An important area of interest in behavioural ecology is to understand the large variation in traits related to reproduction and one explanation is that this variation is adaptive and is shaped by natural selection. In wild populations, multiple selection pressures are likely to simultaneously shape trait evolution. While these multiple selection pressures can manifest through different ecological or demographic conditions, these conditions themselves could vary predictably over space or time, or in an unpredictable manner, a relatively less studied form of environmental variability.

In my thesis, I attempt to understand how oviposition site selection, a behaviour where multiple selection pressure regimes are rarely considered, is shaped by multiple factors in a variable environment. Using *Aedes aegypti* as a model system, I first measured fitness trade-offs associated with larval predation risk and conspecific competition risk at potential oviposition sites through experimental manipulation in the laboratory. I also quantified spatial and temporal variation in two risk factors, pool desiccation risk and larval predation risk, through an observational study under natural conditions. Considering these trade-offs, I predicted and tested female oviposition site selection response to these varying multiple risk factors in the field. My findings indicate that oviposition site selection responses are complex, sensitive to interactions between multiple risk factors and influenced by patterns in variability in some of these factors.

Division of labour plays a very important role in social insects and could
either be reproductive or non-reproductive in nature. The lack of
morphological differences among individuals in primitively eusocial species
lead to greater flexibility in their social roles making them very
interesting model systems to study division of labour. *Ropalidia
cyathiformis*, a primitively eusocial wasp was chosen as the model system
for the study of reproductive and non-reproductive division of labour. One
of the key findings reveals that while dominance behaviour is used as a
mechanism for reproductive division of labour, age is used for
non-reproductive division of labour. We also compared our findings with
what is already known in a related conspecific, *Ropalidia marginata*. Our
findings showed that *R. cyathiformis* maybe a more primitive species
compared to *R. marginata* and provide a glimpse into the origin of
eusocial insects.

Many organisms (including humans) depend on sound for communication, predator/prey detection, and navigation. Thus, the intrusion of anthropogenic noise has consequences, masking natural sounds, altering wildlife behavior, physiology, and distribution and increasing stress and annoyance in humans. My research focuses on the science of sound in a landscape, examining the distribution and impact of noise pollution and monitoring biodiversity using acoustic recordings. Using thousands of hours of acoustic recordings and continental-scale sound models I examined the level and drivers of noise in U.S. protected areas. I found that noise pollution was pervasive, doubling background sound levels in 63% of U.S. protected area units and causing a ten-fold or greater increase in 21%, surpassing levels known to interfere with human visitor experience and disrupt wildlife. The dominant noise sources were aircraft and automobiles, while the loudest noises were emitted from trains and watercraft. Using a spatial planning approach, I am working to combine this information to build a framework for a national noise mitigation strategy. Extracting meaningful biological information from large-scale acoustic recordings can be problematic given the volume of data, with many approaches being prohibitively labor intensive and time consuming. Thus, I test the utility of bioacoustics indices, which are increasingly used to rapidly characterize biological communities. I reviewed the acoustic index literature, analyzing the efficacy of different indices to characterize bioacoustic activity, species richness, functional diversity, and landscape attributes. I then implemented a subset of the most effective indices on acoustic data collected at over 50 sites in both terrestrial and aquatic habitats across the continental U.S. I found that bioacoustics indices reflect the richness of species vocalizing in acoustic recordings and the abundance of common avian species song. Thus, bioacoustics indices and large-scale recordings offer a powerful tool, with the potential to monitor the dynamics of biodiversity and ecological communities across enormous spatial-temporal scales.

The Western Ghats is a biodiversity hotspot extending along the west coast
of India. It has a high endemism and harbours over 5000 plant species.
Whereas, the evergreen forests populating the wet zone on the western
slopes have existed since 65 million years ago, the deciduous forests
populating the eastern plateau were established during the Miocene
aridification about 10 million years ago. Additionally, the wet zone also
has a latitudinal gradient in length of dry period that was established
after the intensification of the monsoons and thus affects species
composition, with the relict evergreen species largely confined to the
southern refuge pocket. In this study, we tested the antiquity of the
evergreen forests, the southern refuge hypothesis, and the relationship of
species across these forest types.

We found evergreen forests show antiquity compared to deciduous forests,
and PD patterns corroborates the southern refuge hypothesis. Most
interestingly, deciduous forest species show shared evolutionary histories
with evergreen forest species, suggesting shifts in this trait, whereas
evergreen forests show greater disparate histories possibly due to their
antiquity and sharper gradients in the wet zone.

In many cooperatively breeding vertebrates and primitively eusocial insects individuals choose to remain as helpers throughout their lives despite being capable of independent reproduction. An interesting question that arises is whether such a helping role makes these individuals become reproductively constrained due to ageing and/or helping behaviour (thus are left with the only option of procuring indirect fitness benefits) or whether they can revert back to direct reproduction (and thus gain direct fitness in the future). Here we investigated the effect of age and tasks performed by helpers in the primitively eusocial wasp Ropalidia marginata on their ability for future independent reproduction, by isolating every wasp in the colony and giving them equal opportunity to initiate their own nests and lay eggs. We found that wasps which initiated nests and laid eggs were significantly younger and fed more frequently as adults than wasps which did not initiate nests. However, we did not find any significant influence of the tasks performed by the wasps on their ability to initiate nests and lay eggs. We conclude that ageing and receiving less nutrition rather than working for their colonies, constrain individuals of this wasp species for future independent reproduction. Because future direct fitness and present work towards gaining indirect fitness are not incompatible, we expect to find that although wasps may attempt to gain opportunities for direct reproduction as early as possible, they are nevertheless likely to keep working for the colony until they succeed.

Species diversity shows not only spatial, but also temporal patterns of change. The fossil record retains information of change in communities of species over millions to over thousands of years. Examining such fossil deposits allows for detailed understanding of how individual species and communities of interacting species may have changed over time. This also facilitates our ability to forecast and predict changes in response to future climate change. Fossil deposits, especially those spanning the Pleistocene, are rare in the Indian subcontinent. Using one such small mammal paleo-deposit from the Pleistocene-Holocene from Andhra Pradesh, I will provide a brief introduction to the field of, and the methods in paleo-ecology and what we can learn from looking into the past. I will also discuss the limitations of such datasets, especially from the tropics where degradation is rapid. Despite this, this approach can yield very interesting insights into community responses to long-term ecological and climatic changes.

Participation by Registration only

Recommended for people with experience in generalised linear models. Participation by Registration only

Recommended for people with experience in linear models (e.g., regression, ANOVA). Participation by Registration only.