The Taxonomic Status Of Amphioxus In China Based On Morphology And Molecular Phologeny

Amphioxus is one of the oldest, the most precious marine animals. It is called the living fossil in the process of evolution from invertebrate to vertebrate, and so it has high academic research value and econmic value.1. We analysed nineteen morphological characters of amphioxus by One-way ANOVA principal component analysis, cluster analysis, and discriminant methods. The results of One-way ANOVA showed that significant difference in means of 19 morphological characters existed among three different amphioxus populations, and there were great variance among populations than within population. The results of principal component analysis showed that four principal components were constructed by factor loading, and the contributory ratios of the first four principal components were 60.42%, 9.18%, 7.2% and 7.07%, respectively. The first principal component was affected by total body length, length of metapleural fold, anus to tip of snout and tip of snout to atriopore. In the result of cluster analysis, amphioxus were mostly divided two groups. The first group was composed by Qingdao and Rizhao, and the other group was composed by Xiamen. The total accuracy of discrimination on amphioxus was 98.8%, and only one sample from Rizhao population was appearing in Qingdao population. The discriminant functions of three populations were established, however all of accuracy by the functions were not changed.2. Cyt b, COI and 16S rRNA gene fragments of amphioxus from Xiamen, Qingdao and Rizhao were amplified by PCR, then the PCR products were purified and sequenced. We also got sequences of Japenese amphioxus from GENEBANK. The Cyt b gene fragment was 472bp, and the AT content was higher than GC content, 62.8%. The COI and 16S rRNA gene fregments were 403bp and 574bp, respectively, and the AT content were also higher than GC content, 60.9% and 63.2%. The genetic distance based on Cyt b gene between Xiamen and the other three populations is 0.21. However the genetic distance among the other three populations is 0.01. And the genetic distance based on COI and 16S rRNA between Xiamen and the other three populations were 0.18 and 0.17, respectively. All of the phylogenetic trees revealed that Qingdao, Rizhao and Japenese populations were pooled into one group, and Xiamen population was pooled into the other group. Above all, our results supported the viewpoint that Qingdao amphioxus and Xiamen amphioxus might belong to different species.