THESIS COLLOQUIUM
                       Centre For Ecological Sciences
                        Indian Institute of Science
-------------------------------------------------------------------------

  Title   : Biogeography and Systematics of bent-toed geckos (Squamata: Gekkonidae)

  Speaker : Ishan Agarwal

  Date    : 6th February 2014 (Thursday)

  Time    : 11 AM

  Venue   : CES Seminar Hall

High tea will be served before the talk at 10.30 AM
-------------------------------------------------------------------------
Abstract:

The unique geological history of the Indian Plate and its current position at the junction of biogeographic realms make it a fascinating landscape for biogeographers. Geckos are a useful model system for studies in historical biogeography because of their diversity and antiquity. The bent-toed geckos in India include the Palaearctic naked-toed geckos ('Cyrtopodion'), Cyrtodactylus and Geckoella. Each of these have unique distributions, the arid-adapted Palaearctic naked-toed geckos are at the southeastern limit of their global distribution, Cyrtodactylus at the northwestern limit, and Geckoella is endemic to Peninsular India and Sri Lanka. I sampled for bent-toed geckos across India and placed each group in a dated global phylogeny to understand how each group diversified, gaining insights into the biological history of the Indian subcontinent from gecko biogeography. The first chapter deals with the Palaearctic naked-toed geckos and Hemidactylus. Palaearctic naked-toed geckos track the aridification of NW Peninsular India, with middle Miocene dispersal into India and late Miocene diversification while data from Hemidactylus suggests Peninsular India had also begun drying by the early Miocene.

 

The second chapter deals with Cyrtodactylus, the most speciose lizard genus in the Himalayan region. Cyrtodactylus diversification in the Himalayas and Indo-Burma closely tracks geological events related to India-Asia collision, with a number of geographically concordant subclades resolved in Indo-Burma. The third and final paper presents a Geckoella phylogeny and contrasts historical diversification in Geckoella and Peninsular Indian Hemidactylus, which overlap in geographic range and both date to the Oligocene. Geckoella phylogeny reveals deep splits between India and Sri Lanka, and between Indian dry and wet zone species going back to the late Oligocene. Peninsular Indian Hemidactylus and Geckoella show contrasting diversification through time. Geckoella shows signals of niche conservatism and appears to have retained its ancestral forest habitat, and a slowdown in diversification followed by a late Miocene burst in speciation may be linked to historical forest contraction and expansion with global climatic fluctuations. Indian gekkonid diversity is vastly underestimated with sampling revealing 30 potential new species. The Indian dry zone is an overlooked reservoir of biodiversity and field sampling is vital to document basic diversity and distribution. Distinct geographic associations and high diversity make geckos in India an excellent system for historical biogeography.

All are cordially invited.