Characteristics Of Mitochondrial Genome Of Eld's Deer (Cervus Eldii) And Phylogenetic Position In The Phylogeny Of The Cervidae According To Analysis Of Complete Mitochondrial Genome Sequences

We sequenced the complete mitochondrial (mt) genome of Eld's deer (Cervus eldii) by polymerase chain reaction. Characteristies of mitoehondrial gneome of Cervus eldii are summarized as following. The complete mt genome was 16 357 base pairs in length and included the typical 22 tRNA, two rRNA, and 13 protein-coding genes(PCGs), and a non-coding control region. The H strand of Cervus eldii mt genome consist of 33.19% A,24.81% C,15.28% G,30.88% T bases, which indicated that the bases showed a compositional bias. Adenines and cytosines were preferentially used in third codon positions of PCGs of Cervus eldii, a similar degree of codon bias was also observed in the mt genome of Cervus nippon. However, the codons that contain adenines and thymine in the third codon position were overused compared to other synonymous codons in PCGs of other cervids under consideration. And there was an anti-G bias in third codon positions and pyrimidines were overrepresented in second codon positions. Our results showed that all Ka/Ks ratios were well below one, indicating that purifying selection was the predominant force in mtDNA evolution. However, the Ka/Ks ratios among different gene families were variable in 13 PCGs, suggesting that differential selective constraints act on them. The CO1 gene showed the lowest Ka/Ks rates in all PCGs, which suggests that there was greater functional constraint on COX proteins, while the ATP8 gene showed a significantly high Ka/Ks rate, which suggests that ATP8 has evolved faster than any of the other PCGs. ATG was used as a start codon for all of the PCGs, with the exceptions of ND2, ND3, and ND5, which started with ATA. ATP6, ND3, and ND4 ended on an incomplete stop codon T and CO3 on TA, COB ended on AGA, and ND2 ended on TAG, whereas the other seven genes ended on the usual TAA stop codon.The phylogenetic position of Eld's deer within the Cervidae was determined by analyses of 12 of the 13 protein-coding sequences, with the exception of the gene NADH6. Our maximum likelihood and Bayesian inference results split Cervidae into plesiometacarpal (Cervinae + Muntiacinae) versus telemetacarpal (Odocoileinae + Hydropotinae) conditions, and suggested paraphyly of antlered deer. And also our data confirmed the basal clade of Eld's deer in Cervus and monophyly of Cervus nippon and supported monophyly of Cervus elaphus.