The effect of spatial randomness on the average fixation time of mutants

Autor: Natalia L. Komarova, Mohammad Kohandel, Amirhossein H. Darooneh, Moladad Nikbakht, Suzan Farhang-Sardroodi
Přispěvatelé: Tanaka, Mark M
Jazyk: angličtina
Rok vydání: 2017
Předmět:
0301 basic medicine
Population Dynamics
Genetic Fitness
Infographics
Mathematical Sciences
Quantitative Biology::Cell Behavior
0302 clinical medicine
Models
Statistics
Natural Selection
Quantitative Biology::Populations and Evolution
Statistical physics
Cell Cycle and Cell Division
lcsh:QH301-705.5
Randomness
Mathematics
education.field_of_study
Ecology
Population size
Statistical
Biological Sciences
Fixation (population genetics)
Computational Theory and Mathematics
Cell Processes
030220 oncology & carcinogenesis
Modeling and Simulation
Physical Sciences
Probability distribution
Graphs
Research Article
Computer and Information Sciences
Evolutionary Processes
Population Size
Evolution
Bioinformatics
Population
Models
Biological
Skewness
Microbiology
Evolution
Molecular
03 medical and health sciences
Cellular and Molecular Neuroscience
Population Metrics
Information and Computing Sciences
Genetics
Moran process
education
Molecular Biology
Ecology
Evolution
Behavior and Systematics
Evolutionary Biology
Models
Statistical
Population Biology
Data Visualization
Biology and Life Sciences
Computational Biology
Molecular
Bacteriology
Cell Biology
Probability Theory
Probability Distribution
Biological
030104 developmental biology
lcsh:Biology (General)
Biofilms
Mutation
Bacterial Biofilms
Zdroj: PLoS Computational Biology, Vol 13, Iss 11, p e1005864 (2017)
PLoS computational biology, vol 13, iss 11
PLoS Computational Biology
ISSN: 1553-7358
Popis: The mean conditional fixation time of a mutant is an important measure of stochastic population dynamics, widely studied in ecology and evolution. Here, we investigate the effect of spatial randomness on the mean conditional fixation time of mutants in a constant population of cells, N. Specifically, we assume that fitness values of wild type cells and mutants at different locations come from given probability distributions and do not change in time. We study spatial arrangements of cells on regular graphs with different degrees, from the circle to the complete graph, and vary assumptions on the fitness probability distributions. Some examples include: identical probability distributions for wild types and mutants; cases when only one of the cell types has random fitness values while the other has deterministic fitness; and cases where the mutants are advantaged or disadvantaged. Using analytical calculations and stochastic numerical simulations, we find that randomness has a strong impact on fixation time. In the case of complete graphs, randomness accelerates mutant fixation for all population sizes, and in the case of circular graphs, randomness delays mutant fixation for N larger than a threshold value (for small values of N, different behaviors are observed depending on the fitness distribution functions). These results emphasize fundamental differences in population dynamics under different assumptions on cell connectedness. They are explained by the existence of randomly occurring “dead zones” that can significantly delay fixation on networks with low connectivity; and by the existence of randomly occurring “lucky zones” that can facilitate fixation on networks of high connectivity. Results for death-birth and birth-death formulations of the Moran process, as well as for the (haploid) Wright Fisher model are presented.
Author summary We study the influence of randomness on evolutionary dynamics, assuming that a newly arising mutant may experience a different set of environments compared to the wild type. We calculate the mean conditional fixation time of the mutant under different assumptions on spatial interactions, and show that randomness has a strong impact on the fixation time. In particular, it delays the fixation of mutants on 1D circles and accelerates it on complete graphs (the so called mass action, or complete mixing, model). This result holds for advantageous, disadvantageous, and neutral (on average) mutants. The reason for this pattern is quite intuitive: in a rigid, 1D structure, randomness can by chance put a “roadblock” and disrupt mutant spread, causing significant delay. In higher dimensions, there are many ways for a mutant to spread, and it is difficult to block all of them by chance; on the other hand, randomness can enhance fixation by providing an “easier” path. The effects of a random environment are important in biological models such as bacterial growth or cancer initiation/progression.
Databáze: OpenAIRE
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