Quasispecies Theory for Evolution of Modularity

TL;DR

This paper develops a quasispecies theoretical framework to understand how modularity in biological systems evolves over time under environmental pressures, providing analytical tools and predictions validated by simulations.

Contribution

It introduces a novel quasispecies model for the evolution of modularity, deriving relationships between environmental change rates and modularity growth, and predicts steady-state modularity principles.

Findings

Steady-state fitness can be computed in changing environments.

A fluctuation dissipation relation links environmental change and modularity growth.

Predictions are consistent with protein evolution simulations.

Abstract

Biological systems are modular, and this modularity evolves over time and in different environments. A number of observations have been made of increased modularity in biological systems under increased environmental pressure. We here develop a quasispecies theory for the dynamics of modularity in populations of these systems. We show how the steady-state fitness in a randomly changing environment can be computed. We derive a fluctuation dissipation relation for the rate of change of modularity and use it to derive a relationship between rate of environmental changes and rate of growth of modularity. We also find a principle of least action for the evolved modularity at steady state. Finally, we compare our predictions to simulations of protein evolution and find them to be consistent.