Relationships within and between the land snail faunas of the Southern and Northeast Deccan Plate Hotspots

For about half a million years beginning near the end of the Cretaceous, massive outflows of low-viscosity lava spread over vast areas of the Indian or Deccan Tectonic Plate to form the Deccan Traps. This would have had a devastating impact on the Deccan Plate biota and been a major influence on global climate. At the very least, Deccan Trap formation would have been a massive vicariant event isolating the southern and northern extremities of the Deccan Plate biota before land contact with Asia was thought to have been established around 30 million years ago.

Because of their possession of shells, potential for fossilization, and often-poor powers of dispersal, land snails are invaluable tools for investigating evolutionary and faunal changes across a wide spectrum of scales. These range from distribution shifts in response to ephemeral changes in habitat to current distributions that have their origins in Mesozoic plate tectonic events. In addition to well-established molecular markers for investigating relationships at species level and below, our molecular studies on land snails have demonstrated that it is now possible to investigate deep evolutionary relationships, address major questions in historical biogeography and make significant progress in unravelling the deep history of land snail evolution.

This project will look at the biodiversity hotspot snail faunas from the northern (Nepal) and southern (Sri Lanka) limits of the Deccan Plate to address two main questions:

  • What is the relationship of the northern Deccan Plate biota to the biota of the southern Deccan Plate and can the origin of any northern taxa be linked to a K/T vicariant event?
  • Both of our study areas on the southern and northern Deccan Plate are recognised as global biodiversity hotspots. Do the genetic distances and relationships between taxa lend support to the hypothesis that this diversity has arisen over long periods of time (tens of millions of years) or to the hypothesis that most high diversity faunas represent dynamic species turnover with most sister species having diverged within the past few million years (5 or fewer Ma), or is the picture more complex?

Information on our faunal work in south Asia can be found on our tropical land snails project page. By using the potential of land snails for understanding historical events and relationships we can contribute to an informed basis for recognising conservation priorities and long-term projections of future prospects, particularly for the highly diverse but poorly known invertebrate component of the regions fauna.


Fred Naggs ( and  Christopher Wade (Institute of Genetics, University of Nottingham).

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