Benado M B, Ayala F J, Green M M
Genetics. 1976 Jan;82(1):43-52. doi: 10.1093/genetics/82.1.43.
The theory of evolution predicts that the rate of adaptation of a population is a function of the amount of genetic variation present in the population. This has been experimentally demonstrated in Drosophila populations in which genetic variability was increased either by mass hybridization of two gene pools, or by X-irradiation.--Mutator genes increase the spontaneous mutation rates of their carriers. We have now studied the effects of a third-chromosome mutator gene, mt, on the rate of adaptation of laboratory populations. Initially, experimental and control populations had similar genetic constitutions except for the presence of absence of the mt gene. The populations were maintained for 20-25 generations by "serial transfer" under conditions of very intense selection.--The number of flies produced per unit time remained constant throughout the experiment in the experimental as well as in the control populations. However, in the mutator-carring populations the average longevity of the flies (and consequently the average population size) gradually decreased. Under the experimental conditions natural selection is unable to counteract completely the increased input of deleterious mutations due to the mt gene.
进化理论预测，种群的适应速率是种群中存在的遗传变异量的函数。这一点已在果蝇种群中通过实验得到证明，在这些果蝇种群中，遗传变异性通过两个基因库的大规模杂交或X射线照射得以增加。——突变基因会提高其携带者的自发突变率。我们现在研究了位于第三条染色体上的突变基因mt对实验室种群适应速率的影响。最初，实验种群和对照种群除了有无mt基因外，遗传构成相似。通过在非常强烈的选择条件下进行“连续转移”，使这些种群维持了20至25代。——在整个实验过程中，实验种群和对照种群每单位时间产生的果蝇数量保持恒定。然而，在携带突变基因的种群中，果蝇的平均寿命（进而平均种群大小）逐渐下降。在实验条件下，自然选择无法完全抵消由于mt基因导致的有害突变输入的增加。
