Expansion and Temporal Expression Regulation of Cuticle‐Associated Gene Families: Molecular Basis of Adaptive Evolution of Moulting in Decapods

Moulting is fundamental to decapod growth and development, yet its molecular regulatory mechanisms and relationship with environmental adaptive evolution remain incompletely elucidated. Through comparative genomic and transcriptomic analyses, we identified six cuticle-associated gene families (CP8, CP AMP1A, pro-resilin, CP AM1199, CP575, and CP1246) that underwent significant expansion in decapods, displaying species-specific distribution patterns. Notably, the CP1246 family, specifically expanded in crabs and enriched with calcification-related cuticle domains, likely represents a key evolutionary innovation enabling adaptation to the physical impacts and predation pressures of intertidal environments. Transcriptomic analysis revealed that these expanded gene families exhibit highly specific spatiotemporal expression patterns during the moulting cycle: CP8, pro-resilin, and CP AMP1A show elevated expression during intermolt (InM3), contributing to endocuticle formation, while CP1246, CP575, and CP AM1199 maintain higher expression during other periods, potentially associated with the construction of different exoskeletal regions. Additionally, we identified the ecdysis triggering hormone (ETH) and its receptor (ETHR), confirming their gradually increasing expression pattern during moulting, and through co-expression network analysis, demonstrated that ETH likely coordinates the regulation of genes related to muscle development, immune response, and energy metabolism, collectively supporting the orderly progression of the moulting process. These findings establish an integrated model of decapod moulting regulation, elucidating how cuticle-associated gene family expansion and stage-specific expression promote adaptation to complex ecological environments in decapods, particularly crabs, providing new insights into the molecular foundations of adaptive evolution in crustaceans.