Genetic divergence in mitochondrial DNA of Anopheles nuneztovari (Diptera: Culicidae) from Brazil and Colombia

In the present study, we have examined the variability in Anopheles nuneztovari mitochondrial DNA of three populations from the Brazilian Amazon and one from western Colombia (Sitronela), using four restriction endonucleases (BclI, ClaI, HindIII, SstI). The haplotype diversity (h) was slightly elevated in all populations (0.5000 to 0.6765), whereas the nucleotide diversity (π) was lower in the Sitronela population (0.0029) and higher in populations from the Brazilian Amazon (0.0056 to 0.0098). The degree of sequence divergence (δ) estimated within the Brazilian Amazon and that in Sitronela (0.0329 to 0.0371) suggests that these geographic populations of A. nuneztovari may eventually constitute separate species. The low sequence divergence values among the three Brazilian Amazon populations (0.0012 to 0.0031) indicate that these populations are genetically similar. These results are consistent with those recently reported for allozymes of these same populations

Mitochondrial and ribosomal internal transcribed spacer (ITS2) diversity of the African malaria vector Anopheles funestus

The pattern of sequence variation in the mitochondrial DNA cytochrome b gene (cyt-b) and ribosomal DNA internal transcribed spacer 2 (ITS2) was examined in #Anopheles funestus$from Senegal and Burkina Faso in West Africa and Kenya in East Africa. From both West African countries, samples included individuals hypothesized to represent reproductively isolated taxa based upon different karyotypes and behaviours. Analysis of the cyt-b data revealed high haplotypic diversity (86$ sequences were almost monomorphic, with only two rare polymorphisms detected. The results from both markers are congruent and do not support the hypothesis of reproductively isolated chromosomal taxa within #An. funestus$. Whether the lack of support by mitochondrial DNA (mtDNA) and ribosomal DNA (rDNA) sequences is a result of the recent origin of the presumptive taxa, or of the absence of barriers to gene flow, remains to be elucidated, using more rapidly evolving markers such as microsatellites. (Résumé d'auteur

Program and abstract of the 45th annual Meeting of the American Society of Tropical Medicine and Hygiene

The genetic structure of #Anopheles gambiae$ populations representing extreme geographic scales was studied based on several genetic markers. These scales included houses within a village, villages up to 50km apart, and countries 6000 km away. The following questions were answered : (1) Are mosquitoes in a house more related genetically to each other than mosquitoes in different houses ? (2) What degree of genetic differentiation occurs on these geographic scales ? and (3) How consistent are the results obtained by separate genetic markers ? No differentiation was detected among houses by FST, RST and the band sharing index tests applied to the 5 microsatellite loci. Likewise, indices of kinship based on mtDNA haplotypes in houses were even lower than in the pooled sample. Thus, the hypothesis that mosquitoes in a house are more related genetically was rejected. No subdivision of the gene pool among 4 villages in western Kenya was detected by FST or RST based on the 5 microsatellite loci. Likewise, estimates of haplotype divergence of mtDNA between these villages were not higher than the within population estimates. Significant divergence between populations from Kenya and Senegambia was detected by 3 of the 5 microsatellite loci (average Wright's FST was 0.016 and average Slatkin's RST was 0.036) and by 2 of 6 allozyme loci (average FST was 0.036, calculated based on Miles, 1978). These values are surprisingly low and correspond to an effective migration index (Nm) larger than 3, suggesting gene flow across the continent is only weakly restricted. The concordance between results based on microsatellite loci and mtDNA at the microgeographic levels, and between the allozyme's FST and the microsatellite's RST at the macrogeographical level attested for this description of the population structure. (Résumé d'auteur