Why some male frogs have sex on land

New York: When it comes to sex, frogs can do it in water, on land and on leaves, but some male frogs have developed the preference for reproducing on land in order to keep competitors away, new research suggests.

It was earlier assumed that natural selection drove frogs to take the evolutionary step to reproduce on land as a way for parents to avoid aquatic predators who feed on the eggs and tadpoles. The new study, published in the journal American Naturalist, showed that some frogs hide eggs on land to reduce competition from other males who also want to fertilise those eggs.

In the study, researchers analysed data on reproductive modes for two families of frogs - Hylidae, or tree frogs, and Leptodactylidae, including about 900 species that are mostly found in Central and South America.

Frogs are known to have up to 40 reproductive modes, with new ones still being discovered. Some species build hidden chambers on land or females lay eggs in folded leaves or in bromeliads, others lay eggs in water and move them or their tadpoles to land, and others get rid of the tadpole stage entirely.

The study sheds light on evolutionary forces that drive diversity. Also, the results give conservationists insights on habitats and species that may need more protection, Zamudio said.

--IANS