Inversion monophyly in African anopheline malaria vectors

Area of Science:

• Genetics
• Evolutionary Biology
• Entomology

Background:

• The Anopheles gambiae complex comprises six sibling species with significant chromosomal inversions.
• Previous phylogenetic inferences based on the Xag inversion suggested A. gambiae and A. merus as sister taxa.
• Recent DNA data conflict, proposing A. gambiae and A. arabiensis as sister taxa.

Purpose of the Study:

• To investigate the monophyly of the Xag inversion in the Anopheles gambiae complex.
• To reconcile conflicting phylogenetic data derived from chromosomal inversions and DNA sequences.
• To explore the role of introgression in shaping the genetic landscape of Anopheles species.

Main Methods:

• Analysis of a soluble guanylate cyclase gene located within the Xag inversion.
• Comparison of genetic data with existing phylogenetic hypotheses.
• Investigation of potential introgression patterns across the Anopheles genome.

Main Results:

• Data from the soluble guanylate cyclase gene strongly support the monophyly of the Xag inversion.
• The findings suggest that previously observed DNA phylogenies may reflect introgression rather than true evolutionary relationships.
• Introgression appears to be non-uniform across the genome, with chromosomal inversions potentially undergoing selective elimination.

Conclusions:

• The Xag inversion is likely monophyletic, challenging previous phylogenetic interpretations.
• Introgression between sympatric species, particularly A. gambiae and A. arabiensis, is a plausible explanation for conflicting phylogenetic signals.
• Genomic regions like X-chromosome inversions may resist introgression due to selection against hybrids.