粉条儿菜属(肺筋草科)的地理分布及其物种多样性和分化中心

粉条儿菜属(AletrisL.)隶属于肺筋草科,全世界有23种1变种,东亚有18种1变种,北美东南部有5种,为典型的东亚-北美间断分布的属.本文在种(变种)的水平上,研究了粉条儿菜属的地理分布及其分布中心和多样化中心,并对其起源和分化以及现代洲际间断分布格局的成因进行了分析.结果表明,(1)中国共分布有粉条儿菜属植物15种1变种,而广义的横断山地区集中分布有13种1变种,是东亚粉条儿菜属植物分布最为集中的地区,而且包含该属植物各个进化阶段的代表.因此,广义的横断山地区是粉条儿菜属在东亚的分布中心和多样化中心.(2)根据粉条儿菜属及其近缘属的分布格局推测,该属可能在不晚于第三纪早期,起源于古北大陆.东亚和北美的粉条儿菜属植物形态区别明显,应该是隔离分化的结果.(3)该属植物可能曾经广布于北半球,后来地质、气候以及冰川等因素的变化,导致该属在一些地区灭绝,而仅存于东亚和北美东南部.(4)尽管横断山及其周边地区是东亚粉条儿菜属的多样化中心,但该地区很可能并不是粉条儿菜属最早的分化中心,因横断山地区周边的一些特有种可能是在晚近的时期形成的新特有种;另外,东亚粉条儿菜属一些原始的种类主要分布于我国中东部到日本一带.所以,中国中东部到日本一带可能是粉条儿菜属早期的分化中心.

Geographical Distribution, Species Diversity and Speciation Centers of Aletris (Nartheciaceae)

Belonging to Nartheciaceae,Aletris L.has twenty three species and one variety of which there are 18 species and one varieties in east Asia and five species in the southern part of North America,so that it is a genus with a typical East Asia-North America discontinuous distribution.On species(variety) level,the geographical distribution,and distribution and diversity centers of Aletris L.were studied and the causes for its origin and speciation as well as its modern inter-continent discontinuous distribution were explored.The results showed that(1) There are 15 species and one variety distributing in China and 13 species and one variety distributing in Generalized Hengduan Mountains Region,so that the region is the area where Aletris L.plants most densely distribute in East Asia and representative Aletris L.plants at all the evolution stages can be found.Therefore,generalized Hengduan Mountains Region is the distribution and diversity centers in East Asia.(2) It is presumed according to the distribution patterns of Aletris L.and its genetically close genera that Aletris L.probably originated in Laurasia not later than the early tertiary.There are clear-cut morphological differences between Aletris L.plants in East Asia and North America,which should be the result of isolated speciation.(3) The genus may have probably widely distributed in Northern hemisphere and become extinct in this region late on because of geological,climatic and glacier changes,so that it only remain in East Asia and the southern part of North America.(4) Although Hengduan Mountains Region and its surrounding regions are the diversity center of Aletris L.in East Asia,these regions are not the speciation center.(5) Some endemic species in the regions surrounding Hengduan Mountain Region are probably the new endemic ones that had formed in the neoid period.In addition,some primitive Aletris L.species in East Asia mainly distribute in East China and Central China and Japan and thus East China and Central China and Japan are probably the early speciation center.