The Centre for Ecological Sciences (CES) was established in 1983 as India’s first department of ecology at a premier institution. Over the last four decades, CES has pioneered research in ecology, evolution and behaviour using a range of approaches from field and experimental ecology to theoretical and computational ecology.

To celebrate 42 years of CES, we are planning an event on ‘Ecology, Evolution and Everything’ on June 28, 2025. Join us for a series of talks, panels, posters, displays and enjoyable conversations about all things ecology and conservation.

Semi-arid ecosystems often exhibit irregular spatial vegetation patterns that result from complex ecological feedback. Research suggests that these patterns may serve as indicators of ecosystem resilience. While theoretical and modelling studies have explored these patterns at length, empirical validation, especially using temporal data, is limited. This thesis aims to bridge that gap by examining the patterns and dynamics of vegetation clusters across African and Indian drylands.

      In the first chapter, we analyse semi-arid sites in sub-Saharan Africa using high-resolution satellite-derived NDVI data. We look into steady-state spatial patterns. And also look into temporal changes in vegetation clusters, and fit statistical models to cluster-size distributions.
      In the second chapter, we extend this approach to 20 semi-arid sites in India. Additionally, I examine how rainfall, fire, and soil properties influence cluster dynamics and whether similar patterns evolve across continents.
      In the third chapter, we plan to evaluate the effectiveness of freely available versus paid high-resolution satellite datasets for spatial early warning detection. Then, compare metrics derived from both data types and assess their utility in accurately characterising vegetation patterns. This analysis aims to determine whether low-cost solutions can be scaled up for global dryland monitoring.

Finally, we plan to propose a predictive framework for ecosystem resilience that integrates high-resolution vegetation cluster statistics with environmental data. We aim to predict the vegetation patterns based on future climate change scenarios, with the aim of identifying and prioritising areas for management and conservation purposes.

Colour takes on diverse forms and serves important, versatile functions in the lives of animals. Consequently, animal colouration is influenced by various physiological, ecological and evolutionary factors. Members of the family Agamidae are known to use their elaborate colouration in contexts like courtship, competition, camouflage, and thermoregulation. Some species are also able to actively modulate and change the expression of their colours in response to shifting contexts. However, this fascinating group of colourful lizards, especially species found in India, remains poorly studied. This thesis aims to uncover the factors that influence the form and function of colours in agamids.
Even well-intentioned conservation efforts can have unintended consequences. In my first chapter, I study how vulture restaurants can have a cascading effect on the physiology, colour, and morphology of the vulnerable Indian spiny tailed lizard (Saara hardwickii) by inadvertently increasing its exposure to predators.
Did you know that CES’s most popular study organism, Psammophilus dorsalis, engages in colourful sleeptalking at night?! In my second chapter, I investigate why P. dorsalis expresses social colours at night in the absence of any obvious stimulus or social context. I test whether diurnal social interactions influence the nocturnal expression of social colours in this species.
Scaling up from these species-centric studies, my third chapter explores the evolution of colours in Asian and African agamids using a phylogenetic comparative approach. I will test the contribution of ecological factors such as habitat openness, microhabitat substrates and habit in shaping the evolution of colours on different body regions of species in these clades.
While most agamids are content with having a fixed set of colours, some Indian species love to change their colourful costumes as the occasion demands. In my final chapter, I explore the evolutionary drivers behind rapid colour change in Indian agamids and quantify its spectral extent. I also investigate the thermoregulatory trade-offs associated with expression of social colouration in these species.
Overall, this thesis will help unravel various intricacies of colour evolution and highlight the intriguing role it plays in the lives of agamids.

Biodiversity is distributed unevenly across the globe. As human-driven environmental change accelerates, understanding the processes that generate and maintain this diversity has become more urgent than ever. Despite decades of research, key questions remain: Why is biodiversity concentrated in certain regions and clades? What mechanisms allow it to persist over time? And how vulnerable is it to the unprecedented pressures of a rapidly changing world? Recent advances in computational power combined with centuries of natural history collections, cutting-edge remote sensing technologies, and global citizen science initiatives now enable us to map and study biodiversity in ways that were once unimaginable. My research leverages these advancements to unravel the complex processes shaping diversity patterns, both across and within species, and to better predict the challenges posed by rapid environmental change. In this talk, I will share three key insights from my research using global datasets to examine the past, present, and future of biodiversity.
First, I will examine how macroevolutionary and macroecological processes have shaped the distribution of evolutionarily unique and geographically rare species, emphasizing the role of mountains as cradles of biodiversity. Second, based on long-term resurvey data, I will present evidence that temperate species have already experienced more warm-edge local extirpations due to ongoing climate change than tropical species, challenging long-standing assumptions about the vulnerability of tropical species to climate change. Finally, I will show how the rising frequency, duration, and intensity of short-term extreme heat events (i.e., heatwaves), driven by climate change, are likely to reshape biodiversity patterns in the future.

Recent genetic research has shown that the present-day population of the Indian subcontinent derives its ancestry from at least three major sources: early agriculturalists from the Iranian plateau, pastoralist groups originating in the Pontic-Caspian steppe, and ancient hunter-gatherers with affinities to the Andamanese. The current genetic landscape of India represents a cline resulting from admixture among these sources. However, with growing availability of ancient and modern genome sequences and advanced population structure analyses, a more nuanced picture of ancestry is beginning to take shape.
In this study, we focus on Dravidian-speaking populations and propose the existence of a fourth ancestral component. This component appears to have diverged from the basal Middle Eastern lineage that contributed to the Iranian agriculturalist ancestry. Supported by the Elamo-Dravidian hypothesis and linguistic phylogenies within the Dravidian language family, our genetic findings suggest a coherent link between language and ancestry.
Our analyses identify this unique ancestry—termed ‘Proto-Dravidian’—within the Koraga tribe, suggesting its emergence around the early period of the Indus Valley Civilization. This ancestry is genetically distinct from the previously described sources and is estimated to have originated at least 4,400 years ago in the region stretching between the Iranian plateau and the Indus Valley. The presence of this component across contemporary Indian populations, with the exception of some tribal groups, underscores its enduring influence.
This discovery highlights the critical role of fine-scale, population-specific studies in reconstructing ancestral histories. It also calls for carefully designed sampling strategies in genomic biobanking to avoid oversimplified models of ancestry. Moving forward, an interdisciplinary approach will be essential to unravel the complexities of human population history in South Asia.

Metabolicaly-driven interactions between biological species in any local ecosystem typically form large, complex networks that generate interesting and often unpredictable system dynamics. A new Mount Everest for theoretical biology, with a wide range of applications, is the development of methods to control and engineer these complex, nonlinear systems. To this end, we need to understand a fundamental problem that has occupied Biologists, and in particular, Ecologists, for almost two centuries: how do these seemingly improbable systems assemble and persist in (an increasingly) fluctuating and uncertain real world? In this talk, I will outline the challenge, and present recent progress towards the goal of engineering microbiomes under a ubiquitous source of environmental fluctuations: temperature.

Elevational migration is the seasonal movement of organisms between higher-elevation breeding grounds and lower-elevation wintering grounds. Amongst montane bird species, elevational migration is a common phenomenon, with nearly 70% of high elevation species in Himalayas showing this behaviour. Yet, most bird migration studies focus on long-distance latitudinal migration and most of our current understanding of elevational migration and it’s drivers come from studies from neotropical mountains where most migrants are frugivorous, unlike the mostly insectivorous migrants of the rest of the world. I aim to understand how birds migrate in the Himalayas and how resource availability and dietary specialisation can explain elevational migration in Himalayan Birds.
In the first chapter I use a large citizen science dataset (eBird) to determine the sumer and winter elevational ranges of 377 Himalayan bird species and describe five elevational migration patterns. I then examine how diet, habitat, territoriality, mass and wing morphology can best explain these patterns.
In the second chapter I attempted to understand how arthropod availability varies seasonally along the Himalayan elevation gradient. Aerial and terrestrial arthropods decline with elevation in the winter but increase with elevation in the summer while foliage arthropods show a similar mid-elevation peak in abundance across seasons. I then correlate these patterns with the abundances of different functional guilds of birds to determine of food availability may drive elevational migration.
In the third chapter, using a combination of faecal DNA metabarcoding and stable isotope analysis, I examine whether dietary specialisation can explain why some high elevation breeding birds migrate to lower elevations in winter (where arthropods abundances do not fluctuate) while others overwinter at high elevations winter despite the lack of arthropod resources.
In summary, using a combination of citizen science datasets, field and lab-based methods, my thesis attempts to improve our understanding of elevational migration in the Himalayas and the drivers of this movement. Understanding how temperature, seasonality and diet drive altitudinal migration will be a crucial first step in predicting how tropical montane avifauna will fare in an increasingly warm world.

The distribution of plants and animals across the globe raises a key question: why are species found where they are, and why not elsewhere? To attempt this roughly 200-year-old question requires the study of different ‘levels’ – for instance, from how the population density (the abundance) of a species is structured across its range to how the extent of a species’ occurrence (the range) influences large-scale patterns of species richness. This PhD aims to understand the macroecological patterns and processes of species diversity and distribution using a three-layered approach.

At the largest level, what drives patterns of species richness? For the first two chapters, we build simulation models to understand i) the influence of range properties on cross-taxa species richness patterns and ii) how eco-evolutionary processes drive extant range and richness patterns.

Given that species can be rare along two dimensions, namely abundance and range size, which traits determine rarity? In the third chapter, we study how the interactions between habitat specificity, habitat availability and competition affect the abundance and range sizes of woody plants of the Western Ghats.

At the smallest level, what influences the distribution of abundance across a species’ range? In the final chapter, we attempt to understand the spatial patterning of abundance of select woody plants of the Western Ghats using a combination of modelling and field surveys.

Overall, this thesis will provide new insights into patterns of richness, range size and abundance and their underlying drivers in tropical biodiversity hotspots.

Mutualism involves exchange of services and rewards between partners, resulting in a net benefit to those involved. In many mutualisms, hosts are larger partners that interact with several individuals of smaller mutualists that live on or within them and are termed symbionts. Partners have an incentive to cheat, leading to possible breakdown of the mutualism. Hosts may regulate interaction by selectively rewarding cooperative symbionts. However, this host-centric view that has dominated mutualism studies, does not explain the role of symbionts in regulating trade within a mutualism. In a mutualism with physiological connection between the host and the symbionts, it is necessary to understand whether the symbionts can influence the resources they receive from hosts. My thesis is an attempt to understand resource allocation patterns and the strategies employed by both partners in a prominent brood-site pollination mutualism between fig trees and their pollinating fig wasps which develop within an enclosed inflorescence termed a syconium.
We determined the pattern of resource partitioning to different components of the fig syconium. We tested the applicability of theories describing resource allocation at the whole plant level to individual organs like the syconium. Results show that the syconial wall, that provides protection to occupants, makes up the majority of the dry mass of a syconium, although it is nutritionally less demanding. Further, a single pollinator wasp is costlier to produce compared to a single seed. We showed that there is no number–mass trade-off for both seeds and pollinator wasps indicating proportional allocation of resources to a syconium.
We measured the elementome of seeds, pollinators and the syconial wall tissue and determined the biogeochemical niche (BN) of syconium occupants by examining concentrations of many important elements. We found that the BN of seeds and pollinators are significantly different suggesting differential nutrient demands and demonstrating how coexistence is possible for seeds and pollinators within the syconium microcosms.
We attempted to understand if individual differences in composition of seeds and pollinators result in differential allocation of resources to the syconium. We experimentally manipulated pollinators (foundresses) to produce syconia containing only seeds (S), only pollinators (G) and both seeds and pollinators (SG). We found that overall, the presence of both seeds and pollinator galls increased resource
allocation to a syconium. Since pollinators are gallers, we attempted to understand the role of plant growth hormones in the differential effects of seeds and pollinators on resource allocation. We measured the concentrations of indole-3-acetic acid (IAA), an auxin and trans-Zeatin (tZ), a cytokinin, in S, G and SG syconia during early and mid-phases of their development. We found that IAA and tZ concentrations did not differ between S and G syconia suggesting that galls mimic seeds to garner resources. Further, SG syconia had higher hormone levels correlating with its increased size reported in the previous chapter. Syconia that contain both seeds and galls are rewarded with more resources, which can also ensure cooperation between the partners.

It’s true that having first aid training undoubtedly helps save lives. That’s not all though; giving appropriate first aid immediately can help to reduce a person’s recovery time and make the difference between the patient having a temporary or long-term disability. Not all accidents, injuries or illnesses require a trip to the hospital but it doesn’t mean they don’t cause pain and suffering to the patient, even just by employing simple techniques such as applying an ice pack correctly, or utilising appropriate bandaging, you’ll help to relieve their discomfort. First aid training will make you confident and comfortable and therefore more effective and in control when you need to be.