# Mitochondrial Variation in Anopheles gambiae and Anopheles coluzzii: Phylogeographic Legacy and Mitonuclear Associations With Metabolic Resistance to Pathogens and Insecticides

## TL;DR

This study explores mitochondrial DNA variation in two malaria-carrying mosquitoes, revealing evolutionary patterns and links to resistance against pathogens and insecticides.

## Contribution

The study provides new insights into mitonuclear coevolution and mitochondrial roles in metabolic resistance in Anopheles mosquitoes.

## Key findings

- Mitochondrial DNA phylogeny shows reticulated evolution and discordance with the species tree in Anopheles gambiae complex.
- A distinct mitochondrial lineage in An. coluzzii is associated with nuclear SNPs linked to pathogen and insecticide resistance.
- Saltwater-tolerant species form a monophyletic group, suggesting introgression and selection shaped mitochondrial evolution.

## Abstract

Mitochondrial DNA has been a popular marker in phylogeography, phylogeny, and molecular ecology, but its complex evolution is increasingly recognized. Here, we investigated mitochondrial DNA variation in Anopheles gambiae and Anopheles coluzzii, in relation to other species in the Anopheles gambiae complex, by assembling the mitogenomes of 1,219 mosquitoes across Africa. The mitochondrial DNA phylogeny of the Anopheles gambiae complex was consistent with previously reported highly reticulated evolutionary history, revealing important discordances with the species tree. The three most widespread species (An. gambiae, An. coluzzii, and Anopheles arabiensis), known for extensive historical introgression, could not be discriminated based on mitogenomes. Furthermore, a monophyletic clustering of the three saltwater-tolerant species (Anopheles merus, Anopheles melas, and Anopheles bwambae) in the Anopheles gambiae complex also suggested that introgression and possibly selection shaped mitochondrial DNA evolution. Mitochondrial DNA variation in An. gambiae and An. coluzzii across Africa revealed significant partitioning among populations and species. A peculiar mitochondrial DNA lineage found predominantly in An. coluzzii and in the hybrid taxon of the African “far-west” exhibited divergence comparable to the interspecies divergence in the Anopheles gambiae complex, with a geographic distribution matching closely An. coluzzii's geographic range. This phylogeographic relict of the An. coluzzii and An. gambiae split was associated with population and species structure, but not with the rare Wolbachia occurrence. The lineage was significantly associated with single nucleotide polymorphisms in the nuclear genome, particularly in genes associated with pathogen and insecticide resistance. These findings underline potential mitonuclear coevolution history and the role played by mitochondria in shaping metabolic responses to pathogens and insecticides in Anopheles.

Graphical abstract
Anopheles gambiae. Credit IRD - Patrick Landmann, Vectopôle, Montpellier.

Anopheles gambiae. Credit IRD - Patrick Landmann, Vectopôle, Montpellier.