Berticat Claire, Boquien Grégoire, Raymond Michel, Chevillon Christine
Laboratoire Génétique et Environnement, Institut des Sciences de l'Evolution (UMR CNRS 5554), Université de Montpellier II (C.C. 065), F-34095 Montpellier, France.
Genet Res. 2002 Feb;79(1):41-7. doi: 10.1017/s001667230100547x.
Resistance to organophosphorus insecticides (OP) in Culex pipiens mosquitoes represents a convenient model for investigating the fitness cost of resistance genes and its origin, since both the environmental changes in nature and the adaptive genes are clearly identified. Two loci are involved in this resistance--the super-locus Ester and the locus Ace.1--each displaying several resistance alleles. Population surveys have shown differences in fitness cost between these resistance genes and even between resistance alleles of the same locus. In order to better understand this fitness cost and its variability, the effects of these resistance genes on several fitness-related traits are being studied. Here, through competition experiments between two males for the access to one female, we analysed the effect on paternity success associated with three resistance alleles--Ester4, Ester1 and Ace.1R--relative to susceptible males and relative to one another. The eventual effect of female genotype on male mating success was also studied by using susceptible and resistant females. The strains used in this experiment had the same genetic background. Susceptible males had a mating advantage when competing with any of the resistant males, suggesting a substantial cost of resistance genes to this trait. When competing against susceptible males, the paternity success did not vary among resistant males, whatever the genotype of the female. When competing against other resistant males, no difference in paternity success was apparent, except when the female was Ester1.
致倦库蚊对有机磷杀虫剂（OP）的抗性是研究抗性基因的适合度代价及其起源的一个便利模型，因为自然界中的环境变化和适应性基因都已明确。这种抗性涉及两个基因座——超级基因座酯酶（Ester）和基因座乙酰胆碱酯酶1（Ace.1）——每个基因座都有多个抗性等位基因。种群调查显示，这些抗性基因之间，甚至同一基因座的抗性等位基因之间，在适合度代价上存在差异。为了更好地理解这种适合度代价及其变异性，正在研究这些抗性基因对几个与适合度相关性状的影响。在此，通过两只雄蚊竞争与一只雌蚊交配的实验，我们分析了与三个抗性等位基因——Ester4、Ester1和Ace.1R——相关的父权成功情况，以易感雄蚊作为对照，并比较这三个抗性等位基因之间的情况。还通过使用易感和抗性雌蚊，研究了雌蚊基因型对雄蚊交配成功的最终影响。本实验中使用的品系具有相同的遗传背景。易感雄蚊在与任何抗性雄蚊竞争时都具有交配优势，这表明抗性基因对这一性状有很大的代价。当与易感雄蚊竞争时，无论雌蚊基因型如何，抗性雄蚊之间的父权成功率没有差异。当与其他抗性雄蚊竞争时，除雌蚊为Ester1型外，父权成功率没有明显差异。
