An interplay of resource availability, population size and mutation rate potentiates the evolution of metabolic signaling

Bhaskar Kumawat,Ramray Bhat

doi:10.1186/s12862-021-01782-0

Abstract

BackgroundAsexually reproducing populations of single cells evolve through mutation, natural selection, and genetic drift. Environmental conditions in which the evolution takes place define the emergent fitness landscapes. In this work, we used Avida—a digital evolution framework—to uncover a hitherto unexplored interaction between mutation rates, population size, and the relative abundance of metabolizable resources, and its effect on evolutionary outcomes in small populations of digital organisms.ResultsOver each simulation, the population evolved to one of several states, each associated with a single dominant phenotype with its associated fitness and genotype. For a low mutation rate, acquisition of fitness by organisms was accompanied with, and dependent on, an increase in rate of genomic replication. At an increased mutation rate, phenotypes with high fitness values were similarly achieved through enhanced genome replication rates. In addition, we also observed the frequent emergence of suboptimal fitness phenotype, wherein neighboring organisms signaled to each other information relevant to performing metabolic tasks. This metabolic signaling was vital to fitness acquisition and was correlated with greater genotypic and phenotypic heterogeneity in the population. The frequency of appearance of signaling populations increased with population size and with resource abundance.ConclusionsOur results reveal a minimal set of environment–genotype interactions that lead to the emergence of metabolic signaling within evolving populations.

Highlights

Reproducing populations of single cells evolve through mutation, natural selection, and genetic drift
Upper bounds on population size have been suggested to play a contextual role in evolution: small populations are more susceptible to random genetic drift with frequent fixation of deleterious mutations
We examine the interplay between the three factors—mutation rate, resource availability and maximum population size and ask whether these factors amplify or offset each other’s effects in determining the likelihood of populations evolving specific strategies

Summary

Introduction

Reproducing populations of single cells evolve through mutation, natural selection, and genetic drift. Populations of mitotically dividing cells and unicellular organisms evolve under the complex regulation of their environments This regulation can be exerted through variations in abundance of metabolizable resources available to the population. Elegant experiments using unicellular budding yeast grown in low density sucrosecontaining environments show that multicellularity can evolve under resource-poor conditions with cooperation between incompletely separated cell populations [1]. Extending such observations, resource availability is theorized to have played a key role in determining the evolution of developmental mechanisms with resource-rich environments considered more ideal for the evolutionary stabilization of uniclonal, rather than polyclonal populations [2]. LaBar and Adami [4] show that smaller populations can evolve robustness against genetic drift

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