四种绒螯蟹分子分类与系统发育

利用PCR技术，扩增了中华绒螯解、狭额绒螯蟹线粒体16SrDNA片段，经测序，与GenBank数据库中的日本绒螯解16SrDNA同源序列进行比较。结果显示，在长为376bp的16SrDNA同源序列中有33个多态性核革酸位点（8．78％），其中种间多态性核苷酸位点28个（7．45％），种间差异远大于种内差异。引入方蟹科其它近缘种类厚纹蟹、相手蟹和张口蟹的16SrDNA同源序列与上述4种绒螯蟹比较分析，MP法和NJ法构建的分子系统树表明：中华绒螯蟹与日本绒螯蟹亲缘关系最近，首先聚在一起，然后与台湾绒螯蟹聚为一支，狭额绒螯蟹则为相对独立的一支，且进化速度大于前3种绒螯蟹，但最后与前者仍聚在同一组，狭额绒螯蟹只是绒螯蟹属系统进化中的一个侧支，故本研究结果不支持Sakai（1983）和Guo等（1997）把狭额绒螯蟹和台湾绒螯蟹各自立为新属的观点。

MOLECULAR TAXONOMY AND PHYLOGENY OF FOUR SPECIES OFERIOCHEIR (DECAPODA: BRACHYURA: GRAPSIDAE)

The taxonomy and phylogenic relationships of four species of Eriocheir were investigated by mitochondrial DNA sequencing analysis. Parts of 16S ribosomal DNA (16S rDNA) were amplified with the polymerase chain reaction (PCR). A total of 537 bp nucleotide site was sequenced for 6 individuals from Eriocheir sinensis and E. leptognathus ,which were collected from Chong ming island and San jia Port in Shanghai, respectively. 33 (8 78%) polymorphic nucleotide sites were detected. 28 (7 45%) sites were interspecific sequence variation and the intraspecific genetic difference was small. Four haplotypes were found in both E. sinensis and E.leptognathus . Combined with the previously reported sequences (376 bp) from Pachygrapsus transversus (Sturmbauer et al .,1996), Sesarma ayatum, Chasmagnathus granulat (Schubart et al ., 1998), E. japmmonicus and E. formosa (Cheng et al .,1998), phylogenetic trees were constructed with Maximum Parsimony and Neighbor Joining method. The results indicated that E. sinensis to be more closely related to E. japonicus than to any other Eriocheir species. E. formosa formed a clade with E. sinensis and E. japonicus that was separated from the relatively independent clade formed by E. leptognathus . However, The two clades were clustered into the same group, although the evolutionary speed of E. leptognathus was faster than those of other Eriocheir species. This result was not consistent with Sakai's and Guo's views (Sakai, 1983; Guo et al .,1997) that E. leptognathus and E. formosa were refered to a new genus, respectively. This research also indicated that the genetic variation was very low in the commercially important species E. sinensis because of the fast flow of gene caused by artificial transplant in aquaculture.