Study Of Numt Sequences Among Birds

Mitochondrial DNA as a genetic marker has been successfully applied to the study of molecular evolution of birds, but the research of mitochondrial pseudogene— numt sequences among birds are still very rarely. The numt sequences, after the first discovery in The 1960s, were valued by researchers until the beginning of 90s. Now, Numts have been extensive researched in different species including plants, insects and mammals.Numt usually were preferential amplified by usual primers from total DNA, examination of avian cytb of GenBnk, we found 5 numts that be thinked for mitochondrial gene, numts in fact. Furthermore, the research put forward that gene functional positions can effective identify numts.Three major clusters of numt sequences ( cyt b numt, ATP8+ATP6 numt and ND4+ tRNA-His+ tRNA-Ser numt) were particularity amplified and sequenced from 10 species within Galliformes and A.galericalata. Comparison numts sequences with homologous mitochondrial partial genes get the different evolutionary characteristics and evolutionary speed compared to mtDNA, then examine the age of insertion of numts using the sequence divergence of numt from the mtDNA. Finally, joined Coturnix japonica, Coturnix chinensis, Lophura leucomelana, Lophura swinhoii and A.albifrons mitochondrial sequences in GenBank, we study the importance function to phylogenetic research of mitochondrial genes and homologous numts.The evolutionary rate of Numts is lower than their authentic sequences of mtDNA, cyt b and ND4 gene evolve faster than homologous numts 2.5 times; ATP8+ATP6 gene evolve faster than numts 18.9 times in Galliformes. Numts show less codon position bias and transition bias under not phylogenetic pressure. We examined the divergence of three numts including cyt b numt, ATP8+ATP6 numt and ND4+ tRNA-His+ tRNA-Ser numt and get the age of insertion of numts: 16Myr, 16.5Myr and4.2 Myr ago. Maximum-parsimony (MP) and Neighbor-joining (NJ) phylogenetic trees were constructed using mitochondrial cyt b partial gene, cyt b numt and ATP8+ATP6 partial gene and numt, respectively. We found that numt is not suitable for phylogenetic relationship on genus level, but very suitable for family level. In Galliformes, numtsuccessfully resolve phylogenetic relationship of species on subfamily level.