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.