The aim of the study was to investigate polymorphism and evolution in South China chickens by the tandem repeat LEI0258 located within the B region of the chicken major histocompatibility complex(MHC-B region).Genotypes and sequences of LEI0258 were obtained from 12 Southern China chicken breeds and 2commercial chicken breeds,and then these data were used to analyze genetic diversity and construct median-joining network.A total of 62 alleles were defined by DNA sequencing ranged from 182 to 501bp in 580 sam...