Metabolic Adaption of Flexor Carpi Radialis to Amplexus Behavior in Asiatic Toads (Bufo gargarizans)

Abstract

Amplexus is a type of mating behavior among toads that is essential for successful external fertilization. Most studies have primarily focused on the behavioral diversity of amplexus, and less is known regarding the metabolic changes occurring in amplectant males. The aim of this study was to compare the metabolic profiles of amplectant Asiatic toad (Bufo gargarizans) males in the breeding period (BP group) and the resting males in the non-breeding period (NP group). A metabolomic analysis was conducted on the flexor carpi radialis (FCR), an essential forelimb muscle responsible for clasping during courtship. A total of 66 differential metabolites were identified between the BP and NP groups, including 18 amino acids, 12 carbohydrates, and 8 lipids, and they were classified into 9 categories. Among these differential metabolites, 13 amino acids, 11 carbohydrates, and 7 lipids were significantly upregulated in the BP group compared to the NP group. In addition, a KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis identified 17 significant metabolic pathways, including ABC transporters, aminoacyl-tRNA biosynthesis, arginine biosynthesis, pantothenate and CoA biosynthesis, and fructose and mannose metabolism. These results suggest that amplectant male toads are metabolically more active than those during the non-breeding period, and this metabolic adaptation increases the likelihood of reproductive success.

Sexual Dimorphism in the Limb Bones of Asiatic Toad (Bufo gargarizans) in Relation to Sexual Selection

“…The Asiatic toad is an explosive breeder, and reproduction takes place in December–January or January–February with a breeding period of 25–30 days in Nanchong City, China [ 25 ]. In addition, some information on the morphological anatomy, larval development, habitat selection, diet, mating behavior, age structure, brain size evolution, muscular metabolism, and secondary sexual dimorphism of the B. gargarizans has been reported in recent years [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. This study aims to document the traits of sexual dimorphism in the size and shape of the limb bones of the species and explore implications of observed differences for the evolutionary ecology of the B. gargarizans .…”