| The Rhus Gall Aphids (Hemiptera:Aphididae), including six genera and 14 species, parasitize on Rhus to form galls, which are important medical and industrial materials. In this study, the genetic diversity and genetic structure of the Rhus gall aphid Melaphis rhois populations (from North America) and Schlechtendalia chinensis (from China) were examined by analyzing the DNA sequences of the mitochondrial cytochrome c oxidase subunits Ⅰ (COI) and Ⅱ (COII), and cytochrome b (Cytb) genes. The main results are as following:1) We totally obtained 1,522bp DNA sequence in length with combined COI (683bp), COII (406bp) and Cytb (433bp) genes on sampling 32 individuals across three populations of M.rhois and 44 individuals across five populations of S.chinensis. The results revealed considerable variation in 164 nucleotide sites (about 10.8%) with 157 parsimony information sites among the analyzed individuals of M.rhois, which was much more than that among S.chinensis population which included 25 variable sites (about 1.6%) with 20 parsimony information sites. The sequences of both M.rhois and S.chinensis owed high A+T%, and the value of the third site was much higher than the other two sites.2) All the obtained sequences of S.chinensis populations appeared 13 different haplotypes, and the haplotype diversity and nucleotide diversity were 0.860 and 0.00371, respectively, among which the genetic diversity of Guizhou population was the highest one. In case of M.rhois,11 different haplotypes were identified, and the haplotype diversity and nucleotide diversity were 0.867 and 0.03502 respectively, among which the genetic diversity of the New Jersey population was the highest one. Both of the two species appeared lower genetic diversity than other insects. The Guizhou population of S.chinensis and New Jersey population with higher genetic diversity should be mainly conserved.3) The Molecular variance analysis (AMOVA) of S. chinensis showed that the genetic variation within populations were greatly higher than that between populations (Fst=0.2377, P<0.05), meaning that the differentiation existed between populations. The AMOVA of M.rhois showed that the genetic variation between populations were greatly higher than that within populations (Fst=0.7269, P<0.001), so the differentiation was significant between populations of M.rhois. The significant pairwise estimates of genetic distance were detected among the populations of M.rhois (0.0792-0.0819), especially between Ohio and the others, so we speculated that the Ohio population might be regarded as a subspecies of M.rhois. But the values of S.chinensis (0.0026-0.0053) is obviously lower than that of M.rhois.4) The NJ/MP phylogenetic trees and TCS network relationship suggested that there was significant difference among different populations of M.rhois, especially between the Ohio population and the others, whereas five populations of S.chinensis were distributed in different clusters and the branches of clusters were parallel.5) Both neutral examination and mismatch distribution showed that the M.rhois experienced a long evolutionary history in a large stable population, in which isolation by distance might play a significant role on the scale of these investigations. In contrast, the present diversity distribution of S.chinensis might result from a recent population expansion, refuge and populations rebuilding.The Oxya subtribes Acridoidea, Orthoptera, Insecta, is a agricultural pest. Due to the phylogeny of Oxya has not been solved still, in this study, the molecular phylogeny of Oxya were investigated by analyzing the DNA sequences of ribosomal DNA ITS1 sequences (Internal Transcribed Spacer. The main results are as follows:(1) The molecular phylogeny of the Oxya species were investigated by sequencing the rDNA ITS1 sequences. The A、T、C、G content is 19.4%、 21.1%、31.2%、28.2% respectively. GC content is much higher than AT content obviously, which was significantly different from mtDNA sequence.(2) We totally obtained 381bp sequences including 48 variable sites (about 12.6%) with 22 parsimony information site. Nucleotide variation between different individuals ranged from no nucleotide mutation (between O.adentata and O.brachyptera) to 36 nucleotide mutation (between O.intricata and O.agavisa).(3) The phylogenetic tree showed that O.agavisa and O.japonica was closely clustered; the three species O. Chinensis, O.adentata and O.brachyptera have close relationship; O.hainanensis and O.japonica closely clustered; O.intricata was obviously remote from other species, but with lower confidence values. In total, the more markers and samples were necessary to further examine the relationship among Oxya species. |
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