The biota of the Indian subcontinent was assembled through multiple associations with various landmasses during a period spanning the Late Cretaceous to the present. It consists of Gondwanan elements that subsequently dispersed ‘out-of-India’ and biota that dispersed ‘into-India’ after the subcontinent collided with Asia. However, the relative contribution of these connections to the current biotic assembly of the subcontinent has been under-explored. Our aim here was to understand the relative importance of these various routes of biotic assembly in India by studying the historical biogeography of the tropical Old World freshwater snail genus Pila. We reconstructed a near-complete phylogeny, based on nuclear and mitochondrial markers, of Ampullariidae including all the described Pila species from India and Ampullariids worldwide. Thereafter, molecular dating and ancestral range estimation analyses were carried out to ascertain the time frame and route of colonization of India by Pila. The results showed 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 took place between Southeast Asia and India. These findings corroborate increasing evidence that much of the current Indian assemblage of biota actually dispersed ‘into-India’ after it collided with Asia.
The Indian subcontinent has experienced numerous paleogeological and paleoclimatic events during the Cenozoic which shaped the biotic assembly over time in the subcontinent. The role of these events in governing the biotic exchange between Southeast Asia and Indian subregion is underexplored. We aimed to uncover the effects the collision of the Indian and Asian plate, marine transgression in the Bengal basin as well as the paleoclimatic changes in the subcontinent and adjoining regions, on the dispersal of freshwater snail family Viviparidae from Southeast Asia (SEA) to Indian subregion. Extensive sampling was carried out throughout the Indian subcontinent to capture the current diversity of the targeted lineages. Three mitochondrial and two nuclear markers were sequenced from these samples and combined with published sequences to reconstruct a near complete global phylogeny of Viviparidae. Molecular dating and ancestral range estimation were undertaken to obtain the time frame for the dispersal events. Results from these analyses were contrasted with paleoclimate and paleogeology to better understand the biogeography of Indian viviparids. Results support at least two dispersal events into India from Southeast Asia. The earlier event is likely to have occurred during a warm and humid Eocene period before a permanent land connection was established between the two landmasses. While the more recent dispersal occurred post-suturing and overlapped with a time in late Tertiary to Quaternary when arid climate prevailed. However, we could not firmly establish how the marine transgressions influenced the dispersal events. Even though most biotic exchange between India and SEA are noted to be post-suturing, our results add to a growing body of work that suggests faunal exchange pre-suturing probably mediated by intermittent land connections.
The history of a lineage is intertwined with the history of the landscape it inhabits. Here we showcase how the geo-tectonic and climatic evolution of South Asia and surrounding landmasses have shaped the biogeographical history of Indoplanorbis exustus, a tropical Asian, freshwater snail. We amplified partial COI gene fragments from all over India and combined this with a larger dataset from South and Southeast Asia to carry out phylogenetic reconstruction, species delimitation analysis and population genetic analyses. Two nuclear genes were also amplified from a few individuals per putative species to carry out divergence dating and ancestral area reconstruction analyses. The results suggest that I. exustus dispersed out of Africa into India during the Eocene. Furthermore, molecular data suggest I. exustus is a species complex consisting of multiple putative species. Primary diversification took place in the Northern Indian plains or in Northeast India. The speciation events appear to be primarily allopatric caused by a series of aridification events starting from the late Miocene to early Pleistocene. None of the species appears to have any underlying genetic structure suggestive of high vagility. All the species underwent population fluctuations during the Pleistocene, probably driven by the Quaternary climatic fluctuations.
The history of a lineage is intertwined with the history of the landscape it resides in. Here we showcase how the geo-tectonic and climatic evolution in South Asia and surrounding landmasses have shaped the biogeographic history of Indoplanorbis exustus, a tropical Asian, freshwater, pulmonated snail. We amplified partial COI gene fragment from all over India and combined this with a larger dataset from South and Southeast Asia to carry out phylogenetic reconstruction, species delimitation analysis, and population genetic analyses. Two nuclear genes were also amplified from one individual per putative species to carry out divergence dating and ancestral area reconstruction analyses. The results suggest that Indoplanorbis dispersed out of Africa into India during Eocene. Furthermore, molecular data suggests Indoplanorbis is a species complex consisting of multiple putative species. The primary diversification took place in Northern Indian plains or the Northeast India. The speciation events appear to be primarily allopatric caused by a series of aridification events starting from late Miocene to early Pleistocene. None of the species seemed to have any underlying genetic structure suggestive of high vagility. All the species underwent population fluctuations during the Pleistocene likely driven by the Quaternary climatic fluctuations.
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.
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