| In recent years, the numbers of mitochondrial (mt) genomes of insects increased rapidly. Moreover, mt-genome was considered as an important molecular marker in the phylogenetic analysis, which has been employed to reconstruct the phylogenetic relationships among order, suborder, superfamily, family, subfamily and other different taxonomic levels. Phylogenetic relationships of Lygaeoidea (Insecta: Hemiptera:Heteroptera) are still controversial, and previous studies mostly based on the morphological characters and few genes. Therefore, it is necessary to reconstruct the phylogenetic relationships of family groups within Lygaeoidea based on mt-genomes. Based on the revised classification system of Lygaeoidea by Henry (1997), this superfamily contained15families. However, there were only4mt-genomes of4families reported within Lygaeoidea before the present study. Herein, by using long PCR and primer walking,15mt-genomes of12families of Lygaeoidea (only lack the representative of Cryptorhamphidae) and other3mt-genomes of heteropterans were sequenced. This dissertation consisted of the following three parts:(A). Combined with other48heteropterans mt-genomes from GenBank and other databases, by using bioinformatics methods, the following results were drawn after comparative studies on these mt-genomes:1. The length of Kleidocerys resedae resedae (Panzer) mt-genome is14,688bp, which is the shortest among all available heteropterans, mainly because of its short control region (220bp).2. The unusual intergenic spacers (38bp-239bp) between tRNA-His and ND4were found in most families of Lygaeoidea, which were only shared by some groups of Lygaeoidea.3. Gene rearrangements were seldom reported in heteropterans mt-genomes. However, one novel gene rearrangement (from trnW-trnC-trnY to trnY-trnW-trnC) was found in the mt-genome of Plinthisus hebeiensis Zheng. Furthermore, two long intergenic spacers were observed beside the gene rearrangement region, which could be elucidated with the tandem duplication-random loss (TDRL) model.4. In the control region of Panaorus albomaculatus (Scott) mt-genome, the unusual52repeats were found in this tandem repeats region.5. Tetranucleotide TAAT was inferred to be the initiation codon of ND5gene in mt-genome of Dimorphopterus japonicus (Hidaka) and Ninomimus flavipes (Matsumura).(B). When the surprising phylogenetic results conflict with the traditional hypotheses of phylogenetic relationships, it should be necessary to test and alleviate the effects of long-branch attraction (LBA) even if these results of the clades have high support values. In the phylogenetic analysis of Nepomorpha by Hua et al.(2009) based on mitochondrial genomes, Nepomorpha is not a monophyly, which conflicted with most previous studies. Besides, they elevated the Pleoidea to a new infraorder, the Plemorpha. After reanalysis the phylogenetic relationships of Nepomorpha based on mt-genomes by adding more data of closely related ingroups and outgroups, all analyses significantly and consistently supported the monophyly of Nepomorpha, which indicated that the results of Hua et al.(2009) might stem from LBA and likely resulted from inadequate taxon sampling.(C). Phylogenetic analyses of Lygaeoidea were based on15mt-genomes of12families of Lygaeoidea from this study combined with other heteropterans mt-genomes from GenBank. This study was followed the classification system of Lygaeoidea by Henry (1997), and carried out by using Maximum likelihood (ML) and Bayesian inference (BI) methods. The following results were obtained:1. Lygaeoidea is a monophyletic group baesd on the phylogenetic analyses of Pentatomomorpha by adding15newly sequenced mt-genomes of Lygaeoidea.2. Heterogastridae is the sister group of Pachygronthidae, and this monophyletic group located at the basal clade of Lygaeoidea.3. Rhyparochromidae is a paraphyletic group, the subfamily Plinthisinae should be taken out to make Rhyparochromidae as a monophyletic group as indicated by Xie et al.(2005) based on the sequences of18rDNA. 4. The Ischnorhynchinae, Lygaeinae, and Orsillinae are united as a monophyletic group, which supported the monophyly of Lygaeidae. The Lygaeinae and Orsillinae are supported as a sister group.5. The monophyletic group "malcid line" is not supported by mt-genomes, especially Colobathristidae is hypothesized as the sister group to some other families of Lygaeoidea.6. Cymidae and Ninidae are unied as a monophyletic group, which agree with the result of Xie (2004, PhD dissertation, based on the sequences of18S rDNA) that did not suggest the raise of Cyminae and Nininae to family level.7. The Geocorinae and Henestarinae form a monophyletic group supported by mt-genomes, the monophyly of Geocoridae is confirmed, which disagree with Gao (2010PhD dissertation) that suggested the spliting of Geocoridae based on morphological characters... |
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