Gene coexpression networks reveal molecular interactions underlying cichlid jaw modularity

Area of Science:

• Evolutionary biology
• Genomics
• Developmental biology

Background:

• Cichlid fish jaws exemplify evolutionary modularity, crucial for their trophic diversification and adaptive radiations.
• Previous research focused on functional, morphological, and genetic aspects of cichlid jaw modularity.
• This study introduces transcriptional modularity by analyzing jaw transcriptomes and gene coexpression networks.

Purpose of the Study:

• To investigate transcriptional decoupling in cichlid oral and pharyngeal jaws.
• To compare gene coexpression networks between oral and pharyngeal jaws.
• To identify gene regulatory networks involved in jaw development and adaptation.

Main Methods:

• Whole transcriptome sequencing of oral and pharyngeal jaws.
• Comparative analysis of gene coexpression networks.
• In silico annotation of gene regulatory networks, including Wnt and AHR signaling pathways.

Main Results:

• Transcriptional decoupling underlies functional decoupling of cichlid jaws, with independent evolution in recently diverged species.
• Gene coexpression networks show high preservation but substantial rewiring, reflecting a common jaw regulatory program.
• Jaw-specific and species-specific modules were identified, along with a regulatory network linking Wnt and AHR pathways to jaw development and environmental response.

Conclusions:

• Transcriptional rewiring of ancestral networks likely drove the modular evolution of cichlid jaws.
• Gene network reuse is significant in the modular evolution of vertebrate jaws.
• The presented networks serve as a resource for future research on jaw morphogenesis and trophic adaptation.