Natural selection. II. Developmental variability and evolutionary rate

TL;DR

This paper explores how developmental variability influences evolutionary dynamics by smoothing fitness landscapes, enabling populations to reach higher peaks more efficiently and survive environmental challenges, thus accelerating evolution.

Contribution

It demonstrates how developmental variability modifies the fitness landscape, facilitating evolutionary progress beyond classical genetic variation models.

Findings

Developmental variability smooths fitness landscapes, aiding in peak ascent.

It enhances initial survival under environmental challenges.

Developmental processes synergize with genetic variation to increase evolutionary rate.

Abstract

In classical evolutionary theory, genetic variation provides the source of heritable phenotypic variation on which natural selection acts. Against this classical view, several theories have emphasized that developmental variability and learning enhance nonheritable phenotypic variation, which in turn can accelerate evolutionary response. In this paper, I show how developmental variability alters evolutionary dynamics by smoothing the landscape that relates genotype to fitness. In a fitness landscape with multiple peaks and valleys, developmental variability can smooth the landscape to provide a directly increasing path of fitness to the highest peak. Developmental variability also allows initial survival of a genotype in response to novel or extreme environmental challenge, providing an opportunity for subsequent adaptation. This initial survival advantage arises from the way in which developmental variability smooths and broadens the fitness landscape. Ultimately, the synergism between developmental processes and genetic variation sets evolutionary rate.