Maternal Origin And Genetic Diversity Of Chinese Domestic Buffalo

China is one of the countries that have the richest swamp buffalo resources in the world ,it has been domesticate and selected for 7000 years, which belonged swamp buffalo. Because of lacking comprehensive and systematic knowledge on the genetic diversity and characteristics of indigenous buffalo types, we only used the native breeds as the female parents and the foreign breeds as the male parents to hybrid, which has led to the decline of the genetic diversity of buffalo gradually and even the distinct of some genetic resource of buffalo soon. For we do not had a complete and deep knowing the domestic and genetic diversity of the China buffalo, to protect and use the domestic buffalo genetic resource perfectly, Through analyzing the mtDNA D-loop of 455 samples from 22 Chinese indigenous buffalo types, we studied the maternal origin of the buffalos, the phylogenetic relations between genetic varieties and diversity and got these results as follows:1. The length of the complete mtDNA D-loop sequences varied from 894bp to 920 bp in 455 individuals of 22 Chinese buffalo types. Most is 916 bp, this is because there are three special polyG/C in the complete sequence.2. 114 sites are polymorphic in 148 hyplotypes with 12.36% of 915 bp D-loop region, 97 of these sites are transitions,12 of them are transvertions, 5 of these sites have both transitions and transvertions. it is suggesting that the base bias which is in proportion to mammalian mitochondrial DNA nucleotide composition. The haplotype diversity and nucleotide diversity were 0.4000±0.2373～1.0000±0.1265 and 0.0070±0.0 039～0.0219±0.0116, respectively, indicating abundant genetic diversity in Chinese buffalo populations.3. NJ phylogenetic and a reduced median network analysis in Chinese buffalo mtDNA revealed two highly divergent, namely lineages A and B. which suggested that Chinese native buffalo may have two maternal origins. The lineage B also divided two bio-lineage, we first called them B1 and B2.4. There is poor population structure among 22 Chinese buffalo types. All the China buffalo types had two lineages, poor genetic difference. But in the lineages, types/population had the obvious difference, little variation; also the lineage B as the older lineage is deeper than the lineage A.5. There happened two population expansion events in Chinese swamp buffalo. Mismatch distributions of lineages A,B1 and B2. showed one peak, also Fs values were -26.32(P<0.01), -21.09 (P<0.01) and -13.27(P<0.01), respectively, which suggested Chinese buffalo lineage A underwent population expansion events, and lineage A did a larger one. And lineage B shows two peak -24.73(P<0.01)which suggestes lineage B has underwent two smaller population expansion events.