A Percolation Lattice of Natural Selection as a Switch of Deterministic and Random Processes in the Mutation Flow
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USSIONS
A Percolation Lattice of Natural Selection as a Switch of Deterministic and Random Processes in the Mutation Flow A. Ya. Garaevaa, *, A. E. Sidorovaa, N. T. Levashovaa, and V. A. Tverdislova aDepartment
of Physics, Moscow State University, Moscow, 119991 Russia *e-mail: [email protected]
Received December 28, 2019; revised December 28, 2019; accepted February 10, 2020
Abstract—This review considers the basic models of mutation processes that occur during selection and drift. A basically new model was developed to describe the mutation flow through a percolation lattice of selection at the population level. Natural selection of optimal variants in the evolutionary flow of mutations was considered as a percolation filter, which acts as a physical tool that forms the mechanism of selection. The model was based on the concepts of self-organization in hierarchical structures of speciation, where the trigger properties of a cell (node) as a valve determine the deterministic component of the fixation of new mutations and the drift adds the element of randomness to the fixation of new mutations in mutation flows. Modes of mutation fixation were identified depending on the ratio of the cluster size of mutation carriers to the total size of the population and the selection and drift coefficients in a sequence of generations at the population level. A lower threshold of the percolation selection lattice was determined as the share of new mutations fixed under the influence of deterministic selection processes for a minimum reproducing cluster size. Keywords: natural selection, self-organization, fluctuations, bifurcation, percolation, prohibiting and permitting mutations DOI: 10.1134/S0006350920030069
INTRODUCTION Modeling of mutation processes during selection and drift is commonly based on analyzing the mutations that belong to the same type [1, 2] and that exert a mostly beneficial effect [1, 3–6]. Interactions between mutations decrease the likelihood of fixation for beneficial mutations. As an example, interactions with deleterious mutations [7] might abolish the effect of beneficial mutations [1, 4, 8], and interactions between beneficial mutations may decelerate the adaptation process and reduce the average effect of the beneficial mutations [9]. In total, clonal interference between mutations is possible for mutations with various effects [10] and is more likely at a greater population size and a higher mutation rate [11]. The distribution of beneficial mutations has variously been associated with the effects of pleiotropy [12, 13], Hill– Robertson [14], Muller’s ratchet [15], reverse mutations [16], and epistasis (e.g., epistasis may facilitate recombination or not in populations under sexual selection [17–20]). All of these factors accelerate or slow the fixation of beneficial mutations in certain conditions. New mutations often arise in clones, and clonal dominance provides an advantage to the mutation, especially when persisting for a long period of time [21, 22]. However, Timofeev-Ressovsky [23] showe
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