Temperature Compensation in Antarctic Pteropods: An Integrative Approach

极地水域的生命需要生理上的特化来克服反应过程中的热限制。长期存在的代谢冷适应假说提出极地类群相对于温带类群的基础代谢率和活性代谢率上调，这一假说仍然存在争议，并且在分类上仅限于鱼类和底栖无脊椎动物的评估。极地翼足类动物（软体动物：腹足类）是一个数量丰富且代谢活跃的分类群，在运动的生理过程中具有潜在的大量热补偿。本研究将研究两种翼足类动物的代谢冷适应，特别是运动表现的热依赖性。通过比较具有代表性的温带和极地物种，并通过评估运动行为的代谢、生物力学和神经基础可能协调的热补偿，来测试冷适应的假设。拟进行的研究包括三个部分：1)比较极地和温带翼足类姊妹物种的基础代谢率，以及线粒体能量学的比较；2)比较相同翼足类动物的运动生物力学，特别参考温度降低和伴随的粘度增加对运动性能的不同影响；3)比较游泳系统神经元对不同温度的反应，特别参考静息电位、放电阈值、动作电位持续时间和离子通道动力学。极地翼足类动物对温度补偿的总体假设将通过评估对不同水温的代谢、生物力学和神经反应的相似性和联系来检验。这项研究将为翼足类动物提供基本的生理和行为信息，系统地评估翼足类动物在组织水平上的冷适应假说，并更广泛地评估在极地水域生活和移动的许多无脊椎动物分类群的热和运动限制的本质。

Life in polar waters requires physiological specialization to overcome thermal limits on reaction processes. The long-standing hypothesis of metabolic cold adaptation, which proposes upregulation of basal and active metabolic rates in polar taxa relative to temperate-zone counterparts, remains contentious and has been taxonomically limited in evaluation to fish and benthic invertebrates. Polar pteropods (Mollusca: Gastropoda) represent an abundant and metabolically active taxon with potentially substantial thermal compensation of the physiological processes underlying locomotion. This research will examine metabolic cold adaptation in two pteropod taxa, with particular reference to the thermal dependence of locomotor performance. Hypotheses of cold adaptation will be tested by comparing representative temperate zone and polar species and by evaluating possibly coordinated thermal compensation of metabolic, biomechanical and neural underpinnings to locomotor behavior. The proposed research comprises three parts: 1) comparison of basal and metabolic rates of sister pteropod species from polar and temperate zones, together with comparisons of mitochondrial energetics; 2) comparison of locomotor biomechanics for the same pteropod taxa, with particular reference to the differential effects of reduced temperature and concomitantly increased viscosity on locomotor performance and 3) comparison of the responses of swim system neurons to variable temperatures, with particular reference to resting potentials, firing thresholds, action potential durations and ion channel kinetics. The overall hypothesis of temperature compensation in polar pteropods will be tested by evaluating similarities and linkages in metabolic, biomechanical and neural responses to variable water temperature. This research will provide fundamental physiological and behavioral information for this taxon, will systematically evaluate the hypothesis of cold adaptation across organizational levels in pteropods, and more generally will evaluate the nature of thermal and locomotor constraints for the many invertebrate taxa living and moving within polar waters.