Network Evolution of Body Plans

TL;DR

This study uses numerical evolution of gene regulatory networks to uncover how different network motifs like FFLs and FBLs determine stripe formation in arthropod embryogenesis, explaining body plan diversity.

Contribution

It reveals the network topologies underlying stripe formation in arthropods and predicts architectures for less-studied species, advancing understanding of developmental evolution.

Findings

Long germ-band development involves Feed-Forward Loops (FFLs).

Short germ-band development involves negative Feed-Back Loops (FBLs).

Evolved networks match experimental data from Drosophila and Tribolium.

Abstract

Segmentation in arthropod embryogenesis represents a well-known example of body plan diversity. Striped patterns of gene expression that lead to the future body segments appear simultaneously or sequentially in long and short germ-band development, respectively. Regulatory genes relevant for stripe formation are evolutionarily conserved among arthropods, therefore the differences in the observed traits are thought to have originated from how the genes are wired. To reveal the basic differences in the network structure, we have numerically evolved hundreds of gene regulatory networks that produce striped patterns of gene expression. By analyzing the topologies of the generated networks, we show that the characteristics of stripe formation in long and short germ-band development are determined by Feed-Forward Loops (FFLs) and negative Feed-Back Loops (FBLs) respectively. Network architectures, gene expression patterns and knockout responses exhibited by the artificially evolved networks agree with those reported in the fly Drosophila melanogaster and the beetle Tribolium castaneum. For other arthropod species, principal network architectures that remain largely unknown are predicted.