| Domesticated horse was one of the essential livestocks raised by human beings.Domesticated horses have been firstly used for meat production,riding and labour animals and also used for entertainments,and even meat and milk for thousands of years.The origin of horse domestication is always an interesting issue and evoked many related studies from the aspects of archaeology and molecular biology.Besides mtDNA and autosomal sequences,study on ECAY(Equus Caballus Y chromosome,ECAY)will provide us new insights into paternal contritions to the origin of horse domestication.In the present stduy,domestication origin of Chinese indigenous horses was studied using both mtDNA and ECAY genetic variations and results were displayed as follow:(1)Abundant maternal diversity was found in CHBs,and nucleotide and haplotype diversity in NC was higher than that in SC(2)18 reported mtDNA haplotype group were found in CHBs except B1.This was the first time that C2 and A2 were detected in CHBs.What’s more,H and I two newly identified haplotype groups were added into mtDNA median joining network.Horese in H and I were mainly from SC and they were the important evidence indicating a domestication event in SC.(3)ECAY median joining network showed distinct paternal genetic difference between CHB and European horses.Ancestral HT1 group found in European horses mutated into the main ECAY haplotype groups in CHB with two nucleotide variants.(4)FST values indicated most closed genetic relationships between NC and SC horses,CHBs and AT or Arab horses,CHB and ancient Kazakhstan horses.FST also showed that there was no close relationship between CHBs and horses in Europe or Iberia Peninsula.(5)Mismatch distribution analysis using mtDNA indicated that nearly all populations underwent demographic expansion.In contrast,mismatch distribution analysis using ECAY variations showed population demography expansion only in SWG,GXG and TG horses.(6)Estimation of stallion numbers in initial domesticated populations showed that there might be nearly 31 stallions involved in Chinese domestication.In conclusion,(1)domesticated horses in Middle Asia may had spred into China and exerted much influnce on horse domestication in China.However,NC and SC horses experienced different domestication progress resulting from different geographic enviroment and historic factors.(2)Population structure resluts using mtDNA variations indicated multiple maternal origin in CHBs.A clear domestication has undergone in SC and domesticated horses were limited and conserved in SC which showed the domestic horses in the ancient China were not exclusively introduced.(3)ECAY network indicated two base pair difference between the prominent haplotypes of CHB and European horses.CHT groups might come from ancient HT1 found in European horses.(4)SC was the Noah’s Ark of horse genetic diversity by keeping most diversified genetic variations. |
