The complete mitochondrial DNA D-loop sequences from 10 stud Brahman cattle were sequenced and analyzed. The results showed that the genetic diversity of Brahman cattle was rich ; the rate of nucleotide variation, haplotype diversity and nucleotide diversity were 6.25%, 0.978± 0.054 and 0.014 30± 0.008 68, respectively. Nine haplotypes were defined and fell into two distinct lineages, suggesting that Brahman cattle have both Bos indicus （Zebu） and B. taurus genetic background. The taurine haplotypes were predominant at 90% and only Brah-6 belonged to the Asian zebu mthaplotype. This indicates that Brahman cattle was one of the zebu breeds and inherited the excellent characteristics of both the Asian zebu and European beef cattle, such as easy calf delivery, high quality beef, heat tolerance and resistance to various parasites. Breeders introduced Brahman cattle to improve the productivity and adaptability of native cattle. The Zebu has evidently frequently introgressed into the modem taurine breeds. As for modem zebu breeds, B. taurus also highly contributed to their formation, except for the Asian zebu. Furthermore our results also confirm the hypothesis that B. indicus has undergone a separate domestication event and originated from the Indian subcontinent.
Although the Suidae animals were one of the most prosperous mammals, their taxa and phylogeny were poorly studied. To bridge this research gap, the complete mitochondrial DNA cyt b sequences （1140 bp）of one red river pig （ Potamochoerus porcus ）, one bearded pig （ Sus barbatus ）, and several Eurasian wild boars （ Sus scorfa ） were determined with direct PCR sequencing method. Incorporated with the sequences of other Suidae species obtained from GenBank, the phylogentic trees of Suidae species were constructed by Neighbor-Joining and Most Parsimony method. Our resuits showed that the babirousa was sister group of all other species. The African species clustered into a single clade, while the Eurasian species formed the other clade. The phylogenetic positions of the Sus species were consistent with their geographical distribution. Based on our phylogeographical results, the Sus species could be classified into three groups： （1） the relatively primitive animals from Philippine Islands （such as S. cebifrons and S. philippensis ）, Sulawesi and it＇s adjacent islands （S. celebensis）, （2） the Eurasian wild boars （S. scrofa and the mysterious S. salvanius）, and （3） other pigs （such as S. barbatus and S. verrucosus）, which might further diverged as the islands type （such as S. barbatus from Sumatra and Borneo） and the continental type （such as Malay Peninsula wild boar）.
