| Phlebotomus chinensis Newstead,1843 belongs to Family Psychodidae, Subfamily Phlebotominae, Genus Phlebotomus. P. chinensis is distributed widely in China, as one of important visceral leishmaniasis vector in distribution regions. Some research results showed that it was different in morphology, bionomics and vector energy among geographic localities. And there is doubt about its classification status for several years in some regions. So it is necessary to study on the classification status and population genetic structure of P. chinensis in China.The outline of this research was as below. First, we collected sandfly adults of P. chinensis in several distribution regions from China. Second, we used morphologic characters and molecular markers to distinguish P. chinensis from other sandfly species. Third, polymorphic microsatellite loci of P. chinensis were screened and their characters were studied. Finally, the mtDNA-Cytb gene and microsatellite loci were used to analyze the gene flow, gene introgression, the level on genetic diversity and population divergence of P. chinensis in China. The results were as follows:1. We collected P. chinensis samples from six positions in four provinces, as Henan, Shanxi, Sichuan and Gansu. The collecting positions were cover from different geographic environments, ecological habits and altitude level. We also collected P. sichuanensis species samples from type locality (Jiuzhaigou, Sichuan, above altitude level on 2000m), P. wui and P. longiductus from Xinjiang.2. We observed 132 individuals of P. chinensis from different positions,26 of P. sichuanensis,29 of P. wui and 23 of P. longiductus. The identification morphologic characters in P. wui and P. longiductus were sure and obviously, but it was a little difference between P. chinensis and P. sichuanensis, with the wing length and the ratio of female and male.3. Genomic DNA of single sandfly was extracted from P. chinensis, P. sichuanensis and P. wui samples, which were distinguished by morphology. The rDNA-ITS2 and mtDNA-Cytb region were amplified and sequenced. The equences alignment showed that there was not inter-specific distinction among three sandflies based on ITS2 in this study. The inter-specific distinction by Cytb was better than ITS2 sequences. There were considerable significant differences between P. chinensis and P. sichuanensis in molecular markers, and genetic divergence among P. chinensis populations. It was suggested that the P. sichuanensis remains temporary was reasonable. The relationship of P. chinensis with P. sichuanensis was very closely, P. sichuanensis should be in speciation processing.4. The 118 microsatellite sequences of P. chinensis were identified in 154 positive clones. Twenty-two loci were chosen to screen the polymorphism, and 14 loci were polymorphic. Meanwhile,10 loci of them were gene scanned, and their characters were studied.5. The mtDNA-Cytb gene and 10 microsatellite loci were used to study the population genetic structure. The results of two molecular markers showed that there was the highest degree of genetic variance within Henan population, Fst was negative between two Shanxi populations and their divergence was minimal. The general trend was that the level of gene flow was negative related with geographic distances; the pattern of population genetic structure was accord with isolation-by-distance model. The value of gene flow was 0.0594, and there was a high level of genetic divergence among populations, which was positive related with geographic distances closely based on mtDNA-Cytb gene. However, based on microsatellite DNA, the gene flow was 6.599, and there was low level of genetic divergence among populations, the degree of divergence was closely related sandfly species, and also with the geographic distances. The results of microsatellite loci should be more realistic situation by comprehensive estimates.
|
PDF Full Text Request