The number of species of bent toed geckos in the Himalayas has gone up from five to about seventeen, a new study has revealed. The geckos, belonging to the genus Cyrtodactylus, are distant relatives of the common house gecko that adorns our walls.
There are 175 described species of Cyrtodactylus geckos in the world, distributed from the Western Himalayas, through Southeast Asia to the Western Pacific, write the authors in the paper. Before this paper, about 17 species were known from Burma, 3 from Nepal, 2 from Pakistan, and rather surprisingly, just 5 from India. The researchers set out to sample geckos from this genus from across the Himalayas, northeast India and the Andaman and Nicobar Islands, over three years.
The researchers carried out analysis of their DNA. Using similarities and differences between genetic sequences, they arrived at a “phylogeny”, which is like a family tree describing the relationship between species.
The analysis has yielded about 17 new species that are genetically distinct from each other, showing that gecko diversity from the Himalayas has been underestimated till now. Some of these are yet to be described formally as new species.
Events from the Indian subcontinent’s evolutionary history have been instrumental in shaping the flora and fauna we find today. The Indian subcontinent is part of the Indian tectonic plate, which started colliding with the Asian tectonic plate about 50 million years ago, giving rise to the Himalayas.
The rise of the Himalayas had a profound effect on the flora and fauna of the Indian subcontinent, and the Cyrtodactylus geckos were no exception. They diverged from their closest relatives, the house geckos and the naked toed geckos, at around this time.
The Himalayas are a complex mountain system, with elevation, rainfall and temperature gradients creating a mosaic of habitats suitable for a large number of species. Over many hundreds of years, ancestral species have given rise to numerous daughter species in the process of “diversification” – the diversity of bent toed geckos is an example of this process.
These species are always found in close association with rocky areas. The authors believe that alluvial plains and lack of suitable rocky habitat prevent the bent toed geckos from dispersing southwards into the peninsula. The Garo-Rajmahal Gap seems to have prevented them from entering the Indian peninsula from northeastern India, while the Indo-Gangetic flood plains prevented their dispersal from the Himalayas.
Praveen Karanth is an Associate Professor at the Centre for Ecological Sciences, Indian Institute of Science. Ishan Agarwal was his PhD student. Website: http://praveenkaranth.weebly.com/; Contact: firstname.lastname@example.org. Journal: Molecular Phylogenetics and Evolution
[Collaborators Aaron Bauer and Todd Jackman are from Villanova University in the US.]