DNA detective work to match unusual tadpoles to adult frogs

Scientists have been working on the tricky puzzle of which tadpoles become which adult frogs.

Giant horned frog tadpole. © Benjamin Tapley/ZSL

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.

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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.

“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.”

Giant horned frog (Megophrys fansipanensis)

Giant horned frog adult. © Luan Thanh Nguyen
Giant horned frog adult (tadpoles pictured in main image above). © Luan Thanh Nguyen

Mount Fanispan horned frog (M. fansipanensis)

Fansipan horned frog adult. © Benjamin Tapley/ZSL
Fansipan horned frog adult. © Benjamin Tapley/ZSL
Fansipan horned frog tadpole. © Benjamin Tapley/ZSL
Fansipan horned frog tadpole. © Benjamin Tapley/ZSL

Hoang Lien horned frog (M. hoanglienensis)

Hoang Lien horned frog adult. © Benjamin Tapley/ZSL
Hoang Lien horned frog adult. © Benjamin Tapley/ZSL
Hoang Lien horned frog tadpole. © Luan Thanh Nguyen
Hoang Lien horned frog tadpole. © Luan Thanh Nguyen

Jingdong horned frog (M. jingdongensis)

Jingdong horned frog adult. © Benjamin Tapley/ZSL
Jingdong horned frog adult. © Benjamin Tapley/ZSL
Jingdong horned frog tadpole. © Benjamin Tapley/ZSL
Jingdong horned frog tadpole. © Benjamin Tapley/ZSL

Maoson horned frog (M. maosonensis)

Maoson horned frog adult. © Benjamin Tapley/ZSL
Maoson horned frog adult. © Benjamin Tapley/ZSL
Maoson frog adult tadpole. © Luan Thanh Nguyen
Maoson frog adult tadpole. © Luan Thanh Nguyen

Annam horned frog (M. intermedia)

Ananm horned frog adult. © Luan Thanh Nguyen
Ananm horned frog adult. © Luan Thanh Nguyen
Ananm horned frog tadpole. © Luan Thanh Nguyen
Ananm horned frog tadpole. © Luan Thanh Nguyen

Read the full papers in Zootaxa: 


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Main image: Giant horned frog tadpole. © Benjamin Tapley/ZSL