Estimation of divergence time between two sibling species of the Anopheles (Kerteszia) cruziicomplex using a multilocus approach

Abstract

BackgroundAnopheles cruzii is the primary human Plasmodium vector in southern and southeastern Brazil. The distribution of this mosquito follows the coast of the Brazilian Atlantic Forest. Previous studies indicated that An. cruzii is a complex of cryptic species.ResultsA multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was implemented to investigate in more detail the genetic differentiation between the An. cruzii populations from Santa Catarina (southern Brazil) and Bahia States (northeastern Brazil) that represent two sibling species. The analysis revealed very high FST values and fixed differences between the two An. cruzii sibling species in all loci, irrespective of their function. An Isolation with Migration model was fit to the data using the IM program. The results reveal no migration in either direction and allowed a rough estimate of the divergence time between the two sibling species.ConclusionsPopulation genetics analysis of An. cruzii samples from two Brazilian localities using a multilocus approach confirmed that they represent two different sibling species in this complex. The results suggest that the two species have not exchanged migrants since their separation and that they possibly diverged between 1.1 and 3.6 million years ago, a period of intense climatic changes.

Speciation in Brazilian Atlantic Forest Mosquitoes: A Mini-Review of the Anopheles cruzii Species Complex

“…Figure 3 shows the posterior probability distributions for each of the three parameters estimated using the IM program. The results suggested that the two species have not exchanged migrants since their separation and that they possibly diverged between 1.1 and 3.6 million years ago (Rona et al, 2010a). In fact, the divergence time between the southern and northeastern species fall within the Pleistocene, a period of intense climatic changes (Cantolla, 2003;Ravelo et al, 2004).…”

“…cruzii, a multilocus analysis was carried out comparing Itaparica to Florianópolis (Rona et al, 2010a). The aim of this study was to determine if there is still gene flow between the two sibling species and to estimate their divergence time.…”

“…The optimal recombination-filtered block was extracted from each gene alignment using the IM GC program, which also removes haplotypes that represent likely recombinant sequences (Woerner et al, 2007). See Rona et al (2010a) for more details. (Modified from Rona et al, 2010a).…”

“…We used a number of single-copy genes to investigate the molecular differentiation and gene flow among the putative sibling species of this complex (Rona et al, 2009(Rona et al, , 2010a. The results and the main conclusions of these analyses are discussed in more detail below.…”

Caracterização molecular e morfológica de Anopheles cruzii e Anopheles homunculus (Diptera; Culicidae) da Mata Atlântica do Estado de São Paulo.

“…O gene COI se mostrou extremamente polimórfico para a espécie Anopheles cruzii e nota-se uma estruturação populacional quando comparados morro e planície. Devido a sua importância como vetor de Plasmodium, o status taxonômico dessa espécie tem sido investigado por vários estudos recentes (Ramirez, Dessen, 2000a, b;Rona et al, 2009Rona et al, , 2010a. Para os autores, as diferenças genéticas e cromossômicas encontradas podem indicar o início de uma especiação dentro de An.…”