Guillemaud Thomas, Lenormand Thomas, Bourguet Denis, Chevillon Christine, Pasteur Nicole, Raymond Michel
Institut des Sciences de l'Evolution, Laboratoire Génétique et Environnement (C.C. 065), UMR CNRS 5554, Université de Montpellier II, F-34095 Montpellier, France.
Evolution. 1998 Apr;52(2):443-453. doi: 10.1111/j.1558-5646.1998.tb01644.x.
Fixation of adaptive mutations in populations is often constrained by pleiotropic fitness costs. The evolutionary pathways that compensate such fitness disadvantages are either the occurrence of modifier genes or replacement of the adaptive allele by less costly ones. In this context, 23 years of evolution of insecticide resistance genes in the mosquito Culex pipiens from southern France are analyzed. The aim of this study is to answer the following points. Is there a fitness cost associated with these resistance genes in natural populations? Does evolution proceed through allele replacement or through selection of modifiers? And finally, how do environmental changes affect the evolution of resistance genes? Samples from the same transect, crossing the boundary between an insecticide-treated and a nontreated area, are analyzed. Clinal analyses indicate a variable fitness cost among the resistance genes and show that allele replacement has been the primary mechanism of resistance evolution in this area. It is also shown that replacement was probably due to environmental changes corresponding to modification in pesticide-treatment intensity.
群体中适应性突变的固定常常受到多效性适合度代价的限制。补偿这种适合度劣势的进化途径要么是修饰基因的出现，要么是用代价较小的等位基因取代适应性等位基因。在此背景下，对法国南部尖音库蚊中杀虫剂抗性基因23年的进化进行了分析。本研究的目的是回答以下问题。在自然群体中，这些抗性基因是否存在适合度代价？进化是通过等位基因取代还是通过修饰基因的选择进行的？最后，环境变化如何影响抗性基因的进化？对来自同一横断面、跨越杀虫剂处理区和非处理区边界的样本进行了分析。渐变分析表明抗性基因之间存在可变的适合度代价，并表明等位基因取代是该地区抗性进化的主要机制。研究还表明，取代可能是由于与农药处理强度变化相对应的环境变化所致。
