DNA Barcoding Of Some Predatory Beetles In The Areas Around Beijing And Tianjin

The main content of this thesis includes two sections: 1) to construct DNA barcoding data of predatory beetles in the areas around Beijing and Tianjin; 2) to identify three morphologically indistinguishable species through DNA barcodes.1) the experimental materials include 3229 specimens of 168 species belonging to 74 genera of 17 families in the areas around Beijing and Tianjin which were obtained from investigations on diversity of species and identification.(1) through molecular biology technology, we successfully obtained 1734 COI sequences, 970 of which were not identified morphologically;(2) we recorded detailed information of each specimen(code, classification information, specimen information, collection records, COI sequence information and specimen photos, etc.), which was used to construct a relatively complete predatory beetle resources data with various species and full biological records;(3) The statistics of the effective sequence of the species in each family were carried out and the phylogenetic trees were constructed, respectively. By clustering analyses of NJ tree, most unidentified specimen were identified successfully. In total, 1595 COI sequences belonging to 216 species, 81 genera, 14 families were obtained. Then, Caribidae, followed by Meloidae and Cantharidae, contained the most sequences. What’s more, the factors affecting the DNA extractions were analyzed and they were killing methods, preservation conditions and time, particularity of beetle exoskeleton, sampling, primer specificity, and so on.(2) three species belonging to the genus Epicauta(Coleopera: Meloidae), E. sibirica, E. dubia, and E. chinensis, appear morphologically indistinguishable and have common distribution areas. The deep taxonomic study for them was carried out through DNA barcoding. Taking 4 meloid species as outgroups, analyses of nucleotide composition, genetic distances and phylogenetics were performed on partial fragments of the mitochondrial gene(COI) of 77 samples. Combined with the adult morphological characters among the three species, we conclude that E. dubia(Fabricius, 1781) and E. chinensis(Laporte, 1840) should be regarded as two synonyms of E. sibirica(Pallas, 1773).