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Ecology across space and time

Many have pondered over how the innumerable numbers of species, plants and animals alike, have come to be. Why are species around the world distributed in a particular manner? How does this contribute to large-scale diversity patterns? What kinds of relations exist within and between species? Why do two species, thought to be natural enemies, work together cooperatively?  These are some of the questions that Dr. Shanker and his research team are examining.

Situated in the lush green campus of IISc, Bangalore, Dr. Kartik Shanker’s lab is part of the Centre for Ecological Sciences. Community ecology is one of the fields of research in this lab. Here, they inquire about the assemblages of different species as well as relationships between them. For instance, it is well known that birds form loose groups, composed of different species, to obtain food. Which species form such “mixed species” foraging flocks, and why? Is it for foraging or anti-predation benefits? His student, Hari Sridhar’s PhD research showed that, on the whole, species are more likely to group with others that are similar to them, both in size and feeding habit. Another student, Anne Theo, is examining similar questions with reef fish.

Evolutionary biogeography is another field of enquiry within this group. In other words, they look at how the present distribution of organisms was shaped over evolutionary time; and how ancestral species have evolved and radiated to form the different species we see today, called “diversification”. One of the strengths of the lab is that they combine a range of field and lab-based techniques (such as computer modeling and genetic studies) to arrive at a conclusion. SP Vijayakumar, whose own PhD was on bushfrog diversification, led a large project on mapping the distribution of frogs, lizards and snakes in the Western Ghats. Their biogeographically based approach to sampling helped fill gaps in knowledge of species distributions, as well as unearth several new species in many genera. A field guide for frogs and lizards, and an online Atlas have been produced as part of this project.

Most of the research they carry out is in the Western Ghats and in coastal areas. But some of their projects extend to Northeast India. Ashok Mallik is studying snake biogeography and evolution, comparing the origin and dispersal of different genera, such as pit vipers, that extend across Eastern Ghats, Western Ghats and Northeast India. And Kesang Bhutia will soon initiate a study on plant diversity along elevation gradients in the Northeast.

Dr. Shanker has also been involved in projects on marine turtles for over 25 years. For his post-doctoral research, he studied the historical processes that maybe responsible for the current geographic distributions of olive ridley turtles on the east coast of India -- a field of research called “phylogeography”. His group has also been monitoring offshore, solitary and mass nesting populations of the vulnerable olive ridley turtle in Rushikulya (Orissa) for the last 8 years towards determining population trends. In marine turtles, eggs develop into males or females depending on the temperature of the nest – a phenomenon observed in other reptiles as well. One of the objectives of long term monitoring is to examine whether recent climate change related temperature variations have affected sex ratios. Other related projects include a study on the effects of artificial lighting on hatchlings.

Since 2008, the lab has also been monitoring leatherback turtle populations in Little Andaman Island, similar to the work in Orissa. This project includes satellite telemetry, and adult females fitted with transmitters have been tracked all the way to Australia to the East, and Mozambique and Madagascar to the West. In addition, they coordinate a national network on sea turtles, and provide support, training and capacity building to NGOs and other organizations that work with sea turtle populations along the Indian coast.

The lab works across a variety of taxonomic groups, from plants to vertebrates and invertebrates. They have also studied marine intertidal invertebrates, such as inter-tidal fauna, and coral reefs. Bharti, a PhD student works on gastropod phylogeography, while Dr. Naveen Namboothri, a Postdoc, works on the coral reef recruitment and resilience in the Andaman Islands.

One of the advantages of working with various taxa is comparisons can be made between groups. This may be useful in understanding what evolutionary and ecological processes are operating. “We can see what similarities and differences there are between taxa: for example, if there are similarities between forest birds and reef fish, then there must be some fundamentally important underlying ecological or evolutionary process at work”, says Dr. Shanker.

The lab has also taken up socio-ecological studies. They have researched the conflict between fishing communities and turtles, “which was part of a larger national project on human-animal conflict” says Dr. Shanker. In Orissa, they have been examining the attitudes of communities towards turtles, the origins of conflict and how political and social backgrounds may have influenced its development.

Presently, Dr. Shanker’s group has seven Ph.D. students, two postdoctoral fellows and about six project staff members, each contributing to the further understanding of the varied projects in the lab.

About the lab

Kartik Shanker is an Associate Professor at the Centre for Ecological Sciences, IISc.

Web: http://ces.iisc.ernet.in/kartik/

Email: kshanker@gmail.com; kshanker@ces.iisc.ernet.in

Phone: +91-80-2293-3104; +91-80-2360-0453