| Objective to provide the evidence of theory in well-bred loach selection, themorphological characters of loaches (Misgurnus anguillicaudatus) which distribute inPoyang lake were studied and compared, and the molecular biological characters atDNA level were also further researched with the methods of SSR marker from thenuclear DNA and sequences analysis of mitochondrial cytochrome b gene (cyt b).First, the biological characters were investigated. According to the spot of theirbodies, the loaches of Poyang lake can be divided into three groups: the big-spotloach, small-spot loach and non-spot loach, and the color change of the big-spot loachwere also observed. The countable and measurable properties data indicated that thereare no distinctly morphologic differences among the three kinds. The colors were notdistinctly changed for fourteen days' temporarily manual cultured; the size and thenumber of the spots were not changed either.Second, SSR technique was applied to analysis the genetic variation among thethree kind loaches. A total of 67 loci were detected from the three kind loaches byusing six primers. The polymorphic loci of big-spot loach is 45, the percentage ofpolymorphic loci is 67.16%, the polymorphic loci of big-spot loach is 39, thepercentage of polymorphic loci is 58.6%, the polymorphic loci of big-spot loach is 15,the percentage of polymorphic loci is 22.39%. The excepted heterozygosity of thebig-spot, small-spot and non-spot loach are 0.1554,0.1799,0.0857 and the PIC are0.2737,0.3626,0.1989. The results showed that the genetic polymorphic among thethree are very low, especially in the non-spot loach. The genetic similarity index andgenetic distance between the big-spot and the small-spot loach were 0.9676 and0.0329, big-spot and none- spot loach were 0.9449 and 0.1552, small-spot andnone-spot loach were0.9706 and 0.0299. The phylogenetic tree was constructed andanalyzed by distance method. Result show that the non-spot is more closely related tosmall-spot than to big -spot loach.Third, phylogeographic structures of the three kind loaches were studied basedon mitochondrial cytochrome b gene sequences. The 1140bp sequences were obtained by PCR amplification in the three kind loaches. Thirteen haplotypes were identifiedfrom 28 samples with 130 variation site. Six peculiarly haplotypes were present onlyin big-spot loach, the small-spot and non-spot loach only have one and two peculiarlyhaplotypes. Phylogenetic trees produced by the methods of maximum parsimony (MP)and neighbor-joining (NJ) indicated that four haplotypes of the big-spot loach wereclustered into two groups with high confidence level. The genetic distance betweenthe small-spot loach and the non one is 0.0145, the distance between the big-spotloach and small spot loach and distance between big-spot and non one are farther. TheDs matrix tree show the non-spot is more closely related to small-spot than to big-spot as the same result as the SSR marker.The results indicated that there may have many kind different body pigmentloathes in Poyang lake. The preliminary research of selection indicates the geneticcharacter was stable, which belongs to quantitative traits loci (QTL). Results alsoindicated that the loach in Poyang lake may be have population heterozygosis.
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