摘要
现存两栖类 3个目的系统发生关系仍然没有统一意见 ,最广泛被接受的假说是单系起源 ,并且无尾类和有尾类为姐妹群关系而排斥蚓螈类 (蛙类假说 )。然而 ,这一假说一直存在争议。我们在测定了泽蛙线粒体基因组全序列的基础上 ,与已知其他的 6种两栖类进行详细的比较分析 ,同时选择了 11种高等脊椎动物的线粒体全基因序列 ,以硬骨鱼类作外群 ,用 2 2个tRNA基因合并数据进行系统发生重建分析 ,结果表明MP、ML树都强力地支持现生两栖类动物为单系群 ,并且有尾目和蚓螈目为姐妹群关系。这个结果与蛙类假说是相矛盾的 ,与Bolt (1991)在形态学基础上提出的有尾类和蚓螈类为姐妹群关系的假说相一致 ,并得到建立在线粒体和核rRNA基因数据基础上的许多分子研究的支持。另外还探讨了本结果与前人的研究不一致的原因 。
To date,there still is lack of a general consensus regarding the phylogenetic relationships of three living orders of amphibian among herpetologists.The most widely accepted hypothesis is the monophyletic origin in the class Amphibia,which proposed a sister-group relationship between Caudata and Anura (the Batrachia hypothesis) to the exclusion of the Gymnophiona.However,the phylogenetic relationship among living amphibians is still a controversial issue.The complete nucleotide sequence of the mitochondrial genome of Fejervarya limnocharis was detailedly compared with those of 6 other amphibians.The nucleotide sequences of 22 tRNA encoded by 7 amphibians mitochondrial genomes were combined and aligned to the homologous sequences of the 11 veterbrate taxa.Teleosts selected as outgroup,the phylogenetic analyses results show that MP and ML trees all strongly support the monophyly of living amphibians with respect to other living tetrapods and favor a sister group relationship for caecilians and urodeles.Robustness of our results was confirmed by high bootstrap support of all nodes in the trees.This result contradicts the Batrachia hypothesis,and is consistent with Bolt's hypothesis (1991) basing on the morphological data.The result was also supported by previous molecular studies based on the data from mitochondrial and nuclear rRNA genes.In addition,the reason for our result inconsistent with previous works and the shortcomings of phylogenetic analyses based on the complete mitochondrial genomes were also discussed.
基金
教育部骨干教师资助计划项目 (GG -180 -2 10 0 2 40 3 -1740 )
教育部留学回国人员启动基金资助~~
