A Linear Reciprocal Relationship Between Robustness and Plasticity in Homeostatic Biological Networks

TL;DR

This paper uncovers a linear reciprocal relationship between robustness and plasticity in evolved gene regulatory networks, revealing an underlying physical principle that constrains biological evolution.

Contribution

It demonstrates a universal reciprocal relationship between robustness and plasticity in homeostatic networks, grounded in a lever principle, and shows this constraint persists through evolution.

Findings

Negative proportionality between target and remnant gene expression changes

Reciprocity follows a lever principle in evolved networks

Evolutionary constraint imposed by this reciprocal relationship

Abstract

In physics of living systems, a search for relationships of a few macroscopic variables that emerge from many microscopic elements is a central issue. We evolved gene regulatory networks so that the expression of target genes (partial system) is insensitive to environmental changes. Then, we found the expression levels of the remaining genes autonomously increase as a plastic response. Negative proportionality was observed between the average changes in target and remnant genes, reflecting reciprocity between the macroscopic robustness of homeostatic genes and plasticity of regulator genes. This reciprocity follows the lever principle, which was satisfied throughout the evolutionary course, imposing an evolutionary constraint.