摘要
冰期 (尤其是更新世冰期 )对当今生物的空间分布格局和遗传结构产生了深远影响 ,研究生物冰期避难所对于了解不同生物区系间的关系、物种形成以及生物多样性保护具有十分重要的意义。生物冰期避难所的确定最初是根据特有种的分布、化石、孢粉等证据推测而来 ,分子遗传标记为冰期生物避难所以及冰期后重新扩散路线的研究提供了有力的工具。本文以北美和欧洲为例 ,介绍了分子遗传标记在生物避难所以及冰期后再扩散路线研究中的应用和一些结论。我国存在许多东西走向的大山 ,减缓了冰期时低温对生物的影响 ,为许多生物提供了避难场所 ,但我国有关研究开展得很少。最后 ,对我国该领域提出了应优先开展的研究方向。
Glaciations especially the Pleistocene glaciations have important effects on the patterns of spatial distribution and genetic structure of organisms. Glacial refugium is the area where plants and animals could survive the severity climate and physical condition during glaciations, in particular the last glaciation. Studies on the glacial refugia and postglacial recolonization patterns can help reveal the relationship of different flora and fauna, understand speciation, and improve biodiversity conservation. In recent years, there are increasing interests on the glacial refugia because of the following reasons: First, glacial refugium is the source of postglacial redistribution, so studying glacial refugia and postglacial recolonization pattern can help to reveal the history and structure of different populations. Secondly, isolation between glacial refugia provides a very important mechanism leading to the development of new species or subspecies (speciation). Finally, glacial refugia are usually key regions for long\|term maintenance of biodiversity and sites needing prior conservation because of their abundant biodiversity. Usually, glacial refugia are identified according to the endemism of flora and fauna based on the hypothesis that isolation between glacial refugia will lead to speciation especially with low recolonization ability. It is also obtained from some other indirect evidences, such as palynology, paleoclimatology, palaeobotany and fossils. Recently, molecular markers, in particular SSR, RFLP (or PCR\|RFLP) and allozyme markers, have proved powerful in identifying the refugium and tracking the colonization route. More organelle genome (mtDNA and cpDNA) markers are used because the organelle genome is in maternal or paternal inheritance without recombination while nuclear markers are too complex and are affected by too many factors. As a consequence the initial geographical structure is probably retained longer for organelle genome than for nuclear genome markers. At present, studies on glacial refugium and postglacial recolonization using molecular genetic markers are mostly focus on the species of Northern America and Europe. Many studies revealed that the Bering Sea region, high\|altitude zone of North Pole, the southern Appalachian Mountains and the southern Rocks Range are the main refugia for flora and fauna of North America. Poke milkweed (Asclepias exaltata), Dryas integrifolia, Microtus longicawdus , and Arctic grayling (Thymallus arcticus) are the species representing four types of glacial refugia and recolonization routes in Northern America. In Europe, the three southern peninsulas, i.e. Iberian, Italion and Balkan, are three important refugia for terrestrial flora and fauna during Pleistocene glaciation. Three broad patterns are evident for terrestrial species in Europe, and the grasshoper (Chorthippus parallelus) , the hedgehog (Erinaceus europeus/concolor) and the brown bear (Ursus arctos) may serve as paradigms as Hewitt (2000) indicated. The refugia and recolonization routes of aquatic species, especially freshwater fishes are distinctly different from those of terrestrial creatures. The area of Danube middle and backward positions is usually thought of glacial refugia of freshwater fishes. When Pleistocene glaciations ended, the populations of the freshwater fishes in Danube recolonized to the north of Europe through Danube or other newly formed temporary rivers. During Pleistocene glaciations, China provided some key refugia for relict rare species because of its complex topography and many huge mountains of west\|east direction. However, few studies have been done to identify the refugia. Due to the influences of human activity, many potential glacial refugium areas, that had high biodiversity before, now are facing destructive threat. It is urgent to pay attention to the glacial refugia. We propose the following researches should be carried out in priority: (1) studies on glacial refugia and recolonization routes of typical relict species, and (2) roles of
出处
《生态学报》
CAS
CSCD
北大核心
2002年第11期1983-1990,共8页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 (3 0 0 70 1 43 )
上海市重点学科建设项目的部分内容
