Variation in the function of gut microbiota with food levels; the gut metagenomes were compared between tadpoles from the L and H groups; (A) relative abundance of CAzymes at the class level; the values show the mean ± SE; ^*adjusted P < .05; ^**adjusted P < .01; differences in the relative abundance of microbial glycolytic (B) and propionate- and butyrate-fermenting genes (C) between the L and H groups; AA, redox enzymes that act in conjunction with CAZymes; CBM, adhesion to carbohydrates; CE, hydrolysis of carbohydrate esters; GH, hydrolysis and/or rearrangement of glycosidic bonds; GT, formation of glycosidic bonds; PL, nonhydrolytic cleavage of glycosidic bonds.