What made niches available for the radiation of: amphibians

Amphibian adaptive radiations are characterized by the relationship between habitat utilization and morphological variation. Biologists emphasized that life history and reproductive modes are integral aspects to adaptive radiation. Few examples of the niches they thrive are located in lands (e. g. wetlands) especially for adult frogs and water body (ponds) where tadpoles live as an example. It's life form is both an aquatic and terrestrial organism, so they must thrive on particular niches for their survival.