The evolution and genomic basis of beetle diversity

Area of Science:

• Evolutionary Biology
• Phylogenomics
• Insect Diversification

Background:

• The evolutionary history of Coleoptera (beetles), the most speciose animal order, and the drivers of their diversification, particularly herbivory, are not fully understood.
• Previous studies lacked comprehensive data to resolve beetle relationships and pinpoint key diversification events.

Purpose of the Study:

• To reconstruct the beetle phylogeny and estimate diversification timing using extensive genomic data.
• To investigate the role of plant feeding and horizontal gene transfer in beetle evolution and adaptive radiation.

Main Methods:

• Phylogenomic analyses using 4,818 genes for 146 species to resolve relationships.
• Diversification timing and rate estimation using 89 genes for 521 species across major lineages.
• Tracing the evolution of genes for symbiont-independent digestion of lignocellulose using 154 genomes/transcriptomes.

Main Results:

• Resolved controversial beetle relationships and dated the origin of Coleoptera to the Carboniferous period.
• Supported codiversification between beetles and angiosperms, highlighting plant-beetle interactions.
• Identified horizontal gene transfer of plant cell wall-degrading enzymes (PCWDEs) coinciding with Mesozoic herbivorous beetle radiations, suggesting a key role in adaptive radiation and the origin of nearly half of extant beetle species.

Conclusions:

• Beetle diversity is shaped by long-term low extinction rates, codiversification with angiosperms, and adaptive radiations.
• Horizontal gene transfer of PCWDEs enabled efficient plant tissue digestion, facilitating specialized herbivory and subsequent diversification.
• The evolution of PCWDEs represents a major evolutionary innovation driving beetle adaptive radiations.