title: Independent duplications of the acetylcholinesterase gene conferring insecticide resistance in the mosquito Culex pipiens.
abstract: 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.
authors.affiliation: Institut des Sciences de l'Evolution (UMR CNRS 5554), University Montpellier II, Montpellier, France.
authors.forename: Pierrick
authors.initials: P
authors.lastname: Labbé
authors.forename: Arnaud
authors.initials: A
authors.lastname: Berthomieu
authors.forename: Claire
authors.initials: C
authors.lastname: Berticat
authors.forename: Haoues
authors.initials: H
authors.lastname: Alout
authors.forename: Michel
authors.initials: M
authors.lastname: Raymond
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenormand
authors.forename: Mylène
authors.initials: M
authors.lastname: Weill
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics*; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D009033:Culicidae / Q000201:enzymology / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons / Q000235:genetics; D005260:Female; D020440:Gene Duplication; D005787:Gene Frequency; D014644:Genetic Variation; D006239:Haplotypes; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007438:Introns / Q000235:genetics; D008297:Male; D008957:Models, Genetic; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors
chemical_list: D019476:Insect Proteins; D000110:Acetylcholinesterase