Zamoum T, Simon J-C, Crochard D, Ballanger Y, Lapchin L, Vanlerberghe-Masutti F, Guillemaud T
Equipe Biologie des Populations en Interaction, UMR 1112, INRA Antibes 06606, France.
Heredity (Edinb). 2005 Jun;94(6):630-9. doi: 10.1038/sj.hdy.6800673.
The typical life cycle of aphids includes several parthenogenetic generations and a single sexual generation (cyclical parthenogenesis), but some species or populations are totally asexual (obligate parthenogenesis). Genetic variability is generally low in these asexually reproducing populations, that is, few genotypes are spread over large geographic areas. Both genetic drift and natural selection are often invoked to account for this low genetic variability. The peach-potato aphid, Myzus persicae, which encompasses both cyclical and obligate parthenogens, has developed several insecticide resistance mechanisms as a consequence of intense insecticide use since the 1950s. We collected asexually reproducing M. persicae from oilseed rape and examined genetic variability at eight microsatellite loci and three insecticide resistance genes to determine whether their genetic structure was driven by drift and/or selection. We identified only 16 multilocus microsatellite genotypes among 255 individuals. One clone, which combined two insecticide resistance mechanisms, was frequently detected in all populations whatever their location over a large geographical area (the northern half of France). These unexpected findings suggest that drift is not the unique cause of this low variability. Instead, the intensification of both insecticide treatments and oilseed rape cultivation may have favored a few genotypes. Thus, we propose that selective pressures resulting from human activities have considerably modified the genetic structure of M. persicae populations in northern France in a relatively short period of time.
蚜虫的典型生命周期包括几个孤雌生殖世代和一个有性生殖世代（周期性孤雌生殖），但有些物种或种群完全进行无性生殖（专性孤雌生殖）。在这些进行无性生殖的种群中，遗传变异性通常较低，也就是说，很少有基因型分布在广大的地理区域。遗传漂变和自然选择常被用来解释这种低遗传变异性。桃蚜（Myzus persicae）兼具周期性孤雌生殖和专性孤雌生殖类型，自20世纪50年代以来，由于大量使用杀虫剂，它已形成了多种抗药性机制。我们从油菜中采集了进行无性生殖的桃蚜，检测了8个微卫星位点和3个抗杀虫剂基因的遗传变异性，以确定其遗传结构是否受漂变和/或选择的驱动。在255个个体中，我们仅鉴定出16种多位点微卫星基因型。有一种克隆体结合了两种抗杀虫剂机制，无论其位于法国大片地理区域（法国北半部）的何处，在所有种群中都经常被检测到。这些意外的发现表明，漂变并非这种低变异性的唯一原因。相反，杀虫剂处理和油菜种植的强化可能有利于少数基因型。因此，我们认为人类活动产生的选择压力在相对较短的时间内极大地改变了法国北部桃蚜种群的遗传结构。
