# The Minimum Environmental Perturbation Principle: A New Perspective on Niche Theory

## TL;DR

This paper extends MacArthur's ecological equilibrium optimization principle to a broader class of models, showing that stable states minimize environmental perturbation and providing new insights into eco-evolution and community assembly.

## Contribution

It generalizes the optimization principle to a wider range of systems within niche theory, linking equilibrium states to minimal environmental disturbance.

## Key findings

- Equilibrium states minimize environmental perturbation caused by species.
- The principle applies under specific conditions validated in experiments.
- Provides new predictions for eco-evolution and community assembly.

## Abstract

Fifty years ago, Robert MacArthur showed that stable equilibria optimize quadratic functions of the population sizes in several important ecological models. Here, we generalize this finding to a broader class of systems within the framework of contemporary niche theory, and precisely state the conditions under which an optimization principle (not necessarily quadratic) can be obtained. We show that conducting the optimization in the space of environmental states instead of population sizes leads to a universal and transparent physical interpretation of the objective function. Specifically, the equilibrium state minimizes the perturbation of the environment induced by the presence of the competing species, subject to the constraint that no species has a positive net growth rate. We use this "minimum environmental perturbation principle" to make new predictions for eco-evolution and community assembly, and describe a simple experimental setting where its conditions of validity have been empirically tested.