In silicoexperiments uncover a novel mechanism underlying mutation rate evolution in sexually reproducing populations

Abstract

Natural selection is believed to universally work to lower mutation rates (MR) due to the negative impact of mutations on individual fitness. Mutator alleles have only been found to be co-selected by genetic linkage with adaptive alleles in prokaryotes. Sexual reproduction substantially reduces genetic linkage, allowing selection to effectively eradicate mutator alleles. The current understanding, therefore, is that in sexually reproducing populations selection always works to lower MR, limited by the effective population size that determines the overall selection efficiency. In the present paper, we apply a Monte Carlo model of a sexually reproducing population and demonstrate that selection acting on MR does not universally favor lower MR but depends on the mode of selection acting on adaptive phenotypic traits. We demonstrate a unique previously unreported co-selective process that can drive the evolution of higher MR in sexually reproducing populations. Our results show that MR evolution is significantly influenced by multigenic inheritance of both MR and adaptive traits that are under selection. Our results also show that, contrary to the generally accepted axiom, population size appears not to affect the strength of selection uniformly but likely forms an intra-population gradient that generates a "biased sampling" process that has an opposite effect on selection strength and thus modulates or even negates the effect of population size on MR evolution. Based on our results, we propose an expanded population genetics theory of the evolution of mutation rates in sexually reproducing organisms. Our results have potential implications for understanding processes underlying rapid adaptive change in speciation and related macroevolutionary patterns

Fungal Strains with Identical Genomes Were Found at a Distance of 2000 Kilometers after 40 Years

“…Because of the negative impact of most mutations on individual adaptability, natural selection is considered to be generally effective in reducing mutation rates (MR). Limited by population size, sexual reproduction will always lead to a decrease in MR, thus maintaining the stability of the genome [85][86][87]. By comparing the genomes of parents and the offspring, it was found that some species have very stable genomes [1,88,89].…”