沉积物中古DNA在古生态、古环境和古气候研究中的应用

Applications of ancient DNA preserved in sediment in paleo-ecology,paleo-environment and paleo-climate studies

随着分子生物学技术的发展,DNA技术的应用逐渐从生物学研究拓展到进化、环境和气候变化等研究领域。因为DNA容易受到水解、氧化、紫外辐射、酶解等过程的破坏,所以人们认为DNA很容易降解,保存时间不长,但是近年来的研究成果显示,古生物和古人类的化石或骨骼、冻土、湖泊海洋沉积物等样品中包含已保存数千年甚至长达数百万年以来的古DNA。古DNA作为重要的信息载体,可以诠释人类、动植物和微生物进化和迁移过程及它们对环境和气候变化的响应。反过来,古DNA在古环境、古气候重建方面也起着重要作用,沉积物样品的古DNA往往保存了历史时期的水体和水体周围环境以及气候变化等信息。通过对沉积物中古DNA的研究,可以获得历史时期的水生生物(包括藻类、水生动植物等)的群落演化,和水体周围岸基生活的动植物群落(植物落叶、动物毛发冲带到水体并沉积下来)演替,进而反演水体和水体周围气候环境以及气候变化信息。通过研究古人类和动物化石中保存的DNA,可以探讨人类的迁徙和进化过程,溯源家畜的驯化历史。本文将介绍环境古DNA的保存和可靠性评价,重点探讨古DNA在古生态以及古环境、古气候重建研究中的优势及应用,并展望古DNA在生物进化和环境研究等领域的应用前景。

With the development of techniques in molecular biology,the application of DNA technology is gradually being expanded from traditional biological areas to the studies of evolution,environmental and climatic changes.DNA is vulnerable to various abiotic（hydrolysis,oxydation,UV-damage）and biotic（enzyme damage）degradation processes,and was thought to be not persistent enough in geological samples.However,more and more researches have showed that ancient DNA older than thousands to millions years existed in fossil bones,permafrost,lacustrine and marine sediment samples.As a result,ancient DNA becomes an effective tool to investigate the evolution and migration of human,animals,plants,and even microbes,and their responses to the change of paleo-environment and paleo-climate.In return,ancient DNA also has played an important role in the reconstruction of paleo-environment and paleo-climate.For example,lacustrine sediment might have pooled with ancient DNA both from lake dwelling and catchment dwelling microbes,plants and animals.By sequencing these ancient DNA from sediment,people can catch the sight of regional evolution of microbes,plants and animals over the past time.This review will introduce ancient DNA preservation and its reliability in paleo-environmental and paleo-ecology studies,and will discuss the advantages of this ancient DNA approach in paleo-environmental and climatic reconstruction.We also pointed out a few important applications of the ancient DNA approach in biological evolution and environmental studies.