Independent Duplications of the Acetylcholinesterase Gene Conferring Insecticide Resistance in the Mosquito Culex pipiens

• Published in: Molecular biology and evolution Vol. 24; no. 4; pp. 1056 - 1067
• Main Authors: Labbé, Pierrick, Berthomieu, Arnaud, Berticat, Claire, Alout, Haoues, Raymond, Michel, Lenormand, Thomas, Weill, Mylène
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.04.2007; Oxford University Press (OUP)
• Subjects: Acetylcholinesterase - genetics; Alleles; Animals; Aquatic insects; Base Sequence; Biochemistry, Molecular Biology; Biodiversity and Ecology; Culex pipiens; Culicidae - enzymology; Culicidae - genetics; Environmental Sciences; Evolution, Molecular; Evolutionary biology; Exons - genetics; Female; Gene Duplication; Gene Frequency; Genetic Variation; Haplotypes; Insect Proteins - genetics; Insecticide Resistance - genetics; Insecticides; Introns - genetics; Life Sciences; Male; Models, Genetic; Molecular biology; Mosquitoes; Phylogeny; Sequence Analysis, DNA; Sequence Homology, Nucleic Acid; Time Factors; Culex pipiens; ace-1; insecticide resistance gene; selection; duplication; mosquito; Insecticide resistance gene; Culexpipiens
• ISSN: 0737-4038; 1537-1719
• DOI: 10.1093/molbev/msm025

Gene duplication is thought to be the main potential source of material for the evolution of new gene functions. Several models have been proposed for the evolution of new functions through duplication, most based on ancient events (Myr). We provide molecular evidence for the occurrence of several (at least 3) independent duplications of the ace-1 locus in the mosquito Culex pipiens, selected in response to insecticide pressure that probably occurred very recently (<40 years ago). This locus encodes the main target of several insecticides, the acetylcholinesterase. The duplications described consist of 2 alleles of ace-1, 1 susceptible and 1 resistant to insecticide, located on the same chromosome. These events were detected in different parts of the world and probably resulted from distinct mechanisms. We propose that duplications were selected because they reduce the fitness cost associated with the resistant ace-1 allele through the generation of persistent, advantageous heterozygosis. The rate of duplication of ace-1 in C. pipiens is probably underestimated, but seems to be rather high.