Twin Cradles of Diversity: Parallel In-Situ Radiations in India and Africa Drive the Evolution of Hemidactylus Geckos

Abstract

Aim

The dynamic geological history of the Earth, alongside dispersal and vicariance processes, has profoundly shaped global biodiversity patterns. The species-rich gecko genus Hemidactylus, with its nearly worldwide distribution, offers a compelling system to investigate these evolutionary processes. In this study, we aimed to resolve the long-debated origin of Hemidactylus and disentangle the directionality of its dispersal events, while identifying major centres of diversification across its range.

Location

Worldwide.

Taxon

Hemidactylus geckos.

Methods

We reconstructed a time-calibrated phylogeny of Hemidactylus using six nuclear and three mitochondrial genes, covering ~80% of described species, by employing both concatenation and coalescent-based methods. We then used a time-stratified BioGeoBEARS framework, informed by plate tectonics, to estimate ancestral ranges. To further account for phylogenetic and geographic uncertainty, we implemented biogeographic stochastic mapping to quantify the frequency and direction of dispersal, in situ speciation, and vicariance events.

Results

Our results supported an origin of Hemidactylus on the Indian plate around 58 million years ago, followed by a major dispersal into Africa. These two regions emerged as independent but parallel centres of in situ speciation. Subsequent dispersals led to a secondary diversification in the Middle East, and more recent colonisation events extended the genus's range into Southeast Asia and the Neotropics.

Main Conclusion

We propose an Indian origin for Hemidactylus and identify multiple hubs of diversification, notably in India and Africa. The genus's evolutionary success appears to have been shaped by directional, long-distance dispersal events combined with repeated in situ speciation. Together, these processes have enabled Hemidactylus to become one of the most widespread and speciose gecko genera.