The Origin and Diversification of Turmerics ( <i>Curcuma</i> L.: Zingiberaceae) in Paleotropical Biodiversity Hotspots: The Role of Ancient Hybridisation and Historical Climate Change

ABSTRACT Aim To investigate the ecological and evolutionary mechanisms driving biodiversity in the Indo‐Malayan hotspots, with a particular focus on the roles of ancient hybridisation and historical climate in shaping species diversity. Location The Indo‐Malayan realm, particularly the Western Ghats‐Sri Lanka and Indo‐Burma biodiversity hotspots. Time Period The Miocene Climatic Optimum (~14 million years ago) to these days. Major Taxa Studied Curcuma (Zingiberaceae). Methods The evolutionary history of Curcuma was reconstructed using targeted nuclear loci. This genomic data was integrated with ecological niche modelling, biogeographic reconstruction and diversification dynamic analyses to examine the interplay between historical climate, niche evolution and hybridisation. Results Curcuma originated in the Indo‐Burma region approximately 14 Ma. Its diversification was likely promoted by prolonged periods of high humidity and relatively mild climatic conditions. Dispersal to the Western Ghats occurred during the mid‐Pliocene (3.6 Ma). Although ancient hybridisation may have facilitated ecological divergence and local adaptation, it did not have a statistically significant effect on diversification rates. Main Conclusions Our work provides support that the Indo‐Malayan biodiversity might be the result of species persistence enabled by extended periods of humidity and warm temperatures over evolutionary timescales, rather than increased speciation rates. These findings enhance our understanding of the processes shaping paleotropical biodiversity and offer insights relevant to the conservation and improvement of Curcuma , a crop of economic and medicinal value.