Pangenome and transcriptomics reveal the genomic basis associated with interspecific variation of sexually dimorphic nuptial spines in moustache toads.

Keratin gene expansion predates nuptial spine development and is linked to the evolution of sexually dimorphic traits in Leptobrachium toads.

• Why it matters: Understanding the genetic basis of sexual dimorphism is crucial for insights into species diversification, yet its origins in vertebrates remain largely unclear, especially in amphibians.
• What they did: The study constructed a pangenome from six Leptobrachium species and integrated trans-species transcriptomic analyses, focusing on gene duplication, regulation, and expression patterns related to nuptial spines.
• The result: Findings suggest that keratin gene expansion and regulatory recruitment via Hoxc13 influence nuptial spine development, with igfbp2 showing positive selection in species that lost these spines, illuminating mechanisms of trait evolution.