Investigation of the diversity and origins of Chinese dairy goats via the mitochondrial DNA D-loop1,2

To determine the genetic diversity, origins, and the phylogeography of Chinese dairy goats, we analyzed 162 complete mitochondrial DNA (mtDNA) Dloop sequences from 9 dairy goat breeds and compared them with 8 goat sequences that were previously reported in GenBank. The length of the mtDNA D-loop was 1,212 to 1,215 bp, and 97 polymorphic sites were identified. We also defined 62 haplotypes, including 35 unique haplotypes. The haplotype diversity value of all the dairy goats was 0.952, and the nucleotide diversity was 0.011 per site. Phylogenetic analyses revealed that Chinese dairy goats were divided into haplogroups A and B, with haplogroup A serving as the predominant group. Median-joining network and analyses of molecular variance indicated that Chinese dairy goats were more weakly phylogeographically structured than other domestic goats. A mismatch distribution analysis and Fu’s Fs test revealed that at least 1 population expansion event occurred in the demographic history of Chinese dairy goats.