David Element's Wildlife Web Page Amphibians and Reptiles 24

David Element

Wildlife Photography

and Digital Video Images

____ Amphibians and Reptiles 24 - Pool Frogs 1

POOL FROG Rana lessonae

The 'Green' Frog complex consists of two true species, the Pool Frog, the Marsh Frog Rana ridibunda and a hybrid between the two, the Edible Frog Rana esculenta, the population of which can only be sustained by cross-breeding of this hybrid with one of the original 'parent' species. (Source data: 'Amphibians and Reptiles of Surrey', Wycherley and Anstis). It is difficult to comprehend how such an arrangement of apparent gene recycling can confer any biological advantage, but presumably there must be a purpose otherwise it is difficult to imagine why this situation has arisen in the first place. Ideally the hind leg length should be measured in order to distinguish between these frogs. However, anyone who has tried to approach a 'green' frog will be only too well aware of the difficulty in doing this as they are remarkably well camouflaged and the usual first sign of their presence is a telltale plop into the nearest water - before they have actually been seen by the would-be spotter. The first individual was photographed in the Dordogne where these frogs are clearly very common. It very closely matches the reference photograph on the colour plate in Amphibians and Reptiles of Surrey' - and for the record it was the only frog which didn't jump before the photographer had a chance to point his camera! The remaining two (digital) photographs were taken in Brittany, where for some reason at least some of the frogs appear to be more approachable. The younger of these frogs was a particularly nicely marked individual and both have a pale green dorsal stripe, a feature which may help to distinguish Pool and Edible Frogs from Marsh Frogs, but unfortunately not from one another. It is suggested that the texts of 'Amphibians and Reptiles - A Natural History of the British Herpetofauna' should be consulted for further information about these rather bizarre genetics. With thanks to Julia Wycherley for her valuable second opinion about the identity of the Brittany frogs.

RECOMMENDED REFERENCES:

'AMPHIBIANS AND REPTILES OF SURREY', JULIA WYCHERLEY AND RICHARD ANSTIS, SURREY WILDLIFE TRUST 2001, ISBN 0 9526065 6 9 - see: http://www.surreywildlifetrust.co.uk/ for further information about the Surrey Wildlife Atlas series.

'AMPHIBIANS AND REPTILES - A NATURAL HISTORY OF THE BRITISH HERPETOFAUNA', TREVOR BEEBEE AND RICHARD GRIFFITHS, THE NEW NATURALIST SERIES, HARPERCOLLINS, 2000, ISBN 0 0022008 4 8

Links to 'ARKive' species accounts: