MacKay Patricia A, Lamb Robert J, Smith Marjorie A H
Department of Entomology, University of Manitoba, R3T 2N2, Winnipeg, MB, Canada.
Agriculture Canada, 195 Dafoe Road, R3T 2M9, Winnipeg, MB, Canada.
Oecologia. 1993 Jun;94(3):330-338. doi: 10.1007/BF00317106.
Many aphid species have shown remarkable adaptability by invading new habitats and agricultural crops, although they are parthenogenetic and might be expected to show limited genetic variation. To determine if the mode of reproduction limits the level of genetic variation in adaptively important traits, we assess variation in 15 life history traits of the pea aphid, Acyrhosiphon pisum (Harris), for five populations sampled along a north-south transect in central North America, and for three traits for three populations from eastern Australia. The traits are developmental times and rates as affected by temperature, body weights as affected by temperature, fecundity, measures of migratory tendency, and photoperiodic responses. The most southerly population from North America is shown to be obligately parthenogenetic, as are the Australian populations, and the four more northerly North American populations are facultatively parthenogenetic with the number of parthenogenetic generations per year increasing from north to south. The broad-sense heritabilities of life history traits varied from 0.36 to 0.71 for nine quantitive traits based on a comparison of within-and between-lineage variances. Using these traits, 7-13 distinct genotypes (i.e. clones) were identified among each of the 18 lines sampled from the North American populations, but the number did not differ significantly among populations. The level of genetic variation differed from trait to trait. For 4 of 12 quantitative traits, the level of variation in the obligately parthenogenetic population from North America was lowest, but significantly lower than all the sexual populations for only 1 trait. The obligately parthenogenetic population had the highest level of genetic variation for two traits, and had intermediate levels for the others. The most northerly population, which was sexual and had relatively few parthenogenetic generations each year, had the lowest level of variation for 5 of 12 traits and the highest level of variation for 2 traits. There was no decline in variability from north to south correlated with the increase in the annual number of parthenogenetic generations. The Australian populations showed no less variation than the North American populations for two of three traits, although the pea aphid was introduced to Australia only 5 years prior to the study, whereas the aphid has been in North America for at least 100 years. The mode of reproduction has not had a substantial impact on the level of genetic variation in life history traits of the pea aphid, but there are population-specific factors that effect the level of variation in certain traits.
许多蚜虫物种通过侵入新的栖息地和农作物表现出了显著的适应性，尽管它们是孤雌生殖的，并且可能预期会表现出有限的遗传变异。为了确定繁殖方式是否限制了适应性重要性状的遗传变异水平，我们评估了豌豆蚜（Acyrhosiphon pisum (Harris)）15个生活史性状的变异情况，这些性状来自于在北美中部沿南北样带采集的5个种群，以及来自澳大利亚东部的3个种群的3个性状。这些性状包括受温度影响的发育时间和速率、受温度影响的体重、繁殖力、迁移倾向的度量以及光周期反应。来自北美的最南端种群以及澳大利亚种群都表现为专性孤雌生殖，而北美更靠北的4个种群是兼性孤雌生殖，每年孤雌生殖的代数从北向南增加。基于谱系内和谱系间方差的比较，9个数量性状的生活史性状广义遗传力在0.36到0.71之间。利用这些性状，在从北美种群采集的18个品系中的每一个中都鉴定出了7 - 13个不同的基因型（即克隆），但不同种群之间的数量没有显著差异。遗传变异水平因性状而异。在12个数量性状中的4个性状上，来自北美的专性孤雌生殖种群的变异水平最低，但只有1个性状显著低于所有有性生殖种群。专性孤雌生殖种群在2个性状上具有最高的遗传变异水平，在其他性状上则处于中等水平。最靠北的种群是有性生殖的，并且每年的孤雌生殖代数相对较少，在12个性状中的5个性状上变异水平最低，在2个性状上变异水平最高。从北到南，变异程度并没有随着每年孤雌生殖代数的增加而下降。在3个性状中的2个性状上，澳大利亚种群的变异程度并不低于北美种群，尽管豌豆蚜在研究前5年才被引入澳大利亚，而蚜虫在北美已经存在了至少100年。繁殖方式对豌豆蚜生活史性状的遗传变异水平没有实质性影响，但存在种群特异性因素影响某些性状的变异水平。
