Directionality of contact networks suppresses selection pressure in evolutionary dynamics

TL;DR

This paper investigates how the directionality of contact networks influences selection pressure in evolutionary dynamics, finding that directionality generally reduces selection pressure and that certain update rules further diminish it.

Contribution

It provides new insights into how directed networks and specific update rules affect the fixation probability and selection pressure in evolutionary processes.

Findings

Directionality of networks suppresses selection pressure across various update rules.

Death-before-reproduction update rules significantly lower selection pressure.

Directed networks generally reduce the impact of fitness differences on fixation probability.

Abstract

Individuals of different types, may it be genetic, cultural, or else, with different levels of fitness often compete for reproduction and survival. A fitter type generally has higher chances of disseminating their copies to other individuals. The fixation probability of a single mutant type introduced in a population of wild-type individuals quantifies how likely the mutant type spreads. How much the excess fitness of the mutant type increases its fixation probability, namely, the selection pressure, is important in assessing the impact of the introduced mutant. Previous studies mostly based on undirected and unweighted contact networks of individuals showed that the selection pressure depends on the structure of networks and the rule of reproduction. Real networks underlying ecological and social interactions are usually directed or weighted. Here we examine how the selection pressure is modulated by directionality of interactions under several update rules. Our conclusions are twofold. First, directionality discounts the selection pressure for different networks and update rules. Second, given a network, the update rules in which death events precede reproduction events significantly decrease the selection pressure than the other rules.