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Repeated evolution of terrestrial lineages in a continental lizard radiation
Author(s) -
Lajmi Aparna,
Verma Anjali,
Karanth K. Praveen
Publication year - 2020
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/jeb.13544
Subject(s) - biology , adaptive radiation , lineage (genetic) , diversification (marketing strategy) , ecomorphology , evolutionary biology , ecology , habitat , phylogenetic tree , phylogenetics , gene , biochemistry , marketing , business
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 Hemidactylus 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 Ornstein‐Ulhenbeck 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.