Globetrotting geckos: Historical biogeography suggests an Indian origin and “Out-Of-India” dispersal for the cosmopolitanHemidactylusgeckos

Abstract

AimFollowing the breakup of Gondwana, dispersal events both into and out of India have influenced the biotic assembly of the surrounding landmasses. The cosmopolitanHemidactyluspresents an intriguing group to examine these instances, particularly given its sister relationship with the endemicDravidogeckofound in India’s Western Ghats. Despite earlier theories of Afro-Arabian or Southeast Asian origins forHemidactylus, its deep divergence fromDravidogecko(∼57 million years ago) suggests a potential Indian origin, thus contradicting an “Into-India” scenario proposed for the current Indian tetrapod groups. We thus aim to resolve the origins and shed light on the inter-continental dispersals inHemidactylusby reconstructing its biogeographic history.LocationWorldwideTaxonHemidactylusGeckosMethodsWe use six nuclear genes to reconstruct a reduced representation backbone phylogeny ofHemidactylususing likelihood, Bayesian, and coalescent based methods. We further assemble a timetree using a concatenated dataset of nuclear and mitochondrial markers from 132 of the 192Hemidactylusspecies by constraining the topology with the backbone phylogeny and secondary calibrations. We use this chronogram to reconstruct ancestral geographic ranges using BioGeoBEARS, employing a time-stratified approach in conjunction with plate tectonics information to explicitly test four hypotheses regarding the origin of the genus — An Indian origin, a Southeast Asian origin, a Saharo-Arabian origin, or an Afrotropical origin.ResultsOur findings suggest that the ancestral lineage ofHemidactylusandDravidogeckocolonized the drifting Indian plate from Southeast Asia approximately 57 million years ago, eventually evolving into the two genera in the Indian subcontinent. Following this,Hemidactylusdispersed multiple times from India to Africa and Asia.Main ConclusionThis study proposes an Indian origin for these widely distributed geckos, representing a rare instance of an “Out-of-India” dispersal scenario observed in a non-Gondwanan squamate group. Additionally, our research underscores the significance of incorporating sister taxa in biogeographic analyses to avoid misinterpretations of ancestral ranges.