Sunday, April 26, 2015

[Herpetology • 2015] A Phylogeny of the Only Ground-dwelling Radiation of Cyrtodactylus (Squamata, Gekkonidae): Diversification of Geckoella across peninsular India and Sri Lanka

Fig. 1. Maximum likelihood phylogeny (ND2, RAG1, PDC) of Geckoella, with representative photographs of Geckoella species and a map of peninsular India and Sri Lanka showing sample localities (referenced in Table 1). Outgroups not shown (see Fig. S1 for complete tree); node support indicated by circles, solid fill = high support (ML bootstrap P75, Bayesian PP P 0.95), light fill = support only from Bayesian analyses (Bayesian PP P 0.95, ML bootstrap <75). Sample localities (number) follow the taxa labels.
Photographs of each species complex are approximately scaled by their maximum snout-vent length (Smith, 1935; Bauer and Giri, 2004; Somaweera and Somaweera, 2009). Colored branches and locality labels on the map indicate dry zone and wet zone clade membership. | DOI: 10.1016/j.ympev.2014.09.016

The subgenus Geckoella, the only ground-dwelling radiation within Cyrtodactylus, closely overlaps in distribution with brookii group Hemidactylus in peninsular India and Sri Lanka. Both groups have Oligocene origins, the latter with over thrice as many described species. The striking difference in species richness led us to believe that Geckoella diversity is underestimated, and we sampled for Geckoella across peninsular India. A multi-locus phylogeny reveals Geckoella diversity is hugely underestimated, with at least seven undescribed species, doubling previously known richness. Strikingly, the new species correspond to cryptic lineages within described Indian species (complexes); a number of these endemic lineages from the hills of peninsular India outside the Western Ghats, highlighting the undocumented diversity of the Indian dry zone. The Geckoella phylogeny demonstrates deep splits between the Indian species and Sri Lankan G. triedrus, and between Indian dry and wet zone clades, dating back to the late Oligocene. Geckoella and brookii group Hemidactylus show contrasting diversification patterns. Geckoella shows signals of niche conservatism and appears to have retained its ancestral forest habitat. The late Miocene burst in speciation in Geckoella may be linked to the expansion of rain forests during the mid-Miocene climatic optimum and subsequent fragmentation with increasing late Miocene aridification.

Keywords: Mid-Miocene climatic optimum; Aridification; Cryptic species; Historical biogeography

• Species diversity vastly underestimated – 7 potentially new Geckoella from hills of peninsular India.
• Geckoella and brookii group Hemidactylus show contrasting historical diversification in peninsular India and Sri Lanka.
• Signals of niche conservatism in Geckoella, retention of terrestrial habit and forest habitat.
• Late Miocene diversification may be linked to mid-Miocene forest expansion and late Miocene aridification.

Ishan Agarwal and K. Praveen Karanth. 2015. A Phylogeny of the Only Ground-dwelling Radiation of Cyrtodactylus (Squamata, Gekkonidae): Diversification of Geckoella across peninsular India and Sri Lanka. Molecular Phylogenetics and Evolution. 82(A); 193–199. DOI: 10.1016/j.ympev.2014.09.016