Why 2014 is the year of the frog
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It’s raining frogs in India. The year 2014 has been an extraordinary year in the discovery (and re-discovery) of frogs.
The last decade has witnessed a number of new discoveries in frog species, but finding 41 species new to science in a single year—and from the same region of India—is a phenomenal occurrence, especially when rapid economic development has shrunk pristine ecosystems. Further, most of these discoveries have taken place outside protected areas such as national parks and wildlife sanctuaries.
The latest on the list are nine new species of bush frogs from the Western Ghats region that have been described in a research paper by S.P. Vijayakumar, Kartik Shanker, K.P. Dinesh and Mrugank Prabhu, to be published on Wednesday in Zootaxa, a journal for zoological taxonomists.
They are in addition to discoveries this year of six new species of golden-backed frogs, 14 new species of dancing frogs and 12 species of night frogs led by S.D. Biju, head of Systematics Lab at Delhi University.
All these discoveries have been made in the rainforests of the Western Ghats, one of eight “hottest hotspots for biodiversity” in the planet. Home to the highest number of endemic species in India, the Western Ghats has also been in the news as its fragile ecology faces destruction from unregulated mining, pollution and habitat loss owing to human settlements and construction.
“Bush frogs are miniature frogs, some so small that they can be placed on your thumbnail,” says Kartik Shanker, co-author and associate professor, Centre for Ecological Sciences, Indian Institute of Science.
Bush frogs of the genus Raorchestes are found mainly in the Western Ghats. Raorchestes are nocturnal, tiny frogs around 15–45mm in length. They are so tiny and delicate that only a trained eye can spot them in the open.
A few years ago, this writer went looking for frogs in the rainforest with a research team in the dead of night. The forest came alive with a chorus of frog calls as flash lights, like so many light-sabres, danced in a frenzied mission for a glimpse of these lesser denizens of the forest.
Finally, the search party stumbled upon a bush frog by tracking its call. The team was amazed by the powerful croaking call of this tiny little being.
The spectacularly coloured Raorchestes and Rhacophorus belong to the ‘Rhacophoridae’ family and are called tree frogs. While Rhacophorus are mostly arboreal—living in trees—Raorchestes can be found in canopy, sub-canopy, shrubs and even forest floor and grasslands; hence the name bush frogs for this sub-group. There are about 40 species of Raorchestes and many of them are critically endangered.
The team led by Vijayakumar and Shanker collected species samples from various places in the Western Ghats. They used a combination of molecular genetic data, geographic range, morphology and acoustics to separate the frogs into lineages—descendants of a common ancestor that lived a million or more years ago. The team came out with more than 20 potentially new lineages, which have separated from each other to different degrees, and nine new species that were different according to genetics, morphology, acoustics and geography.
The fact that so many new lineages were discovered across various places in the Western Ghats—such as Agasthyamalai in Kerala, Anaimalai and Nilgiris in Kerala and Tamil Nadu, and Kudremukh in Karnataka—shows how little these frogs have been studied. “Historically, all the frogs have not been sampled and studied. The discovery of new species for groups such as frogs in a poorly studied region is hardly surprising,” says Shanker.
Scientists are in a race against time. They think more species could be found but fear many could be lost even before they are described.
Frogs are important indicators of the state of our environment but the slightest climatic change can harm them. “What is really exciting for us is taking this forward to understand the ecological, evolutionary and biogeographic processes of diversification that have led to this spectacular diversity and endemism and working out strategies for conservation,” says Vijayakumar.
In the world of frog research, says the team, 2015 may even be an even more spectacular year.