Ever since the satellite strategy was observed as an alternative reproductive tactic in males, various conditions have been manipulated to determine what affects the mating success of individuals using calling versus satellite strategies in crickets. These conditions include empirically manipulating densities of male crickets, and manipulating predation risk using simulations. We carried out experimental manipulations of predation risk to examine its effect on mating success in the tree cricket species Oecanthus henryi. Instead of treating reproductive strategies as categories, we considered propensity to communicate as a continuous trait. Since communication includes not just a distribution of calling effort in males, but also variable amount of searching by females, we addressed this question in both male and female crickets. Using field enclosure experiments, we tested whether increased predation risk affects mating success of male and female crickets via reduced survival or decreased propensity to communicate (ie. call or search). We increased predation risk faced by crickets inside enclosures and made behavioural observations using low and high resolution scan sampling. Whether mating success is dependent on male calling effort or survivorship was determined using a mixed model framework.

The engines of speciation have long been a matter of much debate. This talk will discuss the potential role of magic traits in assortative mating and disruptive selection leading to speciation in sympatry. It will provide a historical and contemporary view of the ideas and evidence for mechanisms that could result in sympatric speciation.

Please note that before the talk, there will be brief presentations on recent publications by Shruti Unnikrishnan, Sabiha Majumder, Pratibha Yadav and Sanjeeta Sharma Pokharel.

Introduction to library facilities for the newcomers

This thesis is spurred by the overarching question “why is a plant where it is in space and time?”, asked in the context of a tropical dry forest plant community in southern India, based on long-term research conducted in a large (0.5 km2) permanent sampling plot. We attempted to deconstruct the structure and dynamics of the plant community by first establishing the spatial structure of soils, topography and lithology in the plot. We then assessed how this spatial structure, together with temporal variation in precipitation, affected abundances of the eight most dominant species in the plot. Finally, we broke up abundance variation into the components of recruitment, mortality and stem radial growth and assessed how these respond to variation in environmental factors (precipitation, temperature, soils, topography and fire) and biotic neighborhoods.
Local-scale lithological variation was an important first-order control over soil variability at the hillslope scale in this tropical dry forest, by both direct influence on nutrient stocks and indirect influence via control of local relief. Species separated into two broad groups in niche space – one consisting of three canopy species and the other of a canopy species and four understory species – along axes that corresponded mainly to variation in soil P, Al and a topographic index of wetness. Our results suggest that this tropical dry forest community consists of several tree species with broadly overlapping niches, and where significant niche differences do exist, they are parsimoniously viewed as autecological differences between species that exist independently of interspecific interactions. Temporal environmental factors (time since last fire, precipitation, and minimum and maximum temperatures) appear to be the strongest drivers of dynamics in this community, followed by conspecific and heterospecific neighborhoods, followed by spatial environmental factors (soils and topography). It is hoped these results will provide information relevant to understanding, managing, and predicting the future of this ecosystem and contribute towards the development of general theories of plant community ecology.

Animal groups show striking patterns in their structure and movement. Sometimes, these patterns also have functional consequences, such as V formation in bird flocks aiding in group navigation efficiency. Emergent group behaviour is often not a direct sum of individual level behaviour, instead it is a consequence of interactions among individuals. Understanding such patterns at the group level might help us unravel individual response to changes in environment or disturbance. However, very few empirical studies have recorded such fine-scale interactions in the wild. One reason for the dearth of studies from the wild might be the difficulty in capturing multiple spatial interactions at a single time instant. Recent advancement in aerial imagery techniques allows us to observe and record such interactions.
We are studying spatial dynamics of Blackbuck (Antilope cervicapra) herds using high resolution aerial imagery . The data collection for the study was done at Blackbuck National Park, Gujarat, India. We have captured blackbuck herd movement and interactions in 15-min long videos.
Main objectives of our study are :
1. To examine the effect of habitat and inter-individual heterogeneity on group structure and movement dynamics
2. To understand leadership and merge-split dynamics in groups during external perturbations ( a proxy for understanding group dynamics in predation or threat scenarios)
We plan to understand group movement decisions by analysing data from these videos.

Sexual selection can favour the evolution and maintenance of highly elaborate traits in males. In many species, males show multiple morphological and behavioural-display traits. Though many studies have examined the role of sexual selection in shaping male display traits, they are typically done over a short part of the animal’s lifespan, and often in captive or semi-natural conditions. Patterns of variation in multiple display traits over the lifetime of individuals under natural ecological and social contexts are still not well understood. Apart from traits related to mate-acquisition, sexual selection can also influence behavioural traits involved in other aspects of an animal's ecology. Traits related to animal personality form one such set of traits. Research on consistent between-individual differences (called repeatability) in various behavioural traits related to personality is rapidly expanding. However, we know relatively little about patterns in repeatability in traits over a lifespan, especially in the wild, and the role of sexual selection processes in maintaining repeatability. With the motivation of studying sexual selection in the wild, I focus on examining the influence of sexual selection on male mating behaviour and personality in male Peninsular Rock Agama (*Psammophilus dorsalis*).

I first describe the natural history of the breeding system of this species. By following uniquely tagged individual lizards over their lifetime, I describe the breeding phenology and mating system of P. dorsalis. I then examine variation in multiple behavioural traits of breeding males and the influence of social context on these traits. My findings show that certain behavioural traits of displaying males show a strong pattern of covariation, are mostly directed towards females, and appear to carry predation costs. I also examine the relationship between these traits and indices of male mating success. To study the role of sexual selection in maintaining animal personality, I first quantified repeatability in risk-aversion behaviour. There is significant repeatability both in the short-term and over the lifespan of males. Finally, I examined the role of sexual selection by testing whether risk-responsiveness occurred in a behavioural syndrome with male display traits. However, I did not find evidence for the existence of a behavioural syndrome (i.e correlation) in personality traits measured across the contexts of mating and risk-aversion. Through such long-term behavioural monitoring of individual lizards, this thesis contributes towards a better understanding of the influence of sexual selection on multiple display traits, and on patterns in repeatability in display traits and risk-aversion, over the lifetime of an individual in the natural context.

The 19–49 My-old obligate mutualism between Macrotermitinae termites and the Termitomyces fungus is an example of an ancient agriculture system in which Termitomyces is cultivated by termites for nutrition. Termites, in
turn, keep other parasitic fungi like the parasitic weed Pseudoxylaria at bay. Unraveling the proximate mechanisms used in fungal cultivar protection is central to understanding the evolutionary stability of these farming mutualisms. We investigated the role of abiotic factors, antifungal chemicals and hygienic behaviours used by termites to keep their fungal gardens free from such parasitic fungi. Our results show the important role of abiotic factors such as termite mound temperature and CO2 in decreasing parasitic fungus growth. Using novel assays we also found that termites can display a differential behavioural response towards mutualistic and parasitic fungi and
that this behaviour is coupled with antifungal activity. These results not only shed new light on how the ecology of these fungi is affected by their host but also reveal the mechanistic basis that may contribute fundamentally to the evolutionary stability of this ancient mutualism.

Herbivore dung can be an important source of nutrients for soil. As most of the studies looking at the nutrient contribution from herbivore dung are based on agriculture with a focus on cattle dung, not much can be said about natural systems like tropical forests. In my thesis, I have looked at two aspects of herbivore dung decay: dung insect communities and dung-soil nutrient cycle. In order to understand the dynamics of the dung-soil nutrient cycle, we explored changes in dung nutrient composition above the soil and input of nutrients to the soil.

For my upcoming presentation, I will talk about second objective of my thesis, where I will be discussing transformation of dung above soil during the process of decay. Existing literature on biogeochemical changes during decay is limited to total carbon and total nitrogen. In this work, we have expanded existing knowledge with various important analyses: changes in carbon specific compounds such as lignin (recalcitrant component of dung) and sugar (easily decomposable), along with analytical pyrolysis to understand the overall changes. We explored the importance of initial nutrient composition in driving the rate of decomposition along with other factors such as seasonal changes and habitat type.

Observable patterns in nature, whether they concern morphological and molecular traits or range distributions, are caused by different processes. Through phylogenetics and post-tree analyses we can recover evolutionary trends and historical pathways along the history of organisms. In this talk, a few case studies from the evolution of flowering plants will be presented as means to understand character evolution and historical biogeography at broad and small scale.

Abstract: The relationship between regional climate and tree growth is not well understood in case of Himalayan conifers. In order to understand the response of trees to regional climate along an elevational gradient, tree ring chronologies of Abies pindrow are built at four elevational sites. The trees from different elevational sites respond differently to the local climatic variables. The positive correlation between growing season temperature and tree growth at low elevation site weakens with increasing elevation. The response to monthly precipitation also varies with increasing elevation. The response has changed in time as well in response to recent climate change. Also, different features of site chronologies like mean sensitivity, mean ring width, inter-series correlation etc. vary significantly with increasing elevation. This differential response of Abies pindrow to local climatic variables helps to understand the sensitivity of tree growth to climate at different elevations in a mountain system.