# Phylostratigraphic Analysis Reveals the Evolutionary Origins and Potential Role of New Genes in the Adaptive Evolution of Spodoptera frugiperda

## TL;DR

This study explores how new genes have contributed to the rapid adaptation of the fall armyworm, a major agricultural pest, using evolutionary analysis.

## Contribution

The study identifies 277 newly evolved genes in Spodoptera frugiperda and links them to adaptive traits like pesticide resistance and environmental response.

## Key findings

- 277 new genes originated after the divergence of Spodoptera and show signs of recent evolutionary origin.
- These genes are enriched in the antenna and brain, suggesting roles in chemosensory and neural functions.
- New genes act as hubs in regulatory networks under environmental stress, such as pesticide exposure.

## Abstract

The fall armyworm, Spodoptera frugiperda, has become one of the most damaging agricultural pests worldwide, yet the genetic basis of its extraordinary adaptability remains elusive. Recent studies have highlighted the pivotal role of newly evolved genes in adaptive evolution, and phylostratigraphy has emerged as a powerful conceptual framework to trace their origins. Here, we adopt this framework to investigate how new genes have contributed to the rapid adaptive evolution of S. frugiperda. Using high-quality genomic data, we inferred gene ages across evolutionary phylostrata and identified 277 newly evolved genes that originated after the divergence of Spodoptera. These new genes exhibit hallmark genomic signatures of recent origin, including shorter coding regions, simplified structures, and relaxed evolutionary constraints. Interestingly, transcriptomic analyses revealed strong tissue specificity, with pronounced enrichment in the antenna and brain, indicating possible involvement in chemosensory and neural functions essential for environmental and behavioral adaptation. Under diverse environmental challenges such as pesticide and parasitoid wasp exposure, and virus infection, we found many of the new genes acted as hubs in the regulatory networks associated with pesticide response. Together, our findings suggest that the emergence of new genes has played a critical role in shaping the rapid adaptive evolution of S. frugiperda and provide broader insights into how newly evolved genes contribute to species adaptation.