Evolutionary trajectories of teleost olfactory signaling genes shaped by long-term redundancy after whole-genome duplication

Whole-genome duplication (WGD) facilitates molecular and species diversification. Here, we investigated olfactory marker protein ( omp ) genes duplicated by the teleost-specific WGD through phylogenetic, syntenic, expression, and promoter analyses. Our results suggest that duplicated omp genes were retained over an extended evolutionary period spanning approximately 300 million years and underwent both non- and sub-functionalization. Comparisons with the host gene capn5 and cross-species reporter assays further support regulation by short upstream regions and suggest sequence-level divergence after WGD. In addition, analyses of multiple olfactory signal transduction genes revealed coordinated long-term retention of duplicated gene pairs across the signaling cascade, consistent with gene dosage constraints and prolonged functional redundancy after WGD. These findings imply that the teleost olfactory system retained ancestral redundancy over exceptionally long evolutionary timescales, thereby facilitating regulatory and functional diversification within the olfactory signaling pathway.