Convergent evolution of metabolic systems in phytophagous beetles (Coleoptera: Buprestidae and Cerambycidae)

Approximately 25% of known animal species are plant-feeding (phytophagous) insects (~401,000 species), and a large fraction of these are beetles. Most phytophagous beetles belong to the clades Phytophaga (leaf beetles, longhorn beetles, and weevils) and Buprestoidea (metallic wood boring beetles). The plant cell wall, which makes up most of the diet of phytophagous beetles, is difficult to digest and lacks protein and many nutrients needed for successful development. Phytophagous beetles have evolved a remarkable diversity of adaptations to cope with these nutrient deficiencies and their host plants' chemical and structural defenses. Notably, they degrade plant cell walls using symbiont-derived or endogenous plant cell wall degrading enzymes (PCWDEs). Buprestoidea and Phytophaga shared a common ancestor more than 200 million years ago. However, we have shown that their metabolic systems are convergent, and their genomes encode a remarkably similar repertoire of endogenous PCWDEs. Many questions remain about the convergent evolution of metabolic systems in Buprestoidea and Phytophaga. We present new insights into the genomic basis and evolution of specialized plant-feeding and the metabolism of plant tissues in beetles, focusing on exemplars from the clades Phytophaga and Buprestoidea and their genes encoding PCWDEs. Our study further illuminates the convergent evolution of specialized plant feeding in Coleoptera and the evolutionary processes that have shaped the remarkable diversity of phytophagous beetles.