Molecular Systematic Study On Several Genera Of Myrmicinae (Hymenoptera :Formicidae) From Guangxi

The ant is a typical social insects which belong to the family Formicidae of the Order Hymenoptera. Based on the statistics, the recorded ants in the world include 16 subfamilies, 296 genera, 9538 species. Ants, with some 15,000 estimated species in all over the world, form a large group of animals that are dominant in most terrestrial ecosystems and important in the study of evolutionary biology because of the high expression of their social behavior. The study takes Guangxi ants as objects, by sequencing technic ,getting about 851bp DNA sequences of 12 species of 7 genera of the subfamily Myrmicinae,the entire sequences include the partial CO1 gene and CO2 gene and integral tRNAleu gene. Analyzing these data with software (including MEGA,DNASP,Phylip) and discussing the kinship and class status of the 7 genera in the Guangxi province with theories, methods and viewpoints of the molecular systematic, revealing the phylogeny and evolution of them. The results of this study provide some new information and science spectacles for molecular systematic, enriching and perfecting Myrmicinae molecular systematic, settling a basement for the studying molecular systematic of ants in Guangxi province of China. Partial sequences are reported for the mitochondrial genes for cytochrome oxidase subunits 1 and 2 and the entire sequences of the gene for tRNAleu for twelve species from seven genera of Myrmicinae ants. The sequences obtained are 851bp in average length and contain 24.25% G+C and 75.75% A+T and represent the character of AT biased that according to that of other insects. Basing on the outcomes of analysis of the nucleotide composition; the nucleotide diversity; the Synonymous and the nonsynonymous; the transition and the transvertion; the phylogeny, those indicate the evolution rate of CO1 gene is faster than that of CO2 gene. All kinds of these study results, including analyzing the nucleotide composition, the amino acid composition, the nucleotide diversity, the synonymous and the nonsynonymous, the transition and the transvertion, the frequencies of the codon used, the construction (including four stems and four loops) of tRNAleu,the phylogeny,suggest that great distinctness present among the genera and small difference even none among species. According to the information and proof from every aspect, the conclusion of phylogeny is drew to that one small clade is Tetramo + Myrmica; the other small clade is Pheidole + Pristomyrmex; the third small clade is Pheidolo + Aphaeno; the big clade is consist of above all three small clade; the calde of Cremato locate the side of this big clade. From originality to evolution, the order is Pheidolo>Cremato>Pristomyrmex>Tetramorium>heidole>Myrmica>Aphaeno;or probably Pheidolo > Cremato > Pristomyrmex > Aphaeno > Tetramorium > Pheidole >Myrmica. The results of this study infer that CO1 gene ,CO2 gene and tRNAleu gene fit in studying phylogeny and evolution in the relation of genus, but misfit in studying phylogeny and evolution in the close kinship relation of groups. If the study question refer to the relation of genus besides the relation of species, Which require to select and consider more suitable gene, such as Cytb gene, because the evolution rate of this gene is faster than that of CO1 gene,CO2 gene. These questions would be further studied and confirmed. The study gets some meaningful information by analyzing constructions of tRNAleu gene, which implies that the study should develop from the low-grade constructions to the high-grade constructions; from the genes to the functions of the gene; from the interior constructions and mechanism to the surface characters and features; which is the trend for the development of the molecular systematic, the same as that the traditional phylogeny developed from the macrocosm to the microcosm ago. With studying deeply and extensively, molecular would, and should develop from the macrocosm to the microcosm. The macrocosm and the microcosm will promote and benefit each other. Additionally, sampling correctly and logically, getting more useful and meaningful information, including nucleotide sites, amino acid sites, by means of the diverse methods and measures; basing on all sorts of theories and evidences and results, and so on, which will benefit for probing and discussing problems, discovering and elucidating principles and laws, making the study develop deeply and extensively.