DNA detective work to match unusual tadpoles to adult frogs

In the UK, it is quite easy to work out which frog and toad tadpoles turn into which adults, as there are only four native species. In Vietnam however, there are more than 270 species.

Scientists from Zoological Society of London (ZSL), Indo-Myanmar Conservation, The Australian Museum and Hoang Lien National Park have been analysing the DNA of the tadpoles and adults of six species of Asian horned frogs found in Vietnam's mountain forests.

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“Frogs and their tadpoles look nothing like each other but it’s important to know which tadpole becomes which frog.” says lead author Benjamin Tapley, ZSL’s curator of reptiles and amphibians.

“It helps us detect the presence of a species, especially as adult frogs can be seasonally active and difficult to find, and allows us to identify which places might be important frog breeding sites that need protection.”

As well as DNA samples, the researchers collected geographical data, morphological measurements and took photos of the tadpoles.

The team were able to identify and describe the tadpoles of six Asian horned frogs.

“During my time searching for frogs along streams, I have often been impressed by the unusual behaviours of some tadpoles feeding at the water surface,” says Luan Nguyen, co-author and scientific officer of the ATP/IMC.

“This has driven me to find answers for questions: "What species are they?" and "How and why do they choose to feed in such a way?" The description of the morphological characteristics of these tadpoles is helping to answer these questions and has moved us one step closer to understanding their evolution and natural history.”