mtDNA haplotype network analysis: Exploring genetic relationships and diversity in dog haplogroups

The genetic diversity and relationships of dog haplogroups were studied by analyzing the HV1 region of mitochondrial DNA. Previous studies have found six distinct haplogroups (A, B, C, D, E, and F) in dogs. Haplogroups A, B, and C were widely distributed, while haplogroups D, E, F were rare and distributed in restricted regions. In this study, HV1 sequences from global dog populations were collected, categorized into haplotypes, and used to construct haplotype networks. The results showed that haplogroup A was the most prevalent, comprising approximately 72.34% of dogs worldwide. Haplogroups A, B, and C together accounted for around 97.40% of the global dog population. Haplogroups D, E, and F were rare, constituting less than 3% of the dog population. Haplogroups E and F made up only about 1-2%. Number of haplotypes in haplogroups D, E, and F were little, sgesting that these haplotypes were introduced into the canine population more recently with limited time for significant mutations. Analysis of haplotype networks showed that haplotypes A were introduced into the dog populations in the early stage of dog domestication. Haplotype Eharbouring dogs were genetically close to wolves, suggesting a recent introduction of haplogroup E. Similarly, haplogroup F exhibited a narrow distribution primarily in Japanese dogs, with haplotype F3 identified as the founder haplotype likely introduced from a few wolves carrying the F3 haplotype.Through the analysis of the haplotype network and assessment of the betweenness value, this study has identified important haplotypes contributing significantly to the dog population. These analyses offer valuable insights into the identification of founder haplotypes involved in the formation of dog breeds worldwide, serving as a valuable reference for breed development and genetic studies.