Adult frogs are vulnerable to dehydration because of their highly permeable skins  Unlike large adult frogs, small adult frogs have such a low ratio of body weight to skin surface area that they cannot survive in arid climates
The animals' moisture requirements constitute the most important factor determining where frogs can live in the Yucatan peninsula, which has an arid climate in the north and a wet climate in the south
Small adult frogs in the south have less permeable skins than small adult frogs in the north.