| Common hair-fin anchovy, Setipinna tenuifilis, which belongs to familyEngraulidae, order Clupeiformes, is an economically important small species. S.tenuifilis is widely distributed from westen Indian Ocean to northwestern PacificOcean, especially in Bohai Sea, Yellow Sea, East China Sea and South China Sea.The fishing pressure of small economic marine fish such as S. tenuifilis is gettingbigger with the resources of traditional economic marine fish decreased and thenatural resource of S. tenuifilis is decreasing. In this study, we systemataciallyanalyzed S. tenuifilis population genetic diversity and genetic structure by usingmorphological analysis, otolith morphological analysis and mtDNA meloculargenetic analysis, discussed and revealed the formation mechanism of itsgeographical pattern. This study provides theoretical basis for rational utilization andscientific management of S. tenuifilis resources.(A) Morphological analysis of S. tenuifilis population(1) Thirty morphological indices including7meristic characteristics and23measurement characteristics of129individuals from5populations (Dongying,Qingdao, Wenzhou, Xiamen and Beibu Bay) were measured by conventionalmorphological and landmark morphological methods and the data was analyzed byusing oneway-ANOVA analysis, discriminant analysis, principal componnet analysisand cluster analysis. The results of meristic characteristics showed that there was nosignificant difference between populations; one way-ANOVA analysis showed that16indices were insignificantly different between Xiamen population and Beibu Baypopulation,while14indices were significantly different between Wenzhoupopulation and Beibu Bay populaiton; the results of discriminant analysis showedthat the correct classification ratio distributed from90.9%to100%, and the averageclassification ratio was94.5%, scatter diagram of discriminant analysis showed thatsamples of population Xiamen and Beibu Bay gathered for one group and other populations gathered for another group; the results of principal component analysisshowed that the first8principal components explained82.5%of morphologicaldifference; the result of cluster analysis showed that population Beibu Bay andXiamen were pooled in one group, then pooled with other populations. The results ofmultivariate statistical analysis methods showed that individuals from Wenzhoupopulation had a great diffenece with other populations, the reason might be freshwater from Yangtze Rvier changed the physical and chemical environment of thisregion.(2) Otolith morphological characteristics of129individuals from5populationsof Chinese coastal water were analyzed by shape index method and elliptic Fouriermethod. The results of otolith morphological analysis is the same as morphologicalanalysis. The results of multivariate statistical analysis methods showed that otolithmorphology of individuals from Wenzhou population got a great difference withother populations, the reason might be fresh water from Yangtze Rvier changed thephysical and chemical environment of this region and the environment had an effecton S. tenuifilis s otolith.(B) Genetic analysis of S. tenuifilis population(1) In order to detect the genetic structure and genetic difference of S. tenuifilispopulations in Chinese coastal waters, genetic analyses were taken place to detecttheir population genetic variation. A total of153individuals from7locations(Dongying, Yantai, Qingdao, Nantong, Wenzhou, Xiamen and Beibu Bay) weresequenced at the5’ end of mtDNA control region. A39-bp tandem repeatedsequence was found at the5’ end of the segment and a polymorphism of tandemrepeated sequence was detected among7populations. The topology ofneighbor-joining tree and Bayesian evolutionary tree showed no significantgenealogical branches or clusters of samples corresponding to sampling locality.Hierarchical AMOVA analysis and conventional pairwise population Fstvalue atgroup hierarchical level implied that there might have genetic divergence betweensouthern group (population WZ, XM and BB) and northern group (population DY,YT, QD and NT). Both mismatch distribution analysis and neutrality tests showed S. tenuifilis had experienced a recent population expansion. According to divergencerate of control region sequence (5%-10%/MY), the expanding time of group BohaiSea and Yellow Sea might be about97400-194800years before, the time of groupEast China Sea and group South China Sea might be about45700-91500and17300-34500years before, separately. We concluded that there might have threedifferent fishery management groups of S. tenuifilis and the late Pleistocene glacialevent might have a crucial effect on present-day demography of S.tenuifilis in thisregion.(2) Genetic study was carried out to analyze202individuals of S. tenuifilis from7populations of Chinese coastal water. We determined35control region sequence toanalyze their sequence structure. length of control region was ranged from1193bpto1271bp. Termination associated sequence, central conserved domain andconserved sequence block were identified. Tandem repeat sequence was found in5side of control region and it contained an extended termination associated sequence(ETAS), six conserved sequence block (CSB-D, E, F,1,2,3) were identified andcharacteristic sequences were given. We analyzed length polymorphism of controlregion hypervariable region I of202individuals, which was found betweenindividuals and no length heterogeneous phenomenon was detected intraindividually.Frequency of repeat sequence of202individuals was statistically analyzed. Wefound that the frequency of7repeats is the highest in population Beibu Bay whilethe frequency of6repeats is the highest in other six populations. The results ofChi-square test showed that extremely significant difference was detected betweenpopulation Beibu Bay and other six populations. Analysis of repeat sequence couldbe used in S. tenuifilis genetic study as an accessory method. |
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