Thursday, August 14, 2014

[Herpetology • 2014] Insights into Himalayan Biogeography from Geckos: A Molecular Phylogeny of Cyrtodactylus (Squamata: Gekkonidae)



Fig. 1. Map of the circum-Himalayan region showing sampling locations of Himalayan and Indo-Burmese Cyrtodactylus.
Numbered localities are referenced in Table 1; multiple samples of a species are numbered serially; colors correspond to clades marked in Fig. 2: Blue = Clade F, brown = Clade E, cyan = Clade A, green = Clade B, orange = Clade N, pink = Clade L, purple = Clade G, red = Clade H, yellow = Clade M. Major rivers are marked by a bold line and capitalized text, areas used in ancestral area reconstruction delineated by dotted lines and river courses, labelled with underlined text (refer to methods for definitions). The Indo-Gangetic Flood Plains (dotted arrows indicate the extent) lie south of the Himalayas and the Garo-Rajmahal Gap separates the Shillong Plateau and Rajmahal Hills. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)


Highlights
• Species diversity vastly underestimated – 16 potentially new Cyrtodactylus from the Himalayas and NE India.
• Diversification within Cyrtodactylus tracks the India–Asia collision and subsequent geological events.
• A number of geographically concordant clades are resolved within Indo-Burmese Cyrtodactylus.

ABSTRACT  
The India–Asia collision profoundly influenced the climate, topography and biodiversity of Asia, causing the formation of the biodiverse Himalayas. The species-rich gekkonid genus Cyrtodactylus is an ideal clade for exploring the biological impacts of the India–Asia collision, as previous phylogenetic hypotheses suggest basal divergences occurred within the Himalayas and Indo-Burma during the Eocene. To this end, we sampled for Cyrtodactylus across Indian areas of the Himalayas and Indo-Burma Hotspots and used three genes to reconstruct relationships and estimate divergence times. Basal divergences in Cyrtodactylus, Hemidactylus and the Palaearctic naked-toed geckos were simultaneous with or just preceded the start of the India–Asia collision. Diversification within Cyrtodactylus tracks the India–Asia collision and subsequent geological events. A number of geographically concordant clades are resolved within Indo-Burmese Cyrtodactylus. Our study reveals 17 divergent lineages that may represent undescribed species, underscoring the previously undocumented diversity of the region. The importance of rocky habitats for Cyrtodactylus indicates the Indo-Gangetic flood plains and the Garo-Rajmahal Gap are likely to have been important historical barriers for this group.

Fig. 3. Bayesian timetree of Cyrtodactylus showing ML ancestral range reconstructions with probabilities from BBM analysis shown diagonally below and to the left of key nodes (pie charts). Blue bars at nodes represent 95% HPD, branches are colored by distributional area (areas shown in Fig. 1, details in methods). Timing of major geological events indicated in top row, distributions of Cyrtodactylus clades relative to major rivers indicated on branches.


 Ishan Agarwal, Aaron M Bauer, Todd R Jackman and K Praveen Karanth. 2014. Insights into Himalayan Biogeography from Geckos: A Molecular Phylogeny of Cyrtodactylus (Squamata: Gekkonidae). Molecular Phylogenetics and Evolution.  DOI: dx.doi.org/10.1016/j.ympev.2014.07.018

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