Evolutionary diversification of alpine ginger reflects the early uplift of the Himalayan–Tibetan Plateau and rapid extrusion of Indochina

Abstract

The evolutionary diversifications of many taxonomic groups, especially those with limited dispersal ability, are often driven by key geological events, such as tectonic drift, continental collisions, and uplifts of mountains. Here, we use full range geographic sampling to create a dated molecular phylogeny for two genera of alpine gingers (Cautleya and Roscoea) in the Pan-Himalaya, and test the correlations between evolutionary diversification of this group and major geological events in the studied region. Our results revealed that the origination of their common ancestor and evolutionary split between the two genera occurred during the middle Eocene and the late Eocene to the early Oligocene, corresponding well to the proposed two early uplifts of the Himalayan–Tibetan Plateau. Roscoea species, the highest elevation gingers known, were then divided into distinct Himalayan and Indochinese clades, simultaneous with the rapid extrusion of Indochina and accompanied by the third Himalayan uplift around the Oligocene/Miocene boundary. This study highlights the importance of evolutionary diversification of plants as an independent line of evidence to reflect tectonic events in the Himalayan–Indochinese region.