Intense competition among individuals of the same sex and species can result in striking, elaborate and costly traits. Such intrasexual competition has been widely studied among males; but it is only in the last few years that intrasexual competition among females has received attention. Recent reviews suggest that competition between females may be widespread; females may compete over a variety of resources including mates, food, nesting sites and safety; and such competition can have important behavioural and evolutionary consequences. However, systematic studies of intrasexual competition among females are scarce. Consequently, our understanding of the form that competition takes in females and the traits that evolve under such competition is limited. Owing to differences in life histories, the patterns and processes acting in female-female competition are expected to be different from those in males. In my thesis, I have focussed on studying traits and strategies in intrasexual competition in females in a polygynous species, the tropical rock agama (Psammophilus dorsalis), through observations and experiments in the wild.
The social system plays an important role in establishing the contexts in which various behaviours are played out. Establishing the social system of a population is essential for investigating the ecology and evolution of behavioural and life history traits. Thus, first, I studied the nature of between- and within- sex interactions across the lifetime of individuals in Peninsular rock agama using space use patterns. Individually tagged wild males and females were closely monitored and their home ranges estimated. Male home ranges overlapped multiple female home ranges, but females defended exclusive home ranges, suggesting strong competition.
I then examined signalling traits, which, observations on males suggest, play a key role in conveying information both in direct contest competition and in indirect competition to attract mates. I observed wild individuals every month across their lifetime to study the extent of female signalling and to understand the contexts in which the different signals are used. I also examined whether signalling rates are correlated with proxies of female fitness. I report that females, too, have a complex signalling repertoire. My findings suggest that females may signal both in direct competition in sexual and non-sexual context and to attract mates. Results also hinted towards correlation between signalling rates and some fitness proxies.
Finally, I examined strategies of female-female competition. Because of their investment in young, the costs of overt competition, such as conspicuous signalling and physical aggression, are expected to be comparatively high for females. Therefore, females should normally signal using relatively inconspicuous traits. They should be sensitive to the perceived threat, more so than males, and escalate to costly signalling and aggression only when the threat is high. I tested this hypothesis using field experiments and by simulating intruder threat on territories of wild female P. dorsalis. I report that in the normal signalling context, females signal using less conspicuous signals, less conspicuous than in males. I also show that females strikingly increase response in the form of signalling and aggression with increasing level of intruder threat. To summarise, I find substantial intrasexual competition in females of a polygynous species. Traits and strategies can be complex and different from that of males. Finally, owing to the cryptic nature of competition, an experimental approach might be key in studying competition between females.

India has among-st the highest burden of canine-mediated rabies in the world. India also has among-st the highest numbers of free-ranging dogs in the world, a lax dog ownership policy, and animal rights laws that conflate population management with rabies control. The failure to control rabies in India is a multi-faceted problem: a lack of systematic surveillance, limited knowledge on rabies dynamics in multi-host systems and poor implementation of mitigation measures. In this talk, I will explore the various facets of this problem, and show how a OneHealth approach that integrates Ecology allows for a better understanding of rabies dynamics in India and the development of targeted intervention techniques.

Himalayan gray langur is a little-known endangered primate, endemic to Himalayas. Its distribution and ecology are poorly known. In Kashmir and adjoining regions, it is likely at risk of extinction due to land use change and conflict with humans. In my thesis I assess the current distribution of this species in Kashmir and try to understand how this species copes up with seasonality in terms of food availability, quality and temperature differences.
In the first part of my thesis, we, aimed to ascertain the current distribution of this species in Kashmir and identify sites which face human-langur conflict. Using well-structured questionnaire and on-ground surveys we have attempted to determine the spatial distribution in Kashmir region. Results suggest Himalayan gray langurs to be distributed in two different habitat types dominated by broad-leaved deciduous forest and coniferous forests within an elevation range of 1700-3000 m. There was found little conflict in the area based on the questionnaire surveys conducted. Conservation education and awareness programs in schools and colleges were conducted throughout to impart knowledge about the existence of this primate species in their region.
Second part of my thesis involves understanding activity patterns and time budgeting in different seasons. Activity budget is an important component as it determines how animals interact with their environment by adopting various behavioural strategies to maximize energy and reproductive success. Various factors are known to effect activity patterns in primates such as food availability, quality, and temperature, etc. These factors influence the time allocation on different daily activities. Food availability is known to either increase or decrease the time primates spend on feeding and resting. In the case of Himalayan gray langur, it is expected to increase feeding time in winter when food available is scarce. Increasing time of feeding helps them thermoregulate in sub-zero temperatures. From the study, similar results on seasonal time budgeting were obtained. As far as daily activity budgeting was concerned, two feeding peaks during winter were observed, in the morning and evening. During summer, only one feeding peak was observed in the afternoon. This discordance may be explained by analyzing their diet and other environmental factors.

Thesis Colloquium

Male reproductive success can be driven by male mating effort in sexual signaling and in the benefits transferred to females during mating via nuptial gifts. Male mating effort, itself can be determined by various biotic and abiotic factors, such as nutrition quality, age, body size, mating status and temperature, contributing to the immediate condition of the male. In systems that involve long distance acoustic signaling by males for mate attraction, in addition to male mating effort, female motivation to acoustically localize a potential mate can also impact male reproductive success. Female motivation can again be governed by female condition. In my thesis, I studied the condition-dependent signaling and mating behaviour in an acoustically communicating tree cricket species, Oecanthus henryi. The first two chapters examine condition dependence of male mating effort in terms of male signaling and nuptial feeding respectively. In the second chapter, I also measured spermatophore attachment duration as a measure of male reproductive success. My results suggest that diet quality is an important factor in determining the male investment. Males reared on better quality adult diet had a higher lifetime and nightly signaling effort which would imply better mate attraction potential. In the mating behaviour, with increasing age males on high-quality diet had longer spermatophore attachment duration (SPAD) which can indicate higher sperm transfer and hence, higher fitness. Smaller males, received the least reproductive benefit in terms of SPAD across age and diet.
O. henryi males additionally exhibit a unique tool making behavior called baffling which increases their signal loudness. The gain in loudness is known to bestow a higher reproductive benefit (SPAD) to small males which are otherwise less preferred during mating. In the third chapter, we investigated the condition-dependence of this signaling strategy and found smaller males on better diet to have higher baffling probability. This result suggests that baffling is an energetically expensive alternate tactic used by the less preferred males possibly to improve their reproductive fitness.
In the final chapter of my thesis, I aimed to understand the effect of female dietary condition and mating status on female mate search and mating behaviour. Interestingly, female mating status and not diet turned out to be a key driving factor in this context. Despite a high remating propensity, mated females showed significantly low motivation to perform phonotaxis. Besides, both nuptial feeding duration and spermatophore attachment duration decreased in mated females. Thus, for a male it is more advantageous to mate with an unmated female. This highlights the importance of the proportion of virgin females in the wild population in relation to male reproductive success. Moreover, it could potentially determine sexual selection pressures in the system by introducing the additional competition in males for unmated females.

Tropical forests may be particularly vulnerable to extreme climatic conditions. These forests contribute disproportionately to global ecosystem services, and have dominant effects on global land-atmosphere interactions. Thus, understanding the responses of tropical forests to extreme temperatures and drought remain a major limitation in predicting global vegetation responses to future climate change. Work in my group examines how integration of anatomical, morphological and physiological traits translate to plant performance in changing environmental conditions particularly when experiencing extreme temperature and drought. Can this understanding help predict behaviour of tropical trees in the field; growth, mortality and regeneration over longer time scales; and ultimately, to distribution of species over environmental gradients, and responses of tropical forests to global warming? I highlight this work with two studies. The first, investigated the upper temperature limits of photosynthetic function. We asked how high temperature tolerance was related to morphological and physiological traits, and examined the consequences of this in the context of global warming. Our results show that tropical trees are precariously close to their upper thermal limits, and likely going to be severely affected by future warming. Importantly, thermotolerance differed between species and was related to leaf functional traits and photosynthetic rates. In the second study, we investigated water-use strategies in tropical trees, examining water uptake under well watered condition, and drought tolerance when water was limited. We asked if water uptake and drought tolerance were related to stem xylem anatomical traits, and tested the relationship between water transport efficiency and safety. Xylem size was positively related to water uptake, but negatively related to drought tolerance, resulting in a tradeoff where water uptake and growth under well watered conditions was negatively related to drought tolerance when water was limiting. These results suggest that tropical trees with acquisitive resource use strategies may be more negatively affected by increased temperatures and drought, and future climates may favour slower growing species with conservative resource use strategies.

Spiders, one of the top invertebrate predators in the terrestrial ecosystems are an ideal system to study ecological patterns and processes. Their hidden, but fascinating lives is full of drama: they are voracious predators, but get eaten by their own kind; they are also masters of trickery. In this talk, I will narrate two spider stories. One is of deception in the spider world: how ant mimicking spiders doubly deceive both visual predators such as jumping spiders and chemical predators such as mud-dauber wasps. Second story is about cooperation in hunting and web-building in social spiders. I will specifically talk about some recent work on how group size and hunger can influence the web architecture of social spiders.

Animal groups exhibit many emergent properties that are a consequence of local interactions. Linking individual-level behaviour to group-level dynamics has been a question of fundamental interest from both biological and mathematical perspectives. However, most empirical studies have focussed on average behaviours ignoring stochasticity at the level of individuals. On the other hand conclusions from theoretical models are often derived in the limit of infinite systems, in turn neglecting stochastic effects due to finite group sizes. In our study, we use a stochastic framework that accounts for intrinsic-noise in collective dynamics arising due to (a) inherently probabilistic interactions and (b) finite number of group members. We derive equations of group dynamics starting from individual-level probabilistic rules as well as from real data.

First, using the chemical Langevin method, we analytically derive models (stochastic differential equations) for group dynamics for a variable m that describes the order/consensus within a group. We assume that organisms stochastically interact and choose between two/four directions. We find that simple pairwise interactions between individuals lead to intrinsic-noise that depends on the current state of the system (i.e. a multiplicative or state dependent noise). Surprisingly, this noise creates a new ordered state that is absent in the deterministic analogue.

Next, we develop a method to derive the group-level dynamical equation directly from the data of collective dynamics. We assert that such an equation extracted from the data encodes important information about the underlying interactions. Therefore, we derive this equation describing the dynamics of order in two real systems- Fish (Etroplus suratensis) and Whirligig Beetles (Gyrinidae dineutes) in my next two chapters.

Focussing on small-to-intermediate sized groups (10-100), we demonstrate that intrinsic-noise induces schooling (polarized or highly coherent motion) in fish groups. The fewer the fish, the greater the intrinsic-noise and therefore the likelihood of alignment. Such empirical evidence is rare, and tightly constrains the possible underlying interactions between fish. Our model simulations indicate that E. suratensis align with each other one at a time (positive-pairwise), ruling out other complex interactions.

Finally, we apply the same method to swarms of Whirligig Beetles which shows contrasting rotational order. We find that a different set of interactions - negative-pairwise and positive-three-body interactions between individuals are required to explain the observed group dynamics. Whilst the three-body interactions can explain the structure of the deterministic part of the equation, negative-pairwise explains the stochastic counterpart.

Broadly, our results demonstrate that rather than simply obscuring otherwise deterministic dynamics, intrinsic-noise is fundamental to the characterisation of emergent collective behaviours, suggesting a need to re-appraise aspects of both collective motion and behavioural inference.

Animals across taxa and habitats are known to use available space non-randomly. They are known to concentrate their space use around locations rich in food, mates or refuges. There could also be cascading effects of such disproportionate use for the individual itself, its conspecifics or even the landscape it inhabits. In addition to using their habitats non-randomly for foraging, avoiding predators and optimizing homing routes; some social insects were also discovered to use their nest space non-randomly. We tested if the primitively eusocial paper wasp Ropalidia marginata used its nest space non-randomly and indeed found a majority of individuals using parts of the nest more intensively than expected by chance (spatial fidelity). We tested several hypotheses that were primarily based on studies on ants, to understand the relationship between the social and spatial organization of individuals in social insect colonies. We found that the non-random space use by adults within R. marginata nests is a result of maximizing nutritional exchange and minimizing disease spread in the densely populated colonies. In addition, in order to understand the role of non-random space use by adults on task performance, we tracked individuals while they performed the task of food distribution, as it is the most conspicuous and important task in social insect colonies. We found that wasps within a feeding bout cooperatively (and often repeatedly) fed the randomly distributed larvae, thus minimizing the chances of any larvae going hungry. Each wasp that fed larvae in a feeding bout optimized its feeding route by minimizing the distance per unit larvae it fed. We conclude that understanding the spatial organization of adults might help us better understand the mechanism of efficient division of labour on social insect nests.

The evolution of flamboyant traits in animals is typically attributed to the selective force of sexual selection. However, natural selection can constrain the degree of elaboration of such traits. Therefore, animal signals reflect a balance between natural and sexual selection. I examined the role of these forces in the maintenance of a complex visual signal: dynamic colour change. Males of the Indian rock agama (*Psammophilus dorsalis*) exhibit rapid dynamic colour changes on their dorsal and lateral body regions during social interactions. The costs, benefits and adaptive significance of this relatively rare signal type is yet unknown.

Using a combination of visual modelling and field experiments, I first examined the predation risk on social colours and found that the courtship signal of males is costlier than the aggression signal. I then tested whether male colours expressed during aggression convey information about individual physiology and performance measures. Apart from a negative association between testosterone levels and the yellow colour expressed during aggression, body size and bite force were correlated, suggesting that body size could be an honest predictor of fighting ability. In the third chapter, I examined differences in health parameters of males and females that occupy dramatically different habitats as a consequence of urbanization. Our results suggest that lizards in urban areas appear to have shifted their innate physiology in order to cope with urban stressors. Finally, I examined the response of receivers to different components of the male colour signals by assessing attention paid by conspecific receivers to each signal component independently and together. Both males and females responded equally to all male social colours although females showed difference in response to achromatic signals. Overall, we conclude that dynamic colour change may have evolved in this species to actively balance the costs of predation risk with the benefits of social signalling.