海南和台湾蕨类植物多样性及其大陆性特征

Biodiversities and their continental features of the fern floras in Hainan and Taiwan island, China

海南和台湾是我国南部和东部两个最重要的大陆性岛屿 ,具有极为丰富的蕨类植物多样性 .特有现象揭示着植物区系和植物多样性的历史 ,间断分布揭示着与邻近或相关植物区系的联系 ;特别是在岛屿地区 ,这种现象和意义尤其明显 .海南有蕨类植物区系 5 5科、1 35属、4 6 6种 ,其中特有种有 32种 ,台湾蕨类植物区系 5 7科、1 4 2属、5 99种 ,其中特有种达 6 6种 .在海南与台湾两地 ,有共有属 1 0 4属 ,共有种仅有 1 76种 .台湾海峡出现始于晚白垩世 ,持续至第四纪 ;琼州海峡出现于早第四纪 ,因此 ,两地的特有现象远少于种子植物 台湾有 80 1种 ,海南有 5 0 1种 ,原因与蕨类植物具有更广的散布性相关 ,而且在被子植物中起重要作用的物种生物学障碍 机制 在蕨类是缺乏的 ;形态学的、生殖生物学特征导致蕨类植物具有较缓慢的物种演化历史和较低的灭绝率 Smith,1 972 .海南和台湾蕨类植物区系的比较还表明 。

Hainan and Taiwan are two most important continental islands of south China and east China, with the rather rich fern biodiversity. By research on endemism and disjunction, it could be imply the history of diversity of fern flora and could be reveal the relationship of the flora with its neighboring floras. In Hainan, there are 55 families, 135 genera and 466 species (32 endemic species), and in Taiwan, there are 57 families, 142 genera and 599 species (66 endemic species). Among those species, the shared genera has about 104, the shared species has only 176. Taiwan strait originated from Late Cretaceous, and had lasted to Quaternary; Qiongzhou strait occurred from early Quaternary, so the endemic species of ferns in Taiwan and Hainan island are more less that of seed plants (Taiwan has 801 endemic species of seed plants, Hainan has 501 endemic species of seed plants), the cause can be attributed to their greater dispersibility, because many of the speciation barriers which play a considerable role in angiosperms are absent in ferns; and some morphological and reproductive characters will results in that the ferns has the slower rate of speciation evolution and the lower extinction rate. Other an important cause is elevation, which it strongly affected on the species diversity and species diferentation of fern flora.