Mitochondrial DNA detects a complex evolutionary history with Pleistocene Epoch divergence for the neotropical malaria vector Anopheles nuneztovari sensu lato

Abstract

Cryptic species and lineages characterize Anopheles nuneztovari s.l. Gabaldón, an important malaria vector in South America. We investigated the phylogeographic structure across the range of this species with cytochrome oxidase subunit I (COI) mitochondrial DNA sequences to estimate the number of clades and levels of divergence. Bayesian and maximum-likelihood phylogenetic analyses detected four groups distributed in two major monophyletic clades (I and II). Samples from the Amazon Basin were clustered in clade I, as were subclades II-A and II-B, whereas those from Bolivia/Colombia/Venezuela were restricted to one basal subclade (II-C). These data, together with a statistical parsimony network, confirm results of previous studies that An. nuneztovari is a species complex consisting of at least two cryptic taxa, one occurring in Colombia and Venezuela and the another occurring in the Amazon Basin. These data also suggest that additional incipient species may exist in the Amazon Basin. Divergence time and expansion tests suggested that these groups separated and expanded in the Pleistocene Epoch. In addition, the COI sequences clearly separated An. nuneztovari s.l. from the closely related species An. dunhami Causey, and three new records are reported for An. dunhami in Amazonian Brazil. These findings are relevant for vector control programs in areas where both species occur. Our analyses support dynamic geologic and landscape changes in northern South America, and infer particularly active divergence during the Pleistocene Epoch for New World anophelines.

Figure 1.

Geographic distribution of Anopheles nuneztovari s.l. (larger shaded area) and An. dunhami (smaller shaded area), and the collection sites of these species in northern South America. See Table 1 for locality abbreviations.

Figure 2.

Parsimony network of the 52 haplotypes observed in Anopheles nuneztovari s.l. H1–H52 = haplotypes. The number of individuals observed in each haplotype is next to the locality abbreviation. Empty smaller circles represent mutational events. See Table 1 for locality abbreviations.

Figure 3.

Bayesian Inference (BI) topology of the 59 haplotypes of Anopheles nuneztovari s.l. and Anopheles dunhami inferred under the TPM2uf + I + G model. Numbers on each branch represent posterior probabilities in BI (above branch) and bootstrap proportions in ML (below branch). Anopheles darlingi was used as outgroup.

Figure 4.

Estimated geographic distributions of clade I and subclades II-A, II-B, and II-C of Anopheles nuneztovari s.l. See Table 1 for locality abbreviations.

Figure 5.

Observed mismatch distributions among haplotypes in Anopheles nuneztovari s.l. for clade I, three subclades, and combined data. Bars are observed distribution, and the line shows the distribution simulated under a sudden expansion model.