Striking allelic diversity despite structural homogeneity of ace-1 duplications in Anopheles mosquitoes

A. gambiae s.l. has been the target of intense insecticide treatment since the mid-XXth century to try and control malaria, and a substitution in the ace-1 locus allowing resistance to organophosphate and carbamates insecticides has been rapidly selected for. Since then, several duplications of the ace-1 locus have been found in A. gambiae s.l. populations. They associate either several resistance copies (homogeneous duplications) or both resistance and susceptible copies (heterogeneous duplications). Heterogeneous duplications confer an intermediate trade-off between resistance in presence of insecticide and disadvantage in their absence. So far, and in striking contrast with C. pipiens mosquitoes, a single heterogeneous duplication had been describe in A. gambiae populations. We use an innovative approach, combining information from long and short read sequencing with Sanger sequencing to precisely identify and describe at least nine different heterogeneous duplications in A. gambiae. We further show that these alleles share the exact same structure than the previously identified heterogeneous and homogeneous duplications, namely 203-kb tandem amplifications with conserved breakpoints. Our study sheds a new light on the origin and maintenance of these alleles in A. gambiae populations, and pushes one step further the striking evolutionary convergence with C. pipiens mosquitoes.