Study On Genetic Diversity And Breeds Differentiation Of Tibet Sheep

The molecular techniques of random amplified polymorphic DNA (RAPD) were used to investigate the genetic diversity of eight breeds of Tibet sheep from Gansu and Qinghai province of northwest China. The genetic diversity and relationships and differentiation of these breeds were evaluated and discussed with several analysis methods of modern population genetics. In 25iiL reaction systems, 60?--l2Ong DNA templates, 4～ 8pmol primers, 2. 0mM Mg2+ ,1～2. 5U Ta DNA polymerase and 150～ 200 M dNTPs were the optimization conditions of RAPD reaction of Tibet sheep in GeneAmp PCR System 2400. The parameter of 40 cycles after 3mm pre-denaturalization were that:940C 1mm, 36 0C 1mm, 72CC 2. 5mm, 720C 10mm. As above, the results of RAPD reaction could be repeated and the reliability of one would be lifted increasingly. 4447 fragments of RAPD were detected within 48 animals with 18 arbitrary oligonucleotide primers, and the percentage of polymorphic fragments was 88. 17%. The average genetic diversity index (Ho) within breeds was 0.37. The average diversity over all populations (Hsp) was 1. 51. Portioning of genetic variability on average showed that, 24. 5% distributed within and 75. 5% between breeds. The average genetic distance index (D) was 0. 177(0. 152?. 197) within and 0.492(0.419 0.569) between breeds of Tibet sheep. The genetic variation between breeds was bigger than within one. The results showed that the genetic diversity between breeds was remarkably abundance in nuclear DNA, and relatively scarce within breeds of Tibet sheep. The differentiation of breeds had exited in Tibet sheep. The breeds of Tibet sheep could be divided into Altiplano Meadow Type (AMT) and Valley Grassplot Type (VGT). Tangehang black Tibet sheep is a new breed. At last, RAPD analysis was effective method of the studies on genetic diversity, genetic construction, origin and genetic ? differentiation of domestic animals.