Maximum Likelihood Estimation of the Evolutionary Distance of Complete Genomes of Mitochondrial DNA between Human and 16 Animals

Abstract

The mitochondrial DNA of vertebrates generally has same structure and functions, even share same numbers of genes, tRNAs, rRNAs and codon regions with different sequences in a narrow range of genome size. The resource of database was downloaded from the Genbank of National Center for Biotechnology Information (NCBI), and using a particular computational program to achieve the best results of alignment and statistical calculations to estimate the transition/ transversion in the nucleotide and amino acid substitution, additionally, estimate the evolutionary distance rate between Human versus 16 animals. The results of maximum likelihood method show high rates of substitutions mainly from adenine and thymine to cytosine and guanine (A=>C; A => G; T => C; T => G), respectively. Guanine (G) was the most conserved and stable nucleotide from changes in all over 17 organisms that may be related to the strength of the chemical bonds. The observation of evolutionary distance by the number of substitutions per site between sequences is shown for all three codon positions and non-codon regions. The scores put organisms in groups by comparing the numbers between pairs of sequence within difference and similarity, such as the human, chimpanzee, and gorilla had less distance among them, whilst, a remarkable likelihood between bison and the water buffalo were observed despite the historical and geographical distance between them. Additionally, studying the effect of substitution scores in nucleotide and amino acids on the synonymous/non-synonymous codon substitution in evolutionary distance bias was discussed. Keywords: