Abstract
BackgroundAnopheles (Kerteszia) cruzii (Diptera: Culicidae) is a primary vector of human and simian malaria parasites in southern and southeastern Brazil. Earlier studies using chromosome inversions, isoenzymes and a number of molecular markers have suggested that An. cruzii is a species complex.ResultsIn this study, a multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was carried out to investigate in more detail the genetic differentiation between the An. cruzii populations from Florianópolis–Santa Catarina (southern Brazil) and Itatiaia–Rio de Janeiro States (southeastern Brazil). The analyses were performed first comparing Florianópolis and Itatiaia, and then comparing the two putative sympatric incipient species from Itatiaia (Itatiaia A and Itatiaia B). The analysis revealed high FST values between Florianópolis and Itatiaia (considering Itatiaia A and B together) and also between the sympatric Itatiaia A and Itatiaia B, irrespective of their function. Also, using the IM program, no strong indication of migration was found between Florianópolis and Itatiaia (considering Itatiaia A and B together) using all loci together, but between Itatiaia A and Itatiaia B, the results show evidence of migration only in the direction of Itatiaia B.ConclusionsThe results of the multilocus analysis indicate that Florianópolis and Itatiaia represent different species of the An. cruzii complex that diverged around 0.6 Mya, and also that the Itatiaia sample is composed of two sympatric incipient species A and B, which diverged around 0.2 Mya. Asymmetric introgression was found between the latter two species despite strong divergence in some loci.
Highlights
Anopheles (Kerteszia) cruzii (Diptera: Culicidae) is a primary vector of human and simian malaria parasites in southern and southeastern Brazil
Additional file 2: Table S2 shows the number of polymorphic sites (S) for each An. cruzii sibling species and two measures of nucleotide diversity: π, based on the average number of pairwise differences and θ, based on the total number of mutations
Pairwise estimates of population differentiation between the An. cruzii sibling species are shown in Table 1, which shows the average number of nucleotide substitutions per site (Dxy), the number of net nucleotide substitutions per site between species (Da) and the distribution of the four mutually exclusive categories of segregating sites observed in each comparison: the number of exclusive polymorphisms for each species (S1 and S2), the number of shared polymorphisms (Ss) and the number of fixed differences (Sf)
Summary
Anopheles (Kerteszia) cruzii (Diptera: Culicidae) is a primary vector of human and simian malaria parasites in southern and southeastern Brazil. Different studies have been made for identification of Anopheles species complexes, which are virtually identical in adult morphology, but exhibit differences in their malaria transmission competence, resting habitats, host preference and insecticide resistance [3,12,13,14] In this way, many authors have used molecular and genetic data for evolutionary analysis in a number of Anopheles species (An. gambiae, An. fluviatilis, An. funestus, An. barbirostris, An. punctulatus, An. subpictus and others) in an effort to resolve their taxonomic status [2,13,15,16,17,18,19,20,21]. Isoenzymes indicated two genetically isolated groups, one from Bahia State (northeastern Brazil), and the other from southeastern and southern Brazil (Rio de Janeiro, São Paulo and Santa Catarina States) [24] These studies led to further analyses using different molecular markers. This analysis indicated that they probably have not exchanged migrants since their separation, which was roughly estimated to have occurred around 2.4 million of years ago [26]
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