| Chinese was famous for the abundance of the indigenous pig breeds. There were 128 indigenous pig breeds recorded in the Domestic Animal Diversity Information System of FAO. However, lots of commercial pig breeds with high performance of growth and meat factor were introduced into China in the last decades for the market demand. The farmer would like to feed the crossbred between these breeds and indigenous pig breed or just the commercial breeds, rather than the indigenous pig breed, which leaded to the size of each indigenous pig breed decreased dramatically and many of them were endangered. Studying on the genetic diversity of Chinese indigenous pig breeds have been carried out in nowadays. The study result of genetic diversity of Chinese indigenous pig breeds with the microsatellite markers recommended by the FAO-ISAG would present the gist for conservation of these breeds. This study is one of the important parts of the project "Measurement of the genetic distance between Chinese indigenous pig breeds" launched in the autumn of 1999. The conclusion was followed as:(1) In this study, all of these markers were polymorphic in the 18 Chinese indigenous pig breed, the smallest number of alleles was 8 (SW951), the largest one was 31 (CGA and S0005), the average was 19.34; the lowest polymorphic information content was 0.584 (S0218), the highest one was 0.896 (CGA), the average was 0.773; all of these breeds shared 57 alleles in 22 loci, but there was no specific allele for a breed.(2) The Neighbor-Joining trees constructed from the Cavalli-Sforza and Edwards' chord distance Dc and Nei's genetic distance Da were consistent with each other; but the NJ and UPGMA trees produced from the Da genetic distance had some difference between them; the cluster tree of these breeds with the UPGMA was closer to the distribution of these breeds in geography, and it also had some difference from the classification of them in the book of Pig Breed in China.(3) The UPGMA tree was consisted of one small peripheral breeds and two steady inner branches, the peripheral breeds included the Min pig and Mashen pig of the North China Type and the Xiang pig and Diannan Small-ear pig of the South China Type; the two inner branches were mainly consisted of the Central China Type and Southwest Type respectively, the former branch included the breeds of the Shazhi Ling pig, Daweizhi pig, Ningxiang pig and Taoyuan pig from the Central China Type, the Pengzhou Mountanious pig from the Southwest Type and the Hetao Large-ear from the North China Type; in the later branch, the breeds of the Kele pig, Fuyuan pig, Rongchang pig, Chenghua pig and Neijiang pig and the Tibeta pig from the PlateauType clustered together firstly, then met the Guanling pig from the Southwest Type and the Hanjiang Black pig from the North China Type.(4) When the 18 indigenous pig breeds analyzed with other breeds in the project "Measurement of the genetic distance between Chinese indigenous pig breeds", the Min pig clustered with other breeds from the North China Type, the Xiang pig and Diannan Small-ear pig clustered with other breeds from the South China Type. But the Hanjiang Black pig clustered with the breeds from the Southwest China Type and the Hetao Large-ear pig clustered with the breeds from the Central China Type, which was not consistent with the classification in the book of Pig Breed in China.(5) Supposed the mutation rate of the microsatellite was 4.5 x 10-4 and 8.0 x 10-5 per year, the estimated differentiation time among the Chinese indigenous pig breeds were ranged from 413.8 to 2036.8 and 2327.8-11457.2 year from the Nei's standard genetic distance, respectively. The average differentiation time between the indigenous pig breeds and the commercial breeds were 2400.4 and 13803.95 with different mutation rate of the microsatellite.(6) More attention on breed conservation should be given to the Mashen pig in the 18 Chinese indigenous pig breeds. There was great genetic variation stored in other breeds who had large population. The utlization...
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