Nearly a century and a half after it was first discovered, a team led by Bengaluru-based herpetologist R Chaitanya has discovered six new species of the Dravidogecko lizard in the Western Ghats. The Dravidogecko species are a small-sized lizard restricted to the wet forests in mid to high elevations.
Dravidogecko annamallensis, the first discovery in this species endemic to the Western Ghats, was discovered in 1875 by British zoologist Albert Gunther in what are now the Annamalai Hills in Tamil Nadu. Up until recently this was believed to be the only species that was populating the Western Ghats.
â€śHowever, we thought how can there be just one species throughout the entire Western Ghats,â€ť begins Chaitanya. â€śThe Ghats are a discontinuous hill range. These geckos have to live in that place; they canâ€™t disperse through a dry zone. Therefore, if these geckos are not dispersing, how can they be the same species? Our hunch was that these barriers in the Western Ghats would have caused some genetic divergence, making them different species.â€ť
In the subsequent fieldwork, the researchers found that the six different species discovered were restricted to different regions of the Western Ghats. â€śThe northern most place they are found is Wayanad. No one knows why there arenâ€™t Dravidogecko species further north from there. And in the south, they go up to Tirunelveli district, which is the end of Western Ghats,â€ť Chaitanya shares.
And so the six new species were discovered, â€śhiding in plain sight,â€ť as Chaitanya puts it.
The six new species have been named Dravidogecko septentrionalis, D. janakiae (in honour of Dr Janaki Ammal, a botanist from Kerala), D. tholpalli, D. meghamalaiensis, D. douglasadamsi (in honour of British author and satirist Douglas Noel Adams) and D. smithi (in honour of British herpetologist Malcolm Arthur Smith).
An interesting history
Another titbit that makes these lizards interesting is that they are ancient â€“ apparently, they came to India 58 million years ago!
â€śAt that time, the landmass that we now call India was not attached to Asia â€“ it was still floating in the tepid sea like an island would. So, these geckos essentially crossed an oceanic barrier to cross into India,â€ť Chaitanya explains.
As if that wasnâ€™t cool enough, hereâ€™s how the researchers believe the unassuming lizards did it â€“ â€śAt different points in our planetâ€™s history, the sea levels have been quite low. The species could just have island-hopped their way to the floating Indian peninsula,â€ť Chaitanya adds.
The nocturnal reptiles are great climbers â€“ so youâ€™ll find them in tree trunks, and also in abandoned buildings. â€śAll these different species inhabit the same ecological niche across their distribution and therefore display very few morphological differences. However, DNA-based molecular analyses can easily tell them apart!â€ť Chaitanya says.
Implications for conservation
The discovery of these six species has thrown the floor wide open for other researchers to explore the Western Ghats, whose status as a biodiversity hotspot has been reinforced with this discovery.
â€śWe believe that there are about 15 species of the Dravidogeckoâ€¦ the discovery of these six has just set the foundation,â€ť Chaitanya says. â€śFurther, if someone wants to work with their ecology, they know which species they are working with.â€ť
The discovery has implications for conservation too. While it was earlier believed that only Dravidogecko annamallensis inhabited the entire Western Ghats, they were believed to be in higher numbers, making it low priority for conservation efforts.
â€śBut now that we know that these are more species limited to certain regions in smaller numbers, it could lead to more efforts to conserve them. The IUCN (International Union for Conservation of Nature) will recognise them and assign a conservation status to them,â€ť Chaitanya says.
IUCN is an international environmental organisation with governmental and non-governmental organisations that â€śprovides public, private and non-governmental organisations with the knowledge and tools that enable human progress, economic development and nature conservation to take place together.â€ť It recognises species as critically endangered, endangered and vulnerable.
The study was carried out by R Chaitanya in collaboration with Dr Varad Giri, Director, Foundation for Biodiversity Conservation, Dr Deepak Veerappan, Natural History Museum, London (NHM), Dr Aniruddha Datta-Roy, National Institute of Science Education and Research (NISER), Bhubaneshwar, Dr BHCK Murthy, Zoological Survey of India, Kozhikode (ZSIK) and Dr Praveen Karanth from the Indian Institute of Science, Bangalore (IISc). The study was recently published in the international taxonomic journal, Zootaxa.