Himalayan upliftment and Shiwalik succession act as a cradle for divergence in Bengal monitor lizard Varanus bengalensis (Reptilia: Varanidae) in India.

Abstract

The Himalayan foothills and associated environment are well-known for driving the rapid diversification of many species and the formation of biodiversity hotspots. The effects of environmental change since the Miocene have accelerated species diversification, and hence are useful for studying population genetic structure, and evolutionary relationships via genetic approaches. To date, the effects of climatic fluctuations on the biogeography of large-bodied lizards have not been assessed comprehensively. Herein, we examine the diversification of Varanus bengalensis, focusing on its genetic structure to provide insights into how landscape structure and climatic fluctuations have shaped species differentiation. We confirm the existence of two distinct lineages within V. bengalensis distributed across the Himalayan foothills and the remainder of mainland India. Divergence analyses revealed the split between the Himalayan foothills and the remainder of the mainland lineages of V. bengalensis in the mid-Pliocene ~3.06 Ma, potentially as a consequence of the Siwalik broadening and climatic fluctuations across the Himalayan foothills. The results suggest recognition of a new lineage of V. bengalensis from the Himalayan foothills as a distinctive evolutionarily significant unit.