The stability and complexity of communities depend on an intricate network of interactions within ecosystems. Trophic food webs demonstrate interactions between producers and consumers at various levels in ecological ecosystems. A significant part of terrestrial biodiversity is plants, phytophagous insects, and their natural enemies, such as parasitoids and predators. Despite being a significant presence in terrestrial insect communities, the roles and diversity of parasitoids are not well known due to limited research on tri-trophic interactions, particularly in the tropics. In this study, I will identify and contrast plant-herbivore-parasitoid food webs within the Rutaceae family of plants across wild and cultivated environments.
Chapter 1 focuses on collecting and identifying lepidopteran herbivores (butterflies and moths) and their parasitoids on Rutaceae across multiple study sites. To determine the trophic interactions, insects must be collected during all seasons and parasitoids reared from hosts collected at all immature life stages. This chapter will also determine the life histories of each parasitoid.
In Chapter 2, I will construct and analyse the food webs on Rutaceae, from their wild native setting and under varying management practices. This will show the difference in species interaction between wild and cultivated Rutaceae, as well as the effect of agricultural practices on trophic interactions. This chapter will also identify the diet range of each consumer.
Chapters 3 and 4 are focused on experimental studies to identify the contributions of selected biotic interactions in shaping the food webs from the different sites. Chapter 3 addresses food preferences and performance of the butterflies and parasitoids. Chapter 4 addresses the impact of ant predation of the lepidoptera in the food webs.
Chapter 5 is on the application of this study to Butterfly Parks. I will develop guidelines for managing butterfly rearing at the Bannerghatta Butterfly Park and create displays about the diversity of insects on Rutaceae plants, trophic interactions amongst them in the Butterfly Park, and parasitoid natural history.
These research questions offer an integrated approach of both ecology and agriculture to understand the trophic interactions occurring in the Rutaceae plant family under a range of ecological conditions.

Fitness landscapes are a paradigm to understand how evolution proceeds. Yet such landscapes are only implicit about ecology and the diverse underlying communities in which organisms naturally thrive. In this talk, we show two concrete examples of how being part of an interacting community fundamentally alters evolutionary trajectories. Using bacterial communities as model systems, we show in one case how a species evolves in response to antibiotics depends on its interactions with another strain. In fact tuning this interaction can allow us to control how and whether antibiotic response evolves in the same environmental conditions. In the other case we show that sulfur cycling "pink berries" comprising diverse bacterial communities show remarkably slow down co-evolution due to strong mutualistic interactions in the community. In both cases, we show that simple mathematical models of community eco-evolutionary dynamics can capture our observations, and make new testable predictions. Our work highlights how ecological interactions can control evolutionary trajectories in bacterial communities.

Strikingly regular, large-scale patterns of vegetation growth were first documented by aerial photography in the Horn of Africa circa 1950 and are now known to exist in drylands across the globe.  The patterns often appear on very gently sloped terrain as bands of dense vegetation alternating with bare soil, and models suggest that they may be a strategy for maximizing usage of the limited water available.  A particular challenge for modeling these patterns is appropriately resolving fast processes such as surface water flow during rainstorms while still being able to capture slow dynamics such as the uphill migration of the vegetation bands, which has been observed to occur on the scale of a band width per century.  We propose a pulsed-precipitation model that treats rainstorms as instantaneous kicks to the soil water as it interacts with vegetation on the timescale of plant growth.  We use a stochastic rainfall model with the influence of fast storm-level hydrology captured by the spatial distribution of the soil water kicks.  The model allows for predictions about the influence of storm characteristics on the large-scale patterns.  Analysis and simulations suggest that the distance water travels on the surface before infiltrating into the soil during a typical storm plays a key role in determining the spacing between the bands. 

Phages, or viruses that infect bacteria, are often seen as perfect predators: they hijack their host's cellular machinery to replicate, ultimately killing the host to release new viral progeny. However, certain (temperate) phages can also initiate lysogeny—a latent infection where the viral genome integrates into the host genome, forming a prophage which replicates when the host cell divides. While lysis is an antagonistic host-parasite interaction, lysogeny can be viewed as mutualistic.

Although one might expect lysis to confer higher fitness to the virus due to rapid offspring production, lysogeny remains prevalent across diverse ecosystems, including oceans, soil, and host-associated microbiomes. For instance, conservative estimates suggest that about a fifth of marine bacterial cells harbor prophages. This prevalence highlights the need to understand the ecological drivers of being temperate and the influence of lysogeny on microbial communities.

In this talk, I will first present a theoretical framework for comparing the fitness of lytic and lysogenic viral strategies. I will discuss past work that identifies conditions where lysogeny can outperform lysis in the short-term. Additionally, I will introduce a mathematical framework I developed to explore the eco-evolutionary dynamics of temperate phages over the long-term. In particular, I will demonstrate how periodic environmental changes, such as diurnal or seasonal shifts, can create conflicting selection pressures on different timescales, which ultimately favor intermediate strategies between obligate lysis and obligate lysogeny. Finally, using an environmentally relevant phage-bacteria system, I will show how lysogeny affects microbial communities by enabling multiple phages to coexist with a single host population, in apparent violation of the competitive exclusion principle.

There is an unprecedented urgency in mitigating the impacts of climate change and forest restoration strategies are at the forefront. Global and national scale environmental policy fora have championed the cause of forest restoration as an important nature-based solution, culminating in the UN Decade of Ecosystem Restoration. Also, it has often been touted as a cost-effective and scalable panacea with the potential to deliver a variety of benefits beyond sequestration of carbon. However, the reality of this strategy is complex. In this talk, I will weave the opportunities and realities of forest restoration as a viable strategy for climate change mitigation and other ecosystem benefits in India. I will highlight the potential of forest restoration as a ‘Natural Climate Solution’, the realities of forest restoration in areas that climatically host savannas and forests and the trade-offs and synergies in Nature’s Contributions to People from forest restoration programs across India

Accelerating climate change as a result of anthropogenic activities continues to have a profound impact on ecosystems worldwide. Particularly vulnerable are the thermally sensitive flora and fauna of tropical mountains. Mountain ecosystems can therefore serve as in situ models to study the effects of climate change on biological communities. While innumerable studies have reported local extinctions of species and overall loss of biodiversity from across the globe, loss of biotic interactions also deserves attention. One of the most striking examples of networks of multi-species interactions is exemplified by mixed species flocks (MSFs). MSFs are groups of birds belonging to two or more species that forage and move together. MSF participants benefit from easier access to food resources and predator avoidance, which in turn influences the fitness of participant individuals. In this study, I examine how the composition and properties of MSF networks change along an elevation gradient. We observe a general decline in network structure with increasing elevation with some anomaly at around 1600m. I also attempt to correlate the composition of arthropods (such as flying insects, foliage insects) with the composition of MSF in terms of species with different foraging techniques.

Ants are ubiquitous, hyper-diverse, and one of the oldest venomous arthropods on earth. They belong to the order Hymenoptera, which also includes sawflies, bees, and wasps. Ants, wasps, and bees share a common ancestor – a stinging wasp-like organism – and constitute the aculeata lineage. In Hymenoptera, females have modified their ovipositor into a stinger, which is connected to the venom gland, Dufour’s gland, and, in queens, to the ovaries. Venom, a cocktail of proteins, peptides, salts and amino acids, is an adaptive trait in certain organisms to fulfil their function like predation, defence from predators and microbes, and competition.  

While several venomous arthropods, such as wasps, scorpions and spiders, have been studied due to their medical relevance, ant venom cocktails are relatively untapped. Most studies on hymenoptera venoms are restricted to honeybees and wasps, while very few have focused on a handful of ant species, such as fire ants and giant red bull ants. My thesis aims to investigate Indian ants and shed light on their enigmatic and unexplored venoms.

My first chapter employs a proteo-transcriptomic approach to explore the venom of Indian ants: Tetraponera rufonigra (Bi-coloured arboreal ant), Myrmecaria brunnea (Brown Hunchback ant), Leptogenys processionalis (Razorjaw ant), and Diacamma indicum (Indian Queenless ant). These ant species were selected considering their habitat, ecological function, and evolutionary position. This chapter will unveil the composition of venom and how it is shaped by its deployment in distinct ecological contexts.

Seasonality is a major driver for several traits in arthropods, mainly due to their inability to maintain homeostasis, unlike vertebrates. The second chapter focuses on the plasticity of ant venom. By integrating proteo-transcriptomics and free amino acids profiling, this chapter will examine how seasonal changes influence venom composition and amounts. These findings will reveal how ants modify their venom cocktail to survive and thrive in fluctuating environmental conditions.

Eusociality, the division of labour within a colony, has evolved multiple times in the animal kingdom and has underpinned the evolutionary success of several lineages. An ant colony is divided into different casts like queen, worker (in some cases, major and minor workers) and drone. My third chapter will attempt to investigate the intra-colony venom variation across different working classes (casts). The results of this chapter will elucidate the influence of task specialisation on ant venoms.

Together, my thesis provides the first comprehensive analysis of Indian ant venom composition, highlighting its ecological, seasonal, and evolutionary dynamics. This study will open new avenues for future exploration in ecology, evolution, and biodiscovery research.

Understanding the generation and maintenance of diversity—both in lineages and traits—is a central goal of macroevolutionary research. Hemidactylus geckos are well-suited for exploring such questions due to their remarkable species richness and trait variation. Despite their potential, studies on the broader patterns within the genus are rare. My thesis fills this gap by dwelling into key macroevolutionary processes such as biogeography, diversification, and trait evolution in Hemidactylus by utilizing various phylogenetic comparative methods.

In chapter one, I reconstruct the most updated global phylogeny of Hemidactylus geckos using coalescent and concatenation-based methods. Further, I unravel their disputed biogeographic origins and highlight the intercontinental dispersal events that may have shaped the current diversity and distribution of the genus.

Chapter two utilizes a trait-based approach to explain the contrasting pattern of species richness and distribution between Hemidactylus and its sister genus Dravidogecko. I evaluate the effect of various abiotic and morphological characters on the dispersal ability and diversification rates of these two groups.

In Chapter three, I seek to investigate the impact of habitat use on body size and morphological evolution of the genus. I use various trait evolution models to determine whether habitat filtering drives size variation, and further attempt to quantify the strength of selection.

Finally, chapter four focuses on the ecological and evolutionary dynamics of host-parasite interactions between Hemidactylus geckos and their ectoparasitic mites. I ask whether mite communities are predominantly shaped by host phylogeny or geography, and further attempt to uncover the ecological correlates of mite loads in these geckos.

These research questions thus offer a multifaceted understanding of the evolutionary forces driving the complex trajectories of such widely distributed, highly speciose taxa.

All animals behave. Behaviour allows animals flexibility in dealing with heterogeneous, dynamic environments, and a key goal of the field of animal behaviour is to understand how, when, and why animals do what they do. To better understand behaviour, we can view it as a sequence of discrete behavioural states driven by a behavioural algorithm, a set of principles based on which an animal performs behavioural decision-making. I adopt a multi-time-scale perspective to explore behavioural algorithms from three species of mammals in the wild: meerkats (Suricata suricatta), white-nosed coatis (Nasua narica), and spotted hyenas (Crocuta crocuta), whose behaviours I inferred using accelerometer data. In this talk, I will demonstrate long time-scale structure in the behavioural sequences of all collared individuals of all three study species, showing that behaviour depends on past states of the animal much more than expected from any simple (i.e., Markovian) model of behaviour. This work is likely the most detailed description of long-time-range behavioural structure in wild-living animals reported in the literature. I will then highlight specific behaviours at a slow and a fast temporal scale, considering the 24 h activity patterns of the hyenas and the moment-to-moment vigilance dynamics of the meerkats, and explore various factors, especially social ones, that influence behavioural decisions at these scales.

Globally, opportunistic scavengers, such as kites, macaques, street dogs and livestock, often partake of the human niche, showcasing variable adherence to human norms and practices. The integration of nonhuman species into modern urban settlements thus marks a significant shift in human–animal proximities, akin to the transformative impacts of agriculture. Our research in Delhi focuses on the eco-evolutionary processes that underpin cross-species co-cultural ties, with animals exploiting food subsidies from garbage and ritual feeding practices. We study how inter- and intra-specific interactions along the urban gradient give rise to behavioural innovations in response to the predictable dispersion of such food subsidies. These interactions often involve significant adaptations or co-option of behavioural and morphological traits, influencing nonhuman social dynamics and population structures. Tropical cities, where urbanisation is a continuous process, offer quasi-experimental opportunities to examine shifts in population- and species-specific socialities in aerial, arboreal, and ground-dwelling commensals. Historically, these interactions have resulted in wildlife providing important services to humans. Unfortunately, however, such interactions can also easily turn negative, such as when actions aimed at promoting nonhuman lives lead to human–animal conflict, loss of property and invaluable lives of all contestants, and the spread of zoonotic diseases. Interestingly, human–nonhuman coexistence in South Asia represents a distinctive fusion of adopted Western infrastructure and a unique Indian ethos. This talk will emphasise why transdisciplinary methodologies are indispensable to comprehend coexistence, while designing and administering vibrant and ‘animated’ tropical cities.