Studies On Collichthys Lucidus And C. Niveatus Based On Morphological And Genetic Markers

C. lucidus and C. niveatus, which belong to Perciformes, Sciaenidae, Collichthys, both are important economical species in China.Our study based on traditional morphology, otolith's morphology and completely mitochondrial DNA sequence to analysis the relationship between C. lucidus and C. niveatus. Intensive studied the classification status and genetic relationship between C. lucidus and C. niveatus. And through the method of traditional morphology, otolith's morphology and D-loop sequence, Cyt b gene in mtDNA, we also studied the morphological and genetics'difference among 5 populations for C. lucidus in China's coasts.1. Use traditional morphology and otolith's morphology to distinguish the morphological differences between C. lucida and C. niveatus. Take photographs at the head apophysis, anal-fin's first fin spine, the branch of the air bladder, the color of oral cavity and the shap of the otolith. Analysis fourteen traditional morphological characters and seventeen otolith's morphological characters between C. lucida and C. niveatus by PCA (principal component analysis), one-way ANOVA and discriminant methods. In this study, we found otolith's morphological method have excellent feature in fish morphology analysis.2. The entire mitochondrial DNA sequence (mitogenome) of Collichtys lucida and C. niveatus were determined using long PCR and traditional PCR technologys. The complete sequence of the C. lucida mitochondrial genomes is 16451bp and C. niveatus is 16450bp in length. It is showed a genome organization similar to other reported fish mitochondrial genomes. Both them contained 37 genes (2 rRNAs,22 tRNAs and 13 protein coding genes) and 2 non-coding region (D-loop control region and WANCY region). The tRNAGln, tRNAAla, tRNAAsn, tRNACys, tRNATyr, tRNASer(the second one), tRNAGlu, tRNAPro genes were encode on the light strand (L strand), and the remainders are on the heavy strand (H strand). All protein-coding genes begain with ATG as initiation codon. Most of the protein-coding genes, including ND1, COI, ATPase8, ATPase6, ND4L, ND5, ND6 and Cyt b had integral termination codon, while the others had incomplete termination codon. Among the 13 protein-coding genes, only ND6 was located on the L strand; the others were on the H strand. The conservative sequence blocks (CSB-D,-E, and-F) and TAS in the D-loop control region were characterized and analyzed anong the L. polyactis, L. crocea, C. lucidus and C. niveatus. Phylogenetic tree and molecular evolutionary analysis of 13 protein-coding genes, COI, Cyt b and 16S genes conducted using MEGA version 3.0 showed the result is the same like the morphology research.3. Fourteen traditional morphological characters and seventeen otolith's morphological characters of populations of Collichtys lucida from Lianyungang, Shanghai, Zhoushan, Wenzhou and Shenzhen were analysed by PCA (principal component analysis), one-way ANOVA, clustering and discriminant methods. The result realized that there were significant between north group and south group, and a certain extent of geographical variances in distribution exised.4. To assess the roles that Pleistocene ice ages have played in the evolutionary history of the marine organisms and ecological connectivity among marine populations in the Northwestern Pacific, we explored the intraspecific phylogeographic pattern and dispersal patterns in redlip mullet, Collichtys lucida. Three distinct lineages were found, which might be isolated and diverged in different marginal seas of the Northwestern Pacific during Pleistocene low sea level stands. There were strong geographical differences in haplotype frequencies of the 3 lineages. Molecular variation analyses and the conventional population statistic FST revealed significant genetic structure. These results indicated that gene flow in C. lucida is far more restricted spatially than predicted by the potential dispersal of this species. The lack of phylogeographic structure in East China Sea may reflect the recency range expansion after the Last Glacial Maximum and insufficient time to attain migration-drift equilibrium.