Department of Infection, Immunity, and Inflammation, Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, 75014 Paris, France.
Mol Cell. 2019 Aug 8;75(3):421-425. doi: 10.1016/j.molcel.2019.06.029.
Mutation rates affect both a population's present fitness and its capacity to adapt to future environmental changes. When the available genetic variability limits adaptation to environmental change, natural selection favors high mutations rates. However, constitutively high mutation rates compromise the fitness of a population in stable environments. This problem may be resolved if an increase in mutation rates is limited to times of stress, restricted to some genomic regions, and occurs only in a subpopulation of cells. Such within-population heterogeneity of mutation rates can result from genetic, environmental, and stochastic effects. The presence of subpopulations of transient mutator cells does not jeopardize the overall fitness of a population under stable environmental conditions. However, they can increase the odds of survival in changing environments because they represent reservoirs of increased genetic variability. This article presents evidence that such heterogeneity of mutation rates is more the norm than the exception.
突变率既影响种群当前的适合度，也影响其适应未来环境变化的能力。当可用遗传变异性限制了对环境变化的适应时，自然选择有利于高突变率。然而，高突变率会降低稳定环境中种群的适合度。如果突变率的增加仅限于压力时期，限制在某些基因组区域，并仅发生在细胞的亚群中，则可以解决这个问题。这种种群内突变率的异质性可能是由遗传、环境和随机因素引起的。在稳定的环境条件下，短暂突变体细胞亚群的存在不会危及种群的整体适合度。然而，它们可以增加在变化环境中生存的几率，因为它们代表了遗传变异性增加的储备库。本文提供的证据表明，这种突变率的异质性更常见而不是例外。
