The relationship between brain size and digestive tract length do not support expensive-tissue hypothesis in Hylarana guentheri

The brain is among the most energetically costly organs in the vertebrate body. The expensive-tissue hypothesis (ETH) predicts that increasing the size of another costly organ, such as the gut, should compensate for the cost of a small brain. To date, this hypothesis has mainly been tested in homoeothermic animals and in some ectothermic animals (e.g., fishes and anurans). Here, we undertake a test of the ETH by analyzing the relationship between brain size variation and length of the digestive tract in Hylarana guentheri. After controlling for geographical situation and body size, we did not find a correlation between brain mass and the length of the digestive tract in H. guentheri. Our findings suggest that the variation of brain size did not follow general patterns in this species and that the effect of diet quality cannot play a role in the variation of brain