Adaptive walks in a gene network model of morphogenesis: insights into the Cambrian explosion

TL;DR

This study models gene network-based morphogenesis and adaptive evolution to explain the rapid diversification of body plans during the Cambrian explosion, highlighting how genetic complexity can generate diverse stable patterns.

Contribution

It introduces a simple gene network model demonstrating how combinatorial genetic interactions can produce diverse stable patterns relevant to early animal development.

Findings

Genetic complexity enables diverse stable spatial patterns.

Gene regulation and cell signaling are key to pattern diversity.

Model provides insights into rapid evolutionary transitions.

Abstract

The emergence of complex patterns of organization close to the Cambrian boundary is known to have happened over a (geologically) short period of time. It involved the rapid diversification of body plans and stands as one of the major transitions in evolution. How it took place is a controversial issue. Here we explore this problem by considering a simple model of pattern formation in multicellular organisms. By modeling gene network-based morphogenesis and its evolution through adaptive walks, we explore the question of how combinatorial explosions might have been actually involved in the Cambrian event. Here we show that a small amount of genetic complexity including both gene regulation and cell-cell signaling allows one to generate an extraordinary repertoire of stable spatial patterns of gene expression compatible with observed anteroposterior patterns in early development of metazoans. The consequences for the understanding of the tempo and mode of the Cambrian event are outlined.