Soundguide designed for frogs

Researcher: Everyone quacks in his own way

Malagasy Sirens Tree Frog © Miguel Vences / Frank Glaw
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Was it really the nightingale and not the lark? For some people, it is almost impossible to assign bird sounds clearly. However, most people would fail completely when it comes to croaking frogs. The frog reveals by his call, to which kind he belongs. Scientists are proving this impressively with a new Soundguide: The calls of around 250 species of Malagasy frogs are recorded on three audio CDs.

This extraordinary collection as well as comprehensive morphological and genetic data of tadpoles are the result of a three-year research project in Madagascar.

The biologists Frank Glaw of the Zoological State Collection Munich, Professor Miguel Vences of the Technical University of Braunschweig and Professor Noromalala Raminosoa of the University of Antananarivo in Madagascar jointly pursued an ambitious goal locally: It was necessary to develop methods that a rapid and reliable determination of frogs and thus also support effective species protection. Amphibians, and especially the frogs, are endangered worldwide in their biodiversity. In Madagascar alone, 55 species of amphibians are threatened with extinction.

Madagascar: 130 million years of isolation

Madagascar has been separated from mainland Africa for 130 million years and India for 90 million years. Therefore, a unique variety of animals and plants developed on this island, which is today increasingly threatened by the rapidly progressing destruction of forest areas. For their preservation, protected areas must now be carefully selected to ensure the survival of as many species as possible. Above all, areas with a unique flora and fauna - so-called endemic centers - must be identified. The indicators are in particular those about 224 known frog species, which occur to 99 percent only in very specific regions of Madagascar.

However, the search and exact location of adult frogs is not that easy: they often live hidden underground or even high in the trees, and many are confusingly similar. Quite different, however, their croaking: Here, the scientists could almost always clearly assign - and did not even need to catch the frog. Bioacoustics has become such an important component of a fast acquisition system. In addition, scientists in Madagascar developed identification aids for tadpoles, and as the latest tool they adapted a genetic method of determination, the so-called DNA barcoding. display

This genetic analysis is always used when the species refuse to have a clear reputation. DNA is first extracted from the tissue of the specimens in question. Scientists sequence and analyze a fragment of mitochondrial THEN. Its length is about 550 base pairs.

Created gene signatures of frog species

From almost all known and many new, still undescribed frog species of Madagascar such gene signatures have since been created. In the future, they will make it possible to quickly and clearly allocate the males. This work, which fits in seamlessly with global efforts to establish a standard of identification for all organisms by means of genome signatures, was presented at the First International Congress for the Barcode of Life in London in February 2005, and in the Professional journal "Philosophical Transactions of the Royal Society" published.

Fascination Kr ten

The expeditions for the project are now over. A standard procedure for the fast detection of amphibians in Madagascar is available and should help to set meaningful priorities in the Malagasy nature conservation. Due to the close cooperation in the course of the VolkswagenStiftung's partnership program, Madagascar now has the know-how and the equipment for further bioacoustical and genetic data collections. For the involved scientists from Germany it will probably not have been the last expedition to this island, because the application of the newly developed methods opens up further fascinating research perspectives.

"When I was four years old, I started gathering crates and salamanders and almost drove my parents crazy, " Vences confesses. The fascination for the crutches has left him just as little as his colleague Frank Glaw. No floods, political riots or the threat of malaria prevented them from conducting field research on Madagascar. By the way, by now they discovered more than a hundred new species of frogs, as well as new types of snakes, lizards and a hitherto unknown dwarf chameleon - one of the smallest reptiles in the world.

The Volkswagen Foundation supported the project "Soundguide für Fr sche" as part of its partnership program with 63, 000 euros.

(idw - Volkswagen Foundation, 19.01.2006 - DLO)