Abstract: Transitions between nocturnal and diurnal niches alter sensory and physiological demands, yet whether shifts toward daytime activity are accompanied by recurrent genomic changes across independent lineages remains unclear. Sataspes xylocoparis is an unusual diurnal, nectar-feeding member of the predominantly nocturnal hawkmoth subfamily Smerinthinae and exhibits striking carpenter-bee mimicry. We generated the first chromosome-level genome of this species and analyzed it within a standardized 29-species lepidopteran framework, including 17 sphingids spanning different diel niches. The 429.11-megabase assembly comprised 29 pseudochromosomes and recovered 98.8% of expected lepidopteran orthologs. Phylogenomic analyses recovered Sataspes xylocoparis within Smerinthinae as sister to Clanis bilineata, while extensive macrosynteny with Manduca sexta indicated that its ecological specialization occurred against a largely conserved chromosomal background. Gene-family analyses revealed lineage-associated remodeling of gene families associated with chemosensation, xenobiotic metabolism, and lipid biosynthesis, while episodic positive selection affected genes involved in metabolism, membrane trafficking, and regulatory processes. Comparisons among focal hawkmoth lineages with daytime activity identified only five shared same-direction gene-family shifts, none of which was exclusive to these lineages. Together, these results suggest that shifts toward daytime activity can involve different combinations of lineage-associated and recurrent genomic changes superimposed on a conserved chromosomal architecture. The chromosome-level genome and prioritized candidate families and loci provide a comparative foundation for future studies of diel-niche evolution, adult feeding ecology, and carpenter-bee mimicry in Sphingidae.

Key words: comparative genomics, diel-niche transition, gene-family evolution, Phylogenomics, Sphingidae, Batesian mimicry