| Ants is typical insect and belong to Formicidae, Hymenoptera. According to the statistics, 9538 species, 296 genera of 16 subfamilies are recorded in the world. Ants, with some 20,000 estimated species in the whole world, form a large group of animals that are dominant in most terrestrial ecosystems. And the high expression of their social behavior is very important for the study of evolutionary biology.There are two parts in this thesis.The first part is a morphological systematic study on Chinese species of the ant genus Tetramorium Mayr. In this part there are 47 species are treated, among them five species are new to science, i. e. T. oligobarbus sp. n., T. sculptipetiolum sp. n., T. scrupireticulum sp. n., T. ocellus sp. n., and T. kraepelinioides sp. n., and the descriptions of them were added; The pictures of them are attached; A key to 47 Chinese species of Tetramorium is presented.The second part is a molecular systematic study on 4 species of 15 colonies of the ant genus Myrmica Latreille. In this reearch, the Cytb, COâ… &COâ…¡gene sequences were amplified by Touchdown PCR, and the sequences which have obtained were analyzed by software (including ContigExpress, tRNAscanSE1.21, ClustalX1.83, MEGA4, PAUP4, Dnasp4). According to the analyses of Cytb, COI, COâ…¡and Cytb+COI+COâ…¡gene sequences, we reconstructed the phylogenetic relationships of these species by using Neighbor-Joining (NJ), Maximum Parsimony (MP) and Maximum Likelihood (ML). The conclusions are showed as follows:The A+T contents of Cytb, COI, COâ…¡and Cytb+COI+COâ…¡genes of 15 in Myrmica and 7 species in outgroups are 73.1%, 76.0%, 72.7% and 74.6%, respectively, while the G+C content of them are 26.8%, 24.0%, 24.9% and 25.4%, which shows a strong A+T bias. Though analyse of codon, we found the bias in codon usage of the 22 species sequences. In my study, 19 kinds of amino acids (besides Cys) are coded in Cytb and COI genes, and 20 in COâ…¡and Cytb+COI+COâ…¡genes, and there are strong biases in amino acids contents.To these 22 colonies sequences, transitions are the same with transversions, or less than transversion. Most transitions occur between T and C, while most transversions occur between A and T. Substitution of the second position of colons are the lowest: transition are 10.8%, 14.3%, 9.5% and 10.8% of all transition, respectively, while transversion are 8.1%, 15%, 9.1% and 8.9%. And Substitutions of the third position of colons are the highest: transitions are 67.6%, 57.1%, 64.3% and 64.5%, while transversions are 67.6%, 55.0%, 68.2% and 65.3%.By reconstructing the phylogenetic tree of 15 colonies in Myrmica and 7 species in outgroups is reconstructed. The topologies of the trees are almost identical. The result shows that the genus Myrmica is a monophyletic group. The phylogenetic relationships of 22 species (including outgroups) in genus Myrmica indicate: M. sp. and M. ruginodis form one sister group, while M. jessensis and M. pisarkii form anther sister group, and then the two sister groups make up of the Myrmica monophyletic group. They are separate from outgroups perfectly. But there is a problem in different geographical gourps. The results support the views of that dividing the Myrmica ruginodis into two groups.Sequence divergences within these ants indicate that Cytb, COI, COâ…¡and Cytb+COI+COâ…¡is useful marker in phylogenetic study at species and geographical gourp levels.
|
PDF Full Text Request