To assess the genetic diversity between randomly and selectively bred populations,we sequenced 438 bp of the mitochondrial DNA control region from 102 pigs.These samples represented four native pig breeds,one nucleus ...To assess the genetic diversity between randomly and selectively bred populations,we sequenced 438 bp of the mitochondrial DNA control region from 102 pigs.These samples represented four native pig breeds,one nucleus and one conservation herd from Yunnan,China.Twenty haplotypes with sixteen polymorphic sites were identified.The number of haplotypes in the nucleus herd of Saba pig and the conservation herd of Banna miniature pig were restricted to three and one,respectively,while the randomly bred pig populations exhibited over six haplotypes.Notably,haplotype diversity in randomly bred populations was significantly greater than the selectively bred populations（h=0.732 vs.0.425 and 0,exact test,P≤0.0036）.These findings demonstrate that selective breeding generated low genetic diversity compared to randomly bred pig breeds.A timely intervention and well programmed breeding approach would stop further genetic diversity reduction in the nucleus and conservation herds of native pig breeds.Otherwise,selective breeding would dramatically reduce genetic diversity in only several years,indicating that sharp contradictions exist between breeding,conservation and genetic diversity.Genetic relationships are discussed based on net genetic distances among pig populations.展开更多
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, hap...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.展开更多
基金supported by research grants of the National Basic Research Program of China (2007CB815700 2006CB102100)Bureau of Science and Technology of Yunnan Province, and Natural Science Foundation of China (30621092)
文摘To assess the genetic diversity between randomly and selectively bred populations,we sequenced 438 bp of the mitochondrial DNA control region from 102 pigs.These samples represented four native pig breeds,one nucleus and one conservation herd from Yunnan,China.Twenty haplotypes with sixteen polymorphic sites were identified.The number of haplotypes in the nucleus herd of Saba pig and the conservation herd of Banna miniature pig were restricted to three and one,respectively,while the randomly bred pig populations exhibited over six haplotypes.Notably,haplotype diversity in randomly bred populations was significantly greater than the selectively bred populations（h=0.732 vs.0.425 and 0,exact test,P≤0.0036）.These findings demonstrate that selective breeding generated low genetic diversity compared to randomly bred pig breeds.A timely intervention and well programmed breeding approach would stop further genetic diversity reduction in the nucleus and conservation herds of native pig breeds.Otherwise,selective breeding would dramatically reduce genetic diversity in only several years,indicating that sharp contradictions exist between breeding,conservation and genetic diversity.Genetic relationships are discussed based on net genetic distances among pig populations.
文摘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.
