The Genetic Diversity And Genetic Structure Of The Genus Qinling Subspecies Were Analyzed By MtDNA And Microsatellite

Budorcas taxicolor(Artiodactyla,Bovidae)is distributed in India,Nepal,Bhutan,Burma and China,and includes four subspecies,B.taxicolor taxicolor,B.taxicolor bedfordi,B.taxicolor tibetana and B.taxicolor whitei.B.taxicolor bedfordi,only distributed in Qinling Mountains in Shaanxi Province,is first class nationally protected animals in China,VU level in IUCN and included in the CITES annex II.In view of the endangered of B.taxicolor bedfordi,a number of protected areas were established,many research projects about the individual ecological behavior,breeding and other aspects were carried out,and formulated a series of laws and regulations by government.With these protecting efforts,the populations have increased year by year.However,it is not clear about the basic genetic information whether the genetic diversity and group adaptability were increasing,and inbreeding was appeared.The genetic diversity,population quantity and living habits are important parts in conservation of B.taxicolor bedfordi.This study deals with the genetic variations of 3 B.taxicolor bedfordi population collected from Qinling Mts.by analyses of genetic diversity and genetic structure.We use microsatellite genotype data and mitochondrial D-Loop sequence to survey the genetic diversity,population structure,dispersal model,demographic history dynamics of this subspecies.The results are as follows.1)The complete mitochondrial genome sequence of B.taxicolor bedfordi was determined,assembled and annotated.The total length of mitochondrial genome is 16662bp.The mitogenome contains 13 protein coding genes,22 tRNA,2 rRNA.and a control region.The secondary structure of tRNASer(AGY)lacks DHU arm.Like other mammals,the dominant mismatch of secondary structure is GU mismatch.There are the same protein coding codons between B.taxicolor bedfordi and other Bovidae species.The BI phylogenetic tree showed that the relationship between Ovibos moschatus and B.taxicolor bedfordi is not closely related.They have strong similarity in morphology and behavior may cause by convergent evolution.2)The complete sequence of mtDNA D-Loop region from 76 individuals belonging to 3 populations of B.taxicolor bedfordi were sequenced.The length of D-Loop region is 1053bp.It contains 995 conserved sites,39 singleton variable sites.18 parsimony informative sites and 57 variable sites which occupies 5.50%of the total.There are 21 haplotypes of all D-Loop region from 76 samples and the distribution of the most haplotypes are disordered among three populations,although each population has particular haplotype.From the phylogenetic tree and minimum spanning networks of 21 haplotypes,we can see that B.taxicolor bedfordi have two maternal origins.The average haplotypes genetic distance is 0.008,the haplotypes diversity reaches 0.813,the diversity of nucleotides is 0.00350.The species appeares with low haplotypes genetic distance and nucleotides diversity,which means the low level genetic diversity in B.taxicolor bedfordi population.The Foping population had a closer genetic distance with the Zhouzhi population,while those in Zhouzhi population had a further genetic distance from the Yangxian population.The Tajima's D and Fu's Fs are significant negative,showed that the subspecies have experienced demographic expansion from 15 thousand and 7 hundred years ago in the late Quaternary Period.3)A total of 171 alleles have been detected from 20 microsatellite loci of 76 individual,with 14 loci have null alleles.The frequency of null alleles ranged from-0.404 to 0.357 which can be ignored for subsequent analysis.The average PIC of 20 loci is 0.576 which shows that the 20 loci have middle and upper level diversity and can be applied to analysis of genetic diversity.The highest PIC is P6 loci reached 0.321 and the lowest is P2 loci reached 0.851.The average observed heterozygosity is 0.342,lower than the average expected heterozygosity which was 0.629.All populations revealed significant departures from HWE,with positive value of inbreeding index,indicating the existence of heterozygote deficiencies and low genetic diversity.The BOTTLENECK analysis reveales no genetic evidence for bottleneck effect in all populations.