Defensive complexity in antagonistic coevolution

TL;DR

This paper explores how complex information processing can serve as a defensive strategy in coevolution, particularly in host-pathogen interactions, by creating rugged fitness landscapes that slow down adversarial evolution.

Contribution

It introduces a novel model of coevolution where complex information processing acts as a defense mechanism, highlighting its role in shaping evolutionary dynamics.

Findings

Complex processing induces rugged fitness landscapes.

Species can slow adversary evolution through processing complexity.

Potential relevance to vertebrate immune system dynamics.

Abstract

One strategy for winning a coevolutionary struggle is to evolve rapidly. Most of the literature on host-pathogen coevolution focuses on this phenomenon, and looks for consequent evidence of coevolutionary arms races. An alternative strategy, less often considered in the literature, is to deter rapid evolutionary change by the opponent. To study how this can be done, we construct an evolutionary game between a controller that must process information, and an adversary that can tamper with this information processing. In this game, a species can foil its antagonist by processing information in a way that is hard for the antagonist to manipulate. We show that the structure of the information processing system induces a fitness landscape on which the adversary population evolves, and that complex processing logic is required to make that landscape rugged. Drawing on the rich literature concerning rates of evolution on rugged landscapes, we show how a species can slow adaptive evolution in the adversary population. We suggest that this type of defensive complexity on the part of the vertebrate adaptive immune system may be an important element of coevolutionary dynamics between pathogens and their vertebrate hosts.