高原鼠兔（Ochotona curzoniae)受海拔影响体型进化（贝格曼定律）的选择基础

Animals living in extreme altitudes must cope with very low temperatures and intermittent food supplies. This leads to adaptive evolution of their body size – animals at higher altitudes are larger (Bergmann’s law). The selection pressures that drive such adaptations at high altitude remain unclear. Larger body size may be advantageous at high altitude because it reduces the maximal thermogenic power requirement and increases fasting endurance. In contrast lower body size may be advantageous at lower altitudes because it facilitates heat dissipation and increases reproductive output. We will study which of these processes is most important in the plateau pika (Ochotona curzoniae), a small lagomorph living on the Qinghai-Tibetan plateau. This species is a commercially significant pest species and an ecological keystone species, and this work will contribute to understanding potential future consequences of climate change for this animal. We will examine the scaling relationships between energy expenditure and fat storage to evaluate the fasting endurance hypothesis, by using the doubly-labelled water technique. We will explore the molecular responses to fasting, and examine the molecular basis of the variation in thermogenic capacity in relation to altitude, using analysis of gene expression profiles in brown adipose tissue and skeletal muscle. In addition we will explore the relationship between reproductive productivity and body size in relation to ambient temperature. The strength of this proposal is that it provides the first test of alternative hypotheses for the selection pressures that underpin the adaptive evolution of body size in a wild mammal. This will contribute to China’s international position in the field of evolutionary physiology.

生活在高海拔地区的动物必须应对低温和间断的食物供给，引起体型的适应性进化，即生活在越高海拔的动物体型越大（贝格曼定律）。驱动动物适应高海拔的选择压力尚不明确。在高海拔地区，大体型动物，因最大产热能力需求低，饥饿耐受能力高而更具优势。而在低海拔地区，小体型动物，因热耗散快且繁殖产出高而更具优势。高原鼠兔是生活在青藏高原的小型兔类，是有害种和生态学关键种，本项目中我们将研究高原鼠兔适应性进化的选择压力，首先拟利用双标水技术测定野外条件下的能量消耗和脂肪含量，研究能量消耗和脂肪储存的比例关系，来检验饥饿耐受假说。其次检测褐色脂肪和肌肉组织的基因表达谱来探索海拔引起产热能力差异的分子基础。此外，还将探索环境温度对繁殖力与体型关系的影响。项目将首次验证驱动野生哺乳动物体型适应性进化的选择压力的不同假说，促进我们了解未来气候变化对该物种的潜在影响，也将提升我国在进化生理学研究领域的国际影响力。