Soil microorganisms are the unseen majority in soil, that drive critical ecosystem processes, such as biogeochemical cycling of nutrients. For growth and metabolism, microbes require nutrients, which are either readily available as simple compounds or locked within complex macromolecules. To access these nutrients, microbes secrete extracellular enzymes into the soil matrix. This study focuses on three widely studied enzymes: β-glucosidase (BG, carbon-acquiring), N-acetyl-β-Glucosaminidase (NAG, nitrogen-acquiring), and phosphatase (AP, phosphorus-acquiring). Soil enzyme activity exhibits substantial spatial heterogeneity. To investigate the abiotic factors regulating enzyme activity at larger spatial scales, I compiled data from 54 published studies reporting enzyme activity in natural soils. I examined the effects of biome, edaphic factors (pH, organic carbon [SOC], total nitrogen [TN], total phosphorus [TP]), climatic factors (mean annual temperature [MAT], mean annual precipitation [MAP]), and geographic factors (elevation). Our results revealed that N-acquiring enzymes showed no significant differences across biomes, suggesting widespread nitrogen limitation. Conversely, C- and P-acquiring enzymes exhibited the lowest activity in desert soils, likely due to moisture limitations.

C acquiring enzyme activity was negatively affected by MAP, suggesting reduced carbon acquisition in wetter conditions, while SOC had a positive influence. NAG activity also decreased with increasing MAP but was positively influenced by elevation and TN, indicating enhanced nitrogen acquisition at higher elevations and with greater nitrogen concentrations in soil. For P acquiring enzyme, elevation and soil pH had negative effects, with reduced phosphorus acquisition at higher elevations and in more alkaline soils, whereas SOC positively influenced P acquiring enzyme activity. This study highlights the complex interplay of biotic and abiotic factors regulating soil enzyme activity across spatial gradients. Further research could explore additional factors or interactions to refine our understanding of microbial contributions to nutrient cycling.

This lecture explores the innovative use of Lab-on-a-Chip (LOC) technologies in conservation and environmental applications. LOC devices, which miniaturize laboratory processes onto a single chip, offer rapid, cost-effective, and portable solutions for monitoring ecosystems, and conserving biodiversity. The presentation will cover the integration of microfluidics, sensors, and bioanalysis for real-time environmental data collection, highlighting their potential in addressing global challenges. Case studies demonstrating the impact of LOC in wildlife conservation, and ecosystem monitoring will also be discussed.

Multiple traits, including antipredator responses, foraging behaviour, development rate and fecundity, contribute towards an organism's fitness. These diverse traits interact through the shared resources allocated to maximise fitness. Ecological conditions can affect these interactions by driving increased investment in a particular trait at the cost of other traits (inter-trait trade-off). How are these interactions affected when an individual goes through different development stages, which serve different functional roles? What are the consequences for an individual's fitness in such a complex life-cycle?
To understand the trade-offs that operate at multiple levels in a complex life cycle, I investigated the role of early predation risk conditions across the life cycle of the holometabolous insect– Aedes aegypti. Aedes aegypti has four major stages: egg, larva, pupa, and adult. Previous work suggests that ecological conditions experienced by the larval stage affect adult traits. However, we lack knowledge of how early larval conditions affect the pupal stage and the cumulative effects of both stages on adult traits.
To understand multistage, inter-trait trade-offs, I exposed the immature stages to a key selection pressure, predation risk. Leading to our aim of understanding the combined and individual roles of larval and pupal stages in managing trade-offs, I first unravelled the relationship between larval and pupal stages. I adopted behavioural approaches to examine (1) the carryover of larval predation-risk experience on the pupal stage to understand if a pupa independently responds to risk or whether the larval experience influences its response to risk conditions. I discovered that a pupa that has experienced predation risk as a larva modulates its response to predation cues, showing that the larval experience affects pupal traits. This experiment showed that a behaviour or experience with an adaptive value can overcome the barrier of metamorphosis. Since Aedes aegypti larvae and pupae are found in group settings, I also examined (2) the behavioural manifestation of predation experience in a group setting. This allowed me to understand the abilities of the pupal stage in responding to risk conditions under different contexts. I found that experience does not influence the behaviour of an individual pupa if it is in a group. This is probably because being in a group is an antipredator response itself. My first two chapters highlight the need to include the pupal stages in life history studies because of their ability to process different cues while responding to their environment.
After discovering the context-dependent antipredator response of the pupal stage, I examined (3) the multistage trade-offs, driven by early predation risk conditions, between larval-adult, pupal-adult and larval-pupal-adult stages. I performed lab-based controlled experiments where I followed all the life stages under risk and no-risk conditions. On analysing diverse morphological, biochemical and life-history traits of risk-experienced and naive individuals, I demonstrated that the fitness consequences differ for males and females, and it may start from larval-pupal trade-offs and accumulate as the risk persists. I also found that the pupal stage, like the larval stage, can respond to risk conditions both behaviourally and physiologically. However, it is less well-equipped than the larval stage to manage the trade-offs. Fitness consequences are worse when the pupal stage alone experiences risk. Hence, different stages can contribute to trade-offs that lead to various fitness consequences.
My thesis yields novel insights into life history evolution by displaying the ability of individual life stages to manage trade-offs. It highlights the importance of a poorly understood pupal stage, which can respond to different environmental cues, behaviourally and physiologically. It also explains how the abilities of individual stages to manage trade-offs independently and cumulatively can change the consequences for adult fitness.

Invasive alien species represent a significant global threat to ecosystems, economies, food security, and human health. They are responsible for 60% of global plant and animal extinctions. In 2019, the global economic cost of invasive species exceeded USD 423 billion annually, with costs increasing at least fourfold every decade since 1970. High-elevation ecosystems, however, remain among the few areas not yet heavily impacted by these species. This is expected to change as invasive species expand their range upwards to occupy new climatic niches in response to ongoing human-induced disturbances. The construction of infrastructure, such as roads and railways, is accelerating this process, particularly in the Kashmir Himalaya. Particularly, the roads act as effective corridors, facilitating the spread of invasive species along elevation gradients in mountain areas. In my presentation, I will discuss what we know about plant invasions in mountainous landscapes in general, with a particular focus on the Kashmir Himalaya.

My research explores the dynamic and multiscale nature of animal behavior, integrating insights across scales of biological organization. Today, I will discuss two key directions of my work.

Firstly, I will present past findings about how the brain makes decisions when faced with spatial choices. I will highlight the evolutionary universality of this algorithm and discuss the consequences this has for our understanding of movement and social influence in animal collectives. I will emphasize why explicit consideration of space is important for decision-making processes and extend these insights to ecologically and evolutionarily relevant contexts, specifically to the study of mate-choice on antelope leks.

Secondly, I will delve into a new research direction focusing on animal search behaviours, using prey search in octopus-fish hunting groups as a prime example. Contrary to traditional views, my field-based analysis reveals mutual benefits in these mixed-species relationships, with different species contributing to group movement decisions in distinct ways. By leveraging natural variations in group composition, I demonstrate measurable improvements in octopus foraging success within these mixed-species hunting groups.

Overall, my research underscores the importance of integrating insights across biological scales for a comprehensive understanding of animal behaviour and its ecological implications.

Social insects like ants, bees and wasps are well-studied for their efficient colony organization through division of labor, and their complex mode of communication, primarily mediated through chemical cues. Although the first social insect genome was sequenced nearly 20 years ago, it is only in recent years that neurogenetic tools have been developed to study the molecular and neural pathways underlying social behavior. I will use two social insect species- a tropical paper wasp and an army ant - to illustrate how the integration of behavior, genomics, and neuroscience can provide a holistic understanding of behavioral phenotypes and uncover novel mechanisms driving social behavior.

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.

Over the last decade, several studies have shown the importance of individual variation in natural populations. Theoretical ecological studies are beginning to incorporate trait variations in models, but they continue to be largely ignored in the context of ecosystems that exhibit alternative stable states. We study the role of trait variation in the context of a bistable ecological system, specifically a savanna-woodland system. In the first chapter, we begin with a mean-field model of bistable savanna-woodland system and then introduce trait variation in functional and demographic traits of savanna trees and saplings in the model. Our study reveals that higher trait variation reduces the extent of bistability in the system, such that the woodland state is favored; i.e. woodland occurs over a wider range of driver values in comparison to the grassland state. We also find that the shift from one state to another can become less or more drastic, depending on the trait which exhibits variation. Interestingly, we find that even if the overall tree and grass cover remain insensitive to different initial conditions, the steady-state population trait distribution can be sensitive to these conditions.

In the second chapter, we formulate a spatially explicit model of the savanna-woodland bistable system. Local interactions can vary with space, and can also change the stability landscape of dynamical systems. Fire events in savanna are also an important spatial process as they rely on the connectivity of fuel to spread in the system. Savannas also experience strong seasonality with a wet and dry season, fires being a prominent occurrence during the dry season. We incorporate these realistic features of fire and seasonality in our model along with two different demographic stages of savanna species. When comparing the spatial model to the mean-field approximation of the spatial model, we find that grassland state exists for a larger range of driver values, as short-range dispersal limits the spread of savanna species in the system. We find that fire leads to bistability in the system with grassland and woodlands as alternative stable states, while savanna state occurs as a transient state. We also find that irrespective of the initial flammable cover, the proportion burnt area depends on the flammable cover before the dry season, which depends on the wet season processes.

In the third chapter, we introduce trait variation in the spatial model to understand its role. We find that among all savanna species types, the fittest individual survives, while other types get eliminated from the population. The dynamics followed by the system with variation is same as the dynamics of a system with only the fittest individual.

Our findings suggest that individual variation in bistable ecological systems may have important consequences for both ecological and evolutionary dynamics and management practices.

Studying foraging behaviour unlocks access to the strategies used by organisms to optimize to the environment within the limits of constraints, and thus adapt to their environment. It uncovers information from an individual level to higher orders of organizations; how to optimally use the landscape and how energy flows across in its ecosystem. I intend to explore the foraging ecology of the tropical bat, Megaderma spasma from multiple perspectives; viz. the hunting behaviour, the energetics; and the encounter with its prominent prey species, Onomarchus uninonatus.

In my first chapter, I try to decode the animal behaviour from movement data, and characterise the bat hunting strategy. The high resolution data from bat-borne biologgers include IMU sensor, GPS and audio recorder. We intend to use the multimodality of the data to cross-check the behaviour signals across the data types. From the GPS data, I intend to understand the bat preference for forest patches.

In the second chapter, I explore the bat energy loss and gain in its active duration, and intend to put it in a theoretical perspective for better syntax to understand the energy efficiency for a bat. Understanding the bat strategies is our key to understand how evolution solved the problem of high energy demands. Instead of delving into the physiological aspect, I try to understand the bat foraging behaviour in the context of energetics, from the data collected from the biologgers.

In the third chapter, I aim to combine the database collected over the years about Megaderma spasma and Onomarchus uninonatus to computationally estimate the encounter rate in the wild.

Functional diversity estimated from species’ traits reflects their morphological, physiological, and ecological roles and their influence on ecosystem functioning and provides a link between species diversity and ecosystem processes. Understanding how functional diversity varies along environmental gradients can help us elucidate the species-trait-environment relationship and the underlying processes governing species communities. Richness-based measures, such as the number of species, have long been used to understand various aspects of global change, such as climate change, land use change, invasive species, etc. However, they do not provide much information about the consequences for ecosystem functioning. Functional trait-based approaches can offer insights into ecosystem functions and the structure of communities. I will use functional diversity and trait-based approaches to understand how ground-dwelling arthropod communities vary across environmental gradients. These ground-dwelling arthropods (ants, beetles, wasps, bees, spiders, ticks and mites, centipedes, collembolans, etc.) offer opportunities to understand biodiversity patterns on how communities can respond to environmental variation.
In the first chapter, I will study how the functional diversity of communities varies along an elevational gradient (from 3700 to 5000 m asl) in the Trans-Himalayas. Here, I will examine diversity patterns in multiple taxa along this gradient that interact with ground-dwelling arthropods (e.g., plants and soil microbial decomposers). In chapter two, I will focus on a subset of species that occur along the entire gradient, i.e., wide elevational distribution. Here, I will examine intraspecific trait variation in this subset of species to determine the characteristics of their trait-and-environment relationships. In chapter three, I will evaluate how invasive species can influence the functional diversity of communities across various land-use types. Here, I will study how Anoplolepis gracilepis (yellow crazy ant)—one of the 100 worst invasive species in the world—affects the community structure of ants. I will also test the trait-similarity hypothesis to ask whether the species that co-exist with the invader are functionally differentiated.
I expect this work will provide insights into how community structure and functions vary across environmental conditions.