Scientists reveal the truth about a 'true frog'

A male Warszewitsch’s frog in its natural habitat (Credit: Robert Puschendorf)

A common species of true frog found across Central America appears to have been keeping its “multiple identities” a secret all along, new research led by the University of Plymouth suggests.

British and Costa Rican herpetologists used DNA barcoding to study the species currently known as Warszewitsch’s frog, which is found in Honduras, Nicaragua, Costa Rica and Panama.

A true frog (meaning it is assigned to the family Ranidae), authors writing in the open-access journal ZooKeys suggest that the well-known species – known to science since 1857 – may in fact consist of multiple different “cryptic” species.

This phenomenon is well documented among tropical amphibian fauna, where high levels of genetic variation within populations of a single species surpass levels found between different, classified species.

The study was conducted in the Área de Conservación Guanacaste​ (ACG), Costa Rica, by BSc (Hons) Conservation Biology graduate James Cryer, Lecturer in Conservation Biology Dr Robert Puschendorf, and former PhD candidate Dr Felicity Wynne from the ​University of Plymouth, and Dr Stephen Price at ​UCL.

Through DNA barcoding, which compares short snippets of DNA sequences between individuals sampled, the scientists analysed specimens from three different geographic areas within Costa Rica and Panama.

They used sequences derived from mitochondria, the energy producing power houses found in animal cells, and their results indicated there was enough genetic variation to suggest cryptic species are indeed present.

The team chose this particular species because cryptic species were previously identified at two Panamanian sites. Now, the samples from Costa Rica broaden the study area, suggesting that there could be multiple species going by the name Warszewitsch’s frog all across its known distribution.

Conservation biologist and lead author James Cryer says:

“The next step will be to gather more samples throughout the full range of the species. Additionally, if we are to fully discern one species variant from another, further studies that compare the physical, behavioural and ecological characteristics of the frogs, alongside more genetic testing is needed.”

Overall, findings like these are important to help improve understanding of amphibian biodiversity and, thus, work towards its conservation.

Cryer adds:

“If indeed there are multiple species, it may be that they have different ecological requirements, and therefore different approaches to their conservation are needed. This study further reinforces the power of DNA barcoding for rapid, preliminary species identification. Especially in the tropics, where habitat loss, climate change and infectious disease continually threaten many undescribed amphibian species.”

<p>An amplecting pair of Warszewitsch’s frogs in El Valle de Antón, Panama<br></p>
An amplecting pair of Warszewitsch’s frogs in El Valle de Antón, Panama

An amplecting pair of Warszewitsch’s frogs in

Área de Conservación Guanacaste, Costa Rica<br></p>
An amplecting pair of Warszewitsch’s frogs in Área de Conservación Guanacaste, Costa Rica

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