Genetic diversity and population structure of Chinese pony breeds using microsatellite markers.

China is one of the principal origins of ponies in the world. We made a comprehensive analysis of genetic diversity and population structure of Chinese ponies based on 174 animals of five indigenous Chinese pony breeds from five provinces using 13 microsatellite markers. One hundred and forty-four alleles were detected; the mean number of effective alleles among the pony breeds ranged from 5.38 (Guizhou) to 6.78 (Sichuan); the expected heterozygosity ranged from 0.82 (Guizhou) to 0.85 (Debao, Sichuan). Although abundant genetic variation was found, the genetic differentiation was low between the ponies, with 6% total genetic variance among the different breeds. All the pairwise F(ST) values were significant; they varied from 0.0424 for the Sichuan-Yunnan pair to 0.0833 for the Guizhou-Sichuan pair. All five pony breeds deviated from Hardy-Weinberg equilibrium, except the Yunnan pony. Phylogenetic trees of the five pony breeds based on genetic distances were constructed using a neighbor-joining method. The Sichuan and Yunnan ponies were grouped into the same branch, with a high bootstrap support value (97%). Guizhou and Ningqiang ponies were clustered into the same branch with a bootstrap value of 56%, whereas the Debao pony was placed in a separate group, with a bootstrap value of 56%. This grouping pattern was supported by genetic structure analysis.