| The genus Brachymystax Günther,1866,belonging to Salmonidae,Salmoniformes,is a coldwater fish,and there are three lenoks of genus Brachymystax(B.lenok(Pallas,1773),B.tumensis Mori,1930 and B.lenok tsinlingensis Li,1966)in China which mainly distribute in the rivers of northern China and Qinling Mountains.Some ichthyologists have reported the lenoks distributing in Amur River as two separate species,B.lenok and B.tumensis,respectively.While the taxonomic status of B.lenok tsinlingensis,distributing in Qinling area,is controversial since it was found.On the one hand,B.lenok tsinlingensis was considered as a subspecies of B.lenok,on the other hand,it was believed as an independent species.Therefore,“group” was used in the present study.Due to environmental pollution and overfishing,B.lenok tsinlingensis has been listed as a class II state protected wild animal in China Red Data Book of Endangered Animals since 1998.Thus,the research refer to taxonomic relationship among three groups(B.lenok tsinlingensis,B.lenok and B.tumensis)is very essential and necessary for the rational protection of the germplasm resources of B.lenok tsinlingensis.In the present study,three morphotypes of lenoks from Amur River and the Qinling area were collected to explore the genetic diversity among three groups and to clarify the taxonomic status of B.lenok tsinlingensis,based on morphological variation,the differences of mtDNA D-loop sequences and polymorphic microsatellite loci.The main results of this study are displayed as follows:1.Multivariate morphometrics(sample size = 178)and geometric morphometrics(sample size = 169)methods were used to analyze the morphological variation of three Brachymystax groups.Based on multivariate morphometric analysis,results of the one-way ANOVA showed that 5 meristic characters and 32 standardized morphometric characters were significantly different(P<0.01)between any two of the three groups.Principal component analysis indicated the cumulative contribution of the top two principal components was 90.279%.Effective linear discriminant formulas were obtained from fourteen standardized morphometric characters,with the discriminating accuracy of 99.4% in three groups.Results of geometric morphometric analysis also indicated signifcant morphological variation in body shape among three groups.CV1(65.77%)and CV2(34.23%)were well explained 100% of the observed variation among three groups by canonical variate analyses.Discriminant function analysis showed all samples with six exception were correctly reclassified,and the discriminanting accurate were above 90%.These two morphological results indicated significant difference of morphological structure between any two of three groups.2.45 haplotypes from 217 samples of Brachymystax spp.were obtained according to the sequence of mtDNA D-loop region.No shared haplotypes were found between any two groups of Brachymystax,which indicated high differention among three lenoks.The phylogenetic trees and network based on 45 haplotypes indicated that three groups were monophyletic,and every group looks as an independent lineage.3.14 polymorphic microsatellite loci were obtained from 86 microsatellite loci,and the results of genetic diversity were similar to those of mtDNA D-loop region.Among these groups,the genetic distance and degree of differentiation between B.lenok tsinlingensis and any one of B.lenok and B.tumensis were all bigger than the distances of B.lenok and B.tumensis.In addition,three polymorphic microsatellite loci of Ble Tet6,Ble Di58 and Ble Tri08 could be used as molecular markers to identify the samples of B.lenok tsinlingensis.On the basis of the results of morphological and molecular analysis,B.lenok(Pallas,1773)and B.tumensis Mori,1930 could be considered as two species,it is also suggested that the B.lenok tsinlingensis Li,1966 could be regarded as an independent species,and could be renamed as B.tsinlingensis Li,1966 in the future. |
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