两栖爬行动物的高海拔适应性演化:现状与展望

High-altitude adaptive evolution in amphibians and reptiles:Status and prospect

高海拔极端环境具有低温、低氧、强紫外等特点,加之复杂的地质历史、独特的地形地貌等环境因素,为开展生物适应性演化研究提供了天然实验室.作为变温动物(poikilotherm)的代表类群,两栖爬行动物是高海拔生物区系中重要的组成部分,已知物种最高海拔分布可达5300 m.前期研究显示两栖爬行动物代表物种在生理、形态及生活史等方面进化出一系列表型特征,以适应高海拔环境.近年来,随着新一代测序技术的发展,从基因组水平探讨高海拔适应的分子机制成为可能,并取得了突破性进展,尤其是青藏高原地区代表性两栖爬行动物基因组的解析,标志着两栖爬行动物适应性演化研究进入了一个新的时代.本文总结分析了目前表型研究已取得的成果,重点分析和讨论了分子机制的研究进展.展望未来,以下几个方面研究将是发展的重点:表型组学(phenomics)的建立;表型组和基因组(genomics)的关联分析;遗传变异的功能分析及实验体系的建立.高海拔适应性研究已成为两栖爬行动物适应性演化研究领域的开拓性工作和范例.

The study of high-altitude adaptation is pioneering and exemplary work in the field of adaptive evolution in amphibians and reptiles.High-altitude areas often have extreme environmental characteristics,such as low temperature,hypoxia,and strong ultraviolet(UV)radiation,in addition to a complex geological history and unique topography.Therefore,these areas provide a natural laboratory for examining the adaptive evolution of organisms.As representative groups of poikilotherms,amphibians and reptiles are important members of high-altitude fauna;some of them are found as high as 5300 m above sea level.Previous studies have reported that representative species of high-altitude amphibians and reptiles have evolved a series of phenotypic characteristics in physiology,morphology,and life history to adapt to extreme environments.With the development of next-generation sequencing technology,breakthroughs have recently been made in exploring the molecular mechanisms of high-altitude adaptation at the genomic level.In particular,complete genomes of representative amphibians and reptiles in the Qinghai-Tibet Plateau have been elucidated,leading to a better understanding of poikilotherm adaptive evolution.In this study,we investigated and summarized results of phenotypic studies on high-altitude adaptation in amphibians and reptiles,focusing on the analysis and discussion of molecular mechanisms.We believe that several study fields should,therefore,focus on the(i)establishment of phenomics,(ii)association analysis of phenomics and genomics,(iii)functional analysis of genetic variation,and(iv)establishment of experimental systems.