Symbiosis and horizontal gene transfer promote herbivory in the megadiverse leaf beetles

• DOI: 10.1016/j.cub.2024.12.028
• Publication Date: 2025-01-18T00:45:31Z
• Authors: Roy Kirsch; Yu Okamura; Marleny García-Lo...; Benjamin Weiss; Jean Keller; Heiko Vogel; Kayoko Fukumori; Takema Fukatsu; Alexander S. Kons...; Matteo Montagna; Alexey G. Moseyko; Edward G. Riley; Adam Slipinski; Fredric V. Vencl; Donald M. Windsor; Hassan Salem; Martin Kaltenpoth; Yannick Pauchet
• Keywords: Horizontal Gene Transfer; Lineage (genetic); Convergent evolution

Beetles that feed on the nutritionally depauperate and recalcitrant tissues provided by leaves, stems, roots of living plants comprise one-quarter herbivorous insect species. Among key adaptations for herbivory are plant cell wall-degrading enzymes (PCWDEs) break down fastidious polymers in wall grant access to nutritious content. While largely absent from non-herbivorous ancestors beetles, such PCWDEs were occasionally acquired via horizontal gene transfer (HGT) or uptake digestive symbionts. However, macroevolutionary dynamics their impact evolutionary transitions insects remained poorly understood. Through genomic transcriptomic analyses 74 leaf beetle species 50 symbionts, we show multiple independent events microbe-to-beetle HGT specialized symbioses drove convergent innovations approximately 21,000 13,500 species, respectively. Enzymatic assays indicate these significantly expanded beetles' repertoires thereby contributed adaptation diversification. Our results exemplify how recurring symbiont acquisition catalyzed nutritional success a megadiverse taxon.