Modularity, criticality, and evolvability of a developmental gene regulatory network

Area of Science:

• Developmental Biology
• Systems Biology
• Evolutionary Biology

Background:

• Phenotypic traits arise from complex regulatory processes, often modeled as networks.
• Functional modularity in these networks allows for independent evolution of subcircuits.
• Traditional methods link function to structural modularity, but this correlation is often weak.

Purpose of the Study:

• To investigate functional modularity in regulatory networks, specifically the dipteran insect gap gene system.
• To determine if dynamical modules exist independently of structural modularity.
• To explain the differential evolvability of expression features within the system.

Main Methods:

• Partitioning the gap gene regulatory network using a novel approach.
• Analyzing the network's dynamical behavior and component sensitivities.
• Assessing the criticality of different subcircuits.

Main Results:

• The gap gene system, despite lacking structural modularity, is composed of dynamical modules.
• These dynamical modules drive distinct aspects of the network's behavior.
• Subcircuits exhibit varying degrees of criticality, correlating with their evolvability.

Conclusions:

• Functional modularity can exist in regulatory networks without apparent structural modularity.
• Dynamical modules provide a framework for understanding independent evolution of biological traits.
• Network criticality influences the evolvability of specific gene expression patterns.