Evolution of Gene Regulatory Networks by Fluctuating Selection and Intrinsic Constraints
Authored by Masakado Kawata, Masaki E Tsuda
Date Published: 2010
DOI: 10.1371/journal.pcbi.1000873
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Abstract
Various characteristics of complex gene regulatory networks (GRNs) have
been discovered during the last decade, e. g., redundancy, exponential
indegree distributions, scale-free outdegree distributions, mutational
robustness, and evolvability. Although progress has been made in this
field, it is not well understood whether these characteristics are the
direct products of selection or those of other evolutionary forces such
as mutational biases and biophysical constraints. To elucidate the
causal factors that promoted the evolution of complex GRNs, we examined
the effect of fluctuating environmental selection and some intrinsic
constraining factors on GRN evolution by using an individual-based
model. We found that the evolution of complex GRNs is remarkably
promoted by fixation of beneficial gene duplications under unpredictably
fluctuating environmental conditions and that some internal factors
inherent in organisms, such as mutational bias, gene expression costs, and constraints on expression dynamics, are also important for the
evolution of GRNs. The results indicate that various biological
properties observed in GRNs could evolve as a result of not only
adaptation to unpredictable environmental changes but also non-adaptive
processes owing to the properties of the organisms themselves. Our study
emphasizes that evolutionary models considering such intrinsic
constraining factors should be used as null models to analyze the effect
of selection on GRN evolution.
Tags
Escherichia-coli
Saccharomyces-cerevisiae
Adaptive evolution
Copy number variation
Transcriptional regulation
Hierarchical
structure
Microbial genomes
Pelvic reduction
Duplicate genes
Null
mutations