Conserved genomic loci with contrasting transposable element landscapes reveal divergent evolution of tandem P450 clusters in noctuid moths

Locus 1 showed significantly higher TE enrichment in noctuids and diverse TE compositions, whereas Locus 2 contained extensive P450 arrays despite relatively lower TE abundance. However, TE enrichment was not strongly associated with P450 copy number variation, suggesting that TE accumulation represents a locus-specific genomic feature rather than a universal driver of P450 expansion. Evolutionary analyses detected episodic diversifying selection in both loci, indicating heterogeneous selective pressures following gene duplication.

Transcriptomic analysis of Spodoptera frugiperda under insecticide stress further revealed contrasting regulatory patterns: Locus 2 paralogs exhibited coordinated expression responses, whereas Locus 1 paralogs displayed greater expression variation. Together, our findings demonstrate that conserved genomic hotspots with distinct structural and regulatory properties have contributed to the repeated expansion and diversification of P450 clusters in noctuid moths.