Study On Molecular Phylogeography Of Several Economical Marine Fish Base On AFLP Markers

In the present study, AFLP molecular marker was used to estimate thepopulation genetic diversity and genetic structure of Lateolabrax maculates, Coilianasus, Liza haematocheilus, Collichthys lucidus, Hexagrammos otakii, Clupeapallasii and H. agrammus. Phylogenetic relationships between L. maculates and L.japonicus, C. lucidus and C. niveatus were also discussed. The results of the presentstudy were as follow:（1） To examine population genetic structure and phylogenetic relationship of L.maculates and L. japonicus, samples of L. maculates from Chinese Coast andsamples of L. japonicus from Japanese Coast were collected and analyzed by AFLP.The results showed that Nei gene diversity and Shannon’s information index ofAriake Sea were higher than the other6populations. Two clades were detected byUPGMA tree were, which were Chinese clade and Japanese clade, respectively.Pairwise F_stbetween L. maculates and L. japonicus was significantly higher thanthat between populations of L. maculates and between populations of L. japonicus.Gene flow values between populations of L. maculates and between populations of L.maculates were higher than1, while gene flow between these two species was lowerthan1. The results of present study supported that the L. maculates and L. japonicuswere different speices.（2） AFLP marker was used to examine the genetic diversity and geneticstructure of Coilia nasus and to analyze the genetic differentiation between Chineseand Japanese populations. The results showed that all individuals from Japanesecoast were clustered into one clade, but this clade was still surrounded by Chineseindividuals on the whole and no obvious differentiation was detected by UPGMA.Pairwise F_stvalues between Chinese populations and Japanese populations were higher than those between Chinese populations and between Japanese populations,but significantly lower than that between C. nasus and C. mystus. The results ofpresent study indicated limited gene flow between Chinese populations and Japanesepopulations, but did not supported they were different species.（3） Eight populations from Chinese and Japanese coast were analyzed by AFLP.The results showed that proportion of polymorphic loci were very low, only22.73%-38.46%. These8populations were clustered into two clades, namely,southern group including populations from Zhujiang and Yunlin and northern groupincluding the other6populations. AMOVA and pairwise F_stalso supported theseparation of north and south populations of L. haematocheilus. The present studydemonstrated that L. haematocheilus was indeed composed of at least twogenetically divergent species, but not three cryptic species in the NorthwesternPacific.（4） In the present study, the genetic diversity and population genetic structure ofC. lucidus were examined by AFLP marker. C. niveatus was collected as theoutgroup to discuss the differentiation between these two species. A total of458bands were identified from60individuals and the percentage of polymorphic bandswas95.85%. These two species clustered into two clades. Among the5populationsfor C. lucidus, populations from Zhoushan and Shanghai clustered into one clade,populations from Wenzhou and Xiamen clustered into another clade, and these twoclades subsequently clustered with Shenzhen population. The pairwise F_strangedfrom0.1648（between populations from Zhoushan and Shanghai） to0.3074（betweenpopulations from Shenzhen and Shanghai）. Gene flow values among differentpopulations were lower than1. The results of present study indicated the limitedgene flow among different geographic populations, in conformity with the point thatC. lucidus and C. niveatus were different species.（5） Six geographic populations of H. otakii from Chinese and Japanese coastawere further analyzed to estimate the population genetic structure, due to thedifference of results between morphological and microsatellite DNA analysis. Theresults showed that the genetic diversity of Hachinohe population was the highest and the lowest occurred in Dandong population. Two clades were detected byUPGMA tree, but no significant genealogical branches or clusters corresponding tosampling localities were detected. Pairwise F_stvalues （0.016-0.122） showed nogenetic divergence among different geographic populations and gene flow valueswere high among5populations. The results of the present study supposed that H.otakii was a random mating population.（6） AFLP marker was used to estimate the population structure andphylogeographic pattern of Clupea pallasii in North Pacific. The genetic diversityindices of8populations were similar to each other. Two branches were detected, oneof which consisted of all individuals from Sitka Island and another consisted of theother7populations. All individuals of Okhotsk Sea formed into one small clade andno significant genealogical branches or clusters corresponding to sampling localitieswere detected. The pairwise F_stvalues between Sitka Island and other populationswere higher and the lowest differentiation was observed between populations ofWest Kamchatka and Ishikari Bay. Gene flow values between Sitka Island and otherpopulations were less than1, contrary to the other combinations. The results ofpresent study supported the opinion that clade A should originate from some refugeof the Northwestern Pacific and clade B should originate from some refuge of theEast Pacific.（7） Two populations of H. agrammus from Qingdao and Lidao of Weihai coastwere analyzed by AFLP marker. The results showed that genetic diversity of the twopopulations was similar to each other. Two branches were detected by UPGMA treewith no significant genealogical branches or clusters corresponded to samplinglocalities. The pairwise F_stvalue between the two populations was0.056and geneflow was more than4. The results of the present study indicated that H. agrammuswas a random mating population and showed the similar genetic diversity with H.otakii.