Characterization of the complete mitogenome of Anopheles aquasalis, and phylogenetic divergences among Anopheles from diverse geographic zones

Abstract

Whole mitogenome sequences (mtDNA) have been exploited for insect ecology studies, using them as molecular markers to reconstruct phylogenies, or to infer phylogeographic relationships and gene flow. Recent Anopheles phylogenomic studies have provided information regarding the time of deep lineage divergences within the genus. Here we report the complete 15,393 bp mtDNA sequences of Anopheles aquasalis, a Neotropical human malaria vector. When comparing its structure and base composition with other relevant and available anopheline mitogenomes, high similarity and conserved genomic features were observed. Furthermore, 22 mtDNA sequences comprising anopheline and Dipteran sibling species were analyzed to reconstruct phylogenies and estimate dates of divergence between taxa. Phylogenetic analysis using complete mtDNA sequences suggests that A. aquasalis diverged from the Anopheles albitarsis complex ~28 million years ago (MYA), and ~38 MYA from Anopheles darlingi. Bayesian analysis suggests that the most recent ancestor of Nyssorhynchus and Anopheles + Cellia was extant ~83 MYA, corroborating current estimates of ~79-100 MYA. Additional sampling and publication of African, Asian, and North American anopheline mitogenomes would improve the resolution of the Anopheles phylogeny and clarify early continental dispersal routes.

Fig 1. Organization and gene features of the A. aquasalis mitochondrial genome.

Fig 2. The complete mitogenome of A. aquasalis.

BRIG visualization showing the protein coding genes, rRNAs and tRNAs in the mtDNA genome of A. aquasalis. The black inner ring shows the GC content on the outer surface, whereas AT content is shown on the inner surface. Strand asymmetry of the mitogenome is shown by the GC (+) and (-) skews according to the color key shown in the legend.

Fig 3. By-geographic region phylogeny of representative Anopheles, using the concatenated DNA sequences of all the mitochondrial protein coding genes.

The values on the nodes correspond to the posterior probabilities supporting the tree topology. The phylogenetic tree was reconstructed using the concatenated PCGs and the Bayesian Markov Chain Monte Carlo approach (MCMC) analysis implemented in BEAST v1.7.5.

Fig 4. Phylogenetic tree of selected Anopheles using the concatenated DNA sequences of all the mitochondrial protein coding genes.

The values on the tree nodes correspond to the mean divergence time (MYA) estimated for each event. The bars illustrate the 95% credibility intervals of the divergence times. (Table 2 presents the selected key divergence events).