Study On Genetic Differentiation Of Four Species Of Turdidae Birds

We used ND2 and CO1 genes in mitochondrial DNA and 13 microsatellite loci to research the genetic diversity,genetic structure and genetic differentiation of Naumann's Thrush(Turdus naumanni),Dusky Thrush(Turdus eunomus),Red-throated Thrush(Turdus ruficollis)and Black-throated thrush(Turdus atrogularis)to investigate the effects of introgression on the four species of birds.Combined with the morphological characteristics,the classification status of the four species of birds was redefined.The main results were as follows:1.The phylogenetic tree(BI and ML)based on ND2 and CO1 genes showed that.naumanni and T.eunomus were clustered together,T.ruficollis and.atrogularis were clustered,and the two clades were monophyletic,and they are closely related to.torquatus.The phylogenetic tree(UPGMA)based on microsatellite loci also showed that T.naumanni and T.eunomus were closely related and had the farthest relationship with T.atrogularis.Using BP&P analysis,the species formation rate of group T.naumanni and group T.ruficollis was 1 under each parameter,while the rates of species formation between T.naumanni and T.eunomus,Truficollis and Tatrogularis were less than 0.99 under some certain parameters.The results of the principal component analysis scatter plot constructed using five quantifiable morphological indicators were consistent with the phylogenetic analysis results.Combined with a variety of species definition methods,it was recommended to define T.eunomus as the northern subspecies of T.naumanni(Turdus naumanni eunomus)and T.atrogularis as the T.ruficollis black-throated subspecies(Turdus ruficollis atrogularis).2.The Analysis of Molecular Variance(AMOVA)was used to test the genetic differentiation levels of four species of birds and to calculate the gene flow.The combination of ND2 and CO1 genes in mitochondrial DNA showed a high level of gene flow between T.n.eunomus and T.n.naumanni(4.678),and T.r.ruficollis and T.r.atrogulari also had high levels of gene flow(Inf),while other populations showed low levels of gene flow with obvious genetic differentiation(0.0063-0.0086).Based on the micro sate llite DNA,gene flow the four species of birds showed that the range of gene flow between species was 3.12-Inf.There were high levels of gene flow among the species.The levels of gene flow between subspecies are higher than that between species(20.86-inf>3.12-7.79).The gene flow analysis of four species of birds showed that there were introgression at the mitochondria and microsatellite levels among the subspecies,and the introgression at the microsatellite level between species.Introgression is caused by incomplete reproductive isolation between species and overlapping areas of large areas.3.The genetic diversity index indicated that the T.r.atrogulari population(without hybrids)had the highest nucleotide diversity(0.00645±0.00203);the T.n.naumanni population had the lowest(0.00311±0.00034).When containing hybrids,the T.r.atrogulari population had the highest nucleotide diversity(0.00948±0.00181);the T.n.naumanni population had the lowest(0.00435±0.00061).It indicated that introgression increased the genetic diversity of the four species of birds.