Into-India or out-of-India? Historical biogeography of freshwater gastropod genus Pila (Ampullariidae)

Abstract

The biota of the Indian subcontinent has assembled during various points of the history of its continental drift: some when it was still a part of Gondwanaland and subsequently dispersed 'out-of-India' and some dispersed 'into-India' after it collided with Asia. However, the relative contribution of these connection to the current biotic assembly of the subcontinent is still under-explored. We aimed to understand the relative importance of these various routes of biotic assembly in India through studying the historical biogeography of tropical Old World freshwater snail genus Pila. We reconstructed a near-complete phylogeny of Ampullariidae including all the described Pila species from India and published sequences of Ampullariids from all over the world from two mitochondrial and two nuclear markers. Thereafter molecular dating and ancestral area reconstruction analyses were carried out in order to ascertain the time frame and route of colonization of India. The results suggest that Pila dispersed into India as well as other parts of tropical Asia from Africa after both India and Africa collided with Eurasia. Furthermore, multiple dispersals have taken place between Southeast Asia and India. The findings consolidate the rapidly building evidence that much of the current assemblage of biota actually dispersed into-India after it collided with Asia.