将被用来调节不同浸泡程度的石头下的温度。在野外(2)和实验室(3)实验中，将对蟹类进行单独和组合测试。所有三项研究中的生理状况都将从血淋巴(血液)样本中利用现有的基因表达、热应激生物标记物和生殖活动的卵黄蛋白分析进行评估。44个目标转录本和6个看家基因的基因表达水平将使用NanoStringnCounter平台进行评估，这是一种基于非扩增的直接mRNA测量方法。对来自卵母细胞的卵黄蛋白(卵黄蛋白)和来自血淋巴的卵黄蛋白前体(卵黄蛋白原)的检测将使用基于抗体的分析(ELISA法)。

Temperatures on land and in the ocean are rising as a result of increased greenhouse gas concentrations in the atmosphere. Much research to date has focused on the direct physiological influence of rising temperatures on animals. However, an important area that has received less attention is to understand how species interactions will change as a result of warming. This project seeks to characterize the degree to which physiological stresses experienced by one species that is vulnerable to climate change are transduced to a second species through behavioral interactions, even if that second species is not itself vulnerable to climate change. The proposed research will uncover the multifaceted nature of climate change on physiological health, an important problem for all wildlife, including endangered and economically important species. Undergraduate and graduate students will be involved in all aspects of this work, receiving important scientific training. In addition, the researchers are teaming with secondary school teachers to develop educational modules on climate change and ocean life, and school classrooms will be invited to field sites to observe and participate in scientific research. This research will assess physiological and species interaction responses to climate change in a model system for thermal biology: a pair of sympatric intertidal zone porcelain crab species (genus Petrolisthes) that differ in their direct susceptibility to climate change. Both species occur together on rocky Pacific shores but one species lives in the warmer mid-intertidal zone and the other in the cooler low-intertidal and subtidal zones. The mid-intertidal species (the competitive dominant) is more sensitive to rising temperatures than the low-intertidal species (the competitive subordinate) due to the thermal performance of each species and the maximal habitat temperatures they experience. The central hypothesis of the study is that rising temperatures will likely force the mid-intertidal species into the low-intertidal habitat, increasing competitive interactions and causing increased behavioral stress to the low-intertidal species. That hypothesis will be tested in three studies of crabs in the natural habitat, a manipulated field experiment, and a laboratory experiment: (1) Thermal conditions and distributions of crabs will be measured in their natural environments to determine the degree to which warm conditions increase species co-occurrence and the potential for competitive interactions. (2) A manipulative field experiment will be conducted to measure behavioral responses to thermal stress in crabs caged at two intertidal heights. Temperature variation will be regulated by thickness and composition of artificial stones placed over caged crabs, else conditions will vary naturally. (3) Experimental intertidal zone simulation tanks will be used to test for behavioral and physiological responses of each crab species to thermal stress. Heat lamps will be used to regulate temperatures under stones with differing degrees of immersion. In field (2) and laboratory (3) experiments, crab species will be tested separately and in combination. Physiological condition in all three studies will be assessed from hemolymph (blood) samples using existing gene expression thermal stress biomarkers and yolk protein assays of reproductive activity. Gene expression levels of 44 target transcripts and 6 houskeeping genes will be estimated using the NanoString nCounter platform, a non-amplification based direct measurement of mRNA. Assays of yolk protein (vitellin) from oocytes and yolk protein precursor (vitellogenin) from hemolymph will be performed using antibody-based assays (ELISA) with available antibodies.