Evolvability Is Inevitable: Increasing Evolvability Without the Pressure to Adapt

TL;DR

This paper demonstrates that evolvability can increase over time without adaptive pressure, driven by heritable drift and niche accumulation, as shown through simulated models.

Contribution

It introduces a novel explanation that increasing evolvability arises passively from genotypic drift and niche dynamics, without the need for adaptive pressure.

Findings

Evolvability can increase without selection pressure.

Heritable drift biases phenotypic distributions towards higher evolvability.

Simulated models support the passive increase of evolvability over time.

Abstract

Why evolvability appears to have increased over evolutionary time is an important unresolved biological question. Unlike most candidate explanations, this paper proposes that increasing evolvability can result without any pressure to adapt. The insight is that if evolvability is heritable, then an unbiased drifting process across genotypes can still create a distribution of phenotypes biased towards evolvability, because evolvable organisms diffuse more quickly through the space of possible phenotypes. Furthermore, because phenotypic divergence often correlates with founding niches, niche founders may on average be more evolvable, which through population growth provides a genotypic bias towards evolvability. Interestingly, the combination of these two mechanisms can lead to increasing evolvability without any pressure to out-compete other organisms, as demonstrated through experiments with a series of simulated models. Thus rather than from pressure to adapt, evolvability may inevitably result from any drift through genotypic space combined with evolution's passive tendency to accumulate niches.