Abstract: [Objective] To assess the genetic and evolutionary relationships between locally bred dairy goat varieties in China and those introduced abroad. [Method] Four domestic dairy goat breeds （Wendeng dairy goat, Guanzhong dairy goat, Laoshan dairy goat, and Ya′an dairy goat） in China and three introduced breeds （Alpine dairy goat, Toggenburg dairy goat, and Saanen dairy goat） from New Zealand were used as research subjects. Peripheral blood samples were collected from 33 individuals and the genomic DNA was extracted. The full-length of D-loop region of mitochondrial DNA （mtDNA） were amplified by PCR assay and then sequenced. The obtained sequences were subjected to bioinformatic analysis to uncover the genetic diversity and evolutionary relationship of various dairy goat breeds.[Result] The contents of A/T in the mtDNA D-loop region of 7 dairy goat breeds were higher than those of G/C. A total of 82 variable sites, 25 singleton variable sites, and 55 parsimony informative sites were found. The haplotype diversity （Hd） of the studied dairy goat breeds ranged from 0.905 to 1.000, and the nucleotide diversity （Pi） ranged from 0.001 51 to 0.013 32. There were 26 haplotypes in total, including 5 haplotypes each in Wendeng dairy goat and Saanen dairy goat, 4 haplotypes in Alpine dairy goat, 3 haplotypes each in Laoshan dairy goat, Toggenburg dairy goat, Guanzhong dairy goat, and Ya′an dairy goat. The ranges of average nucleotide diversity （K_XY）, nucleotide variation （D_XY）, genetic differentiation index （G_ST）, and genetic differentiation index （F_ST） were 6.400 00-38.450 00, 0.005 79-0.034 76, 0.000 00-0.186 05, and 0.231 56-0.971 52, respectively. According to the phylogenetic tree among different breeds, Wendeng dairy goat and Laoshan dairy goat were genetically clustered together into one branch. The genetic relation between Guanzhong dairy goat and three New Zealand dairy goat breeds was closer, proving that Guanzhong dairy goat was bred by hybridization of local breeds with foreign dairy goats. Ya′an dairy goat had the greatest genetic distance from the other breeds. [Conclusion] In Chinese dairy goats, there are two lineage origins with no evidence of population expansion. The locally bred dairy goats in China are highly genetically linked with foreign dairy goats. Wendeng dairy goat has closely genetic relationship with Laoshan dairy goat, and Ya′an dairy goat may have experienced regional isolation during the genetic evolution.

Key words: dairy goat, mitochondrial DNA, D-loop region, heredity and evolution