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Repeated evolution of terrestrial lineages in a continental lizard radiation


Lajmi, Aparna; Verma, Anjali; Karanth, Praveen (2019), Repeated evolution of terrestrial lineages in a continental lizard radiation, Dryad, Dataset,


The ‘early-burst’ model of adaptive radiation predicts an early increase in phenotypic disparity concurrent with lineage diversification. Although most studies report a lack of this coupled pattern, the underlying processes are not identified. The continental radiation of <i>Hemidactylus</i> geckos from Peninsular India includes morphologically diverse species that occupy various microhabitats. This radiation began diversifying ~36 Mya with an early increase in lineage diversification. Here, we test the ‘early-burst’ hypothesis by investigating the presence of ecomorphs and examining the pattern of morphological diversification in a phylogenetic framework. Two ecomorphs— terrestrial and scansorial species— that vary significantly in body size and toepad size were identified. Unlike the prediction of the ‘early-burst’ model, we find that disparity in toepad morphology accumulated more recently ~14 Mya and fit the OU model. Ancestral state reconstruction of the two ecomorphs demonstrates that terrestrial lineages evolved independently at least five times from scansorial ancestors, with the earliest diversification in terrestrial lineages 19–12 Mya. Our study demonstrates a delayed increase in morphological disparity as a result of the evolution of terrestrial ecomorphs. The diversification of terrestrial lineages is concurrent with the establishment of open habitat and grasslands in Peninsular India, suggesting that the appearance of this novel resource led to the adaptive diversification.

Usage Notes

This dataset includes 42 morphological measurements from preserved specimens. Data on 33 specimens were included from published literature (Agarwal, Giri, & Bauer, 2011; Gaikwad, Kulkarni, Bhambure, & Giri, 2009; Giri, 2008; Giri & Bauer, 2006; Giri & Bauer, 2008; Mirza & Sanap, 2014; Murthy, Bauer, Lajmi, Agarwal, & Giri, 2014). The following traits were measured to capture the differences in size, body shape, head shape and shape of the lamellar pad

size: snout to vent length (SVL); body shape: trunk length (TRL), body width (BW), tail length (TL), width at tail base (TW), height of the tail at the base (TD), head length (HL), head width (HW), head height (HH), crus length (CL) and forearm length (FL); head shape: orbital diameter (OD), distance from eye to nostril (NE), distance from eye to tip of snout (OrbS), distance between eye and ear (OrbEar), length of the ear opening (EarL), distance between the nostrils (IN), intraorbital distance (IO), distance between ear and snout (EarS), length and width of the rostral scale (RosL and RosW), and length and width of the mental scale (MenL and MenW); and shape of the lamellar pad: length of the forelimb and hindlimb toepads (LFL1, LFL2, LFL3, LFL4, LFL5, LHL1, LHL2, LHL3, LHL4, LHL5) and width of the forelimb and hindlimb toepads (WFL1, WFL2, WFL3, WFL4, WFL5, WHL1, WHL2, WHL3, WHL4, WHL5). The toepad measurements were taken under a Leica stereomicroscope using a scale and later measured using the software ImageJ. Museum specimens were measured using photographs of the toepads along with a scale.