The Genetic Diversity Analysis And The Primary Study Of Subspecies Differentiation Of Tree Sparrows

Tree sparrow(Passer montanus) is a widespread and human commensal species. However,the studies of tree sparrow have been rare in our country since the 1980s,especially in the aspect of molecular biology methods.In this paper,the genetic diversity and subspecies differentiation of tree sparrows were preliminarily studied,expecting to provide more information for further researches.There are two parts in this paper.In the first part,the genetic diversity of 62 tree sparrows of Hebei Province were determined by analyzing the mitochondrial DNA D-loop partial gene sequence.In the second part,the subspecies differentiation was preliminarily analyzed by measuring mitochondrial Cyt b gene sequences of 15 tree Sparrows from four areas of our country.The main conclusions are as follows:1.The average length of mtDNA D-loop gene partial sequences is 741 nucleotides.The A+T content of whole sequence(57%) is higher than the G+C content of whole sequence (43%).32 variable sites are detected accounting for 4.44%,including 6 parsimony informative sites and 26 singleton variable sites.2.MEGA software were used to analyze mtDNA D-loop gene sequences.The values of the nucleotide diversity and the haplotype diversity are 0.0021±0.0004 and 0.755±0.057, respectively.Compared with other reported,both of the value of the nucleotide diversity and haplotype diversity are lower.22 haplotypes were observed in the 32 variable sites.The results of phylogenetic analysis based on haplotypes indicate there are no phenomenons of evolution divergence.3.The mismatch distribution was a better fit to unimodal curve and Fu's Fs test of neutrality including the result deviated from neutral mutation.This result could confer that population expansion had happened in tree sparrow passer evolution history.4.The average length of mtDNA Cyt b gene entire sequences is 1143 nucleotides.The A, T,G and C accounts for 27.0%,22.9,14.8%and 35.3%in average nucleotide sequence, respectively.The A+T content of all sequences is 41.8%while the G+C content is 58.2%.The content of pyrimidine is higher than the content of purine.There are large divergences in the utilization rate of synonymy codon. 5.In 15 mtDNA Cyt b gene entire sequences,9 miss/insert sites,1110 conservative site, 24 variable sites,7 parsimony informative sites and 17 singleton variable sites were checked. Transition frequency was higher than transversion frequency.The value of R was 2.0.Therein, nucleotide substitution frequency of the first and second site in codon was lower far from saturation.whereas the third site in codon reached saturation.6.The average value of all sequences was d=0.004 based on Jukes-Cantor method. Therefore,p-distance could indicate genetic distance.The genetic distance of populations and sequences were 0.0038～0.0058 and 0～0.010,respectively.The result analyzed by using of the method of non parameter Tajima in MEGA software showed that the main emtranchments of nucleotide substitution velocity were same and had relatively invariable molecular clock. Therefore,the differentiation time of the tree sparrow was conferred in 0.19～0.29Ma.