Genomic Insights Into Carnivorous Fish in the Characiformes.

Area of Science:

• Evolutionary biology
• Genomics
• Molecular adaptation

Background:

• Characiformes display significant dietary diversity, particularly carnivorous species adapted to high-protein and high-fat diets.
• The molecular underpinnings of these carnivorous adaptations are not well understood.

Purpose of the Study:

• To investigate the molecular mechanisms driving carnivorous specialization in Characiformes using comparative genomics.
• To identify genes and pathways associated with the adaptation to high-protein and high-fat diets.

Main Methods:

• Comparative genomic analysis of 12 Characiformes genomes, including re-annotation of five species.
• Phylogenetic reconstruction, gene family expansion/contraction analysis, and identification of candidate genes.
• Amino acid site substitution analysis and protein 3D structure modeling for candidate genes.

Main Results:

• Expanded gene families and positively selected genes in Characiformes are linked to amino acid metabolism, lipid absorption/transport, and energy regulation.
• Rapidly evolving genes associated with chitin metabolism were also identified.
• Amino acid substitutions in candidate genes like *phospho1* and *hsd17b7* potentially alter protein structure and function in lipid metabolism.

Conclusions:

• Genomic insights reveal the molecular basis for carnivorous adaptation in Characiformes.
• Candidate genes identified may facilitate efficient high-protein and high-fat diet utilization while mitigating negative effects.
• Findings provide a foundation for future functional studies on dietary adaptation in teleost fish.