 Several hundred frog species in adaptive radiations ( e.g. , Eleutherodactylus , the Pacific Platymantis , the Australo @-@ Papuan microhylids , and many other tropical frogs ) , however , do not need any water for breeding in the wild . They reproduce via direct development , an ecological and evolutionary adaptation that has allowed them to be completely independent from free @-@ standing water . Almost all of these frogs live in wet tropical rainforests and their eggs hatch directly into miniature versions of the adult , passing through the tadpole stage within the egg . Reproductive success of many amphibians is dependent not only on the quantity of rainfall , but the seasonal timing . 
