Gain and loss: energetic cost of plant camouflage in Mantodea

Many praying mantis species exhibit remarkable femoral modification representing a key adaptive morphological camouflage in natural environments. To estimate the evolution of the femoral lobe in Mantodea, we performed the analyses of internal phylogenetic relationships, ancestral state reconstruction and estimate species divergence times using175 mitochondrial genomes spanning 20 families and 93 genera. The findings revealed that the phenotype of the femoral lobe originated during the mid-Cretaceous. Subsequently, this trait was retained and further diversified within the Galinthiadidae, Hymenopodidae and Empusidae, whereas it was lost in the family Mantidae. Additionally, analyses of molecular evolutionary rates revealed that seven mitochondrial protein-coding genes (Nd2, Nd5, Nd6, Atp6, Cox2, Cox1 and Cytb) underwent accelerated evolution in mantis lineages that possessing femoral lobes, which might be attributed to the inability of the rigid femoral lobes to contract, resulting in increased energy requirements for mantis locomotion. Further, transcriptomic analysis of leg tissues in Hymenopus coronatus, a species with enlarged femur demonstrated that energy metabolic capacity increases during ontogeny. Metabolomic comparisons between Tenodera sinensis representing femur-absent taxa and H. coronatus revealed that H. coronatus exhibit enhanced capacities for energy metabolism and conversion. Collectively, these findings indicated a trade-off between plant camouflage and energy metabolism during the evolution of Mantodea.