Study On Polymorphisms Of MtDNA D-loop Sequence Of Dazu Black Goat And Several Black Goat Species (Populations) Of Its Surrounding Areas

China is one of the countries that abound with livestock species. It is reported that there are 48 goat breeds in China. However, as new high-productive livestock species were imported constantly, the work including hybrid and improvement, artificial insemination (AIS), embryo transfer were proceeding profoundly. Our old native livestock species were facing a serial of competitions grimly and exclusively and accelerating the Number of livestock down, even were extinct.There are strong local characteristics of goat breeds (populations) in southwest region, especially in the Sichuan Basin. Dazu Black Goat population which has a high reproductive performance was found in recent years by Southwest University in Dazu County. The natural environment of its location was relatively closed and gene exchanges with the other goat species (populations) was fewer, so it can be saw as a separate population. In order to protect and make good use of the genetic resources, the studying team was performing basic research on the genetic diversity of Dazu black goat and several black goat species (populations) of its surrounding areas.To determine the gene diversity of the Black Goat, a complete fragment of mitochondrial DNA D-loop was sequenced for total number of 86 individuals from five Black Goat breeds. Based on goat's mtDNA whole sequnence from GENBANK, the genetic variety and divergence of these goats were analyzed by using DNAMAN, BioEdit, ClustalW, MEGA4.0, DNASP softwares. Unweighted Pair Group Method Using Arithmetic Average and neighbor-joining method were used to analyze the variation between populations through calculating genetic heterozygosis, polymorphic information content, Nei's genetic distance. The results showed that: 1. The fragment lengths of mtDNA and mtDNAD-loop in all goat breeds (populations) were about 16kb and 1210~1214bp, respectively, and no difference in nucleotide composition of mtDNA D-loop sequences between populations was found in my study. The largest number of site variants was in the sequence 400-850bp. The base composition of D-loop complete sequence in the tested breeds was about 60.0% of A+T, and about 40.0% of C+G.2. 50 haplotypes have been defined, and the polymorphic location is 311, including 229 parsimony informative polymorphic sites, and 82 singleton polymorphic sites. Haplotype diversity are 0.91912-1.00000, Nucleotide diversity are 0.01455-0.02171.A11 goat breeds (populations) have abundant polymorphism in mtDNA D-loop sequence.3. The genetic distance of Lezhi Black Goat population is highest than the other four Black Goat populations and that of Yingshan Black Goat population is lowest.4. Clustering analysis that based on matrix D_a, Dxy shows that the all goat breeds (populations) form 4 parts. First, Yingshan Black Goat and Chuandong Black Goat were clustered together, and then was Dazu Black Goat, Lezhi Black Goat and Guishan Black Goat.