Passive Acoustic Monitoring (PAM) has emerged as a possible alternative to traditional field surveys, which are tedious, expensive, and often limited to a few sites. Although PAM eases collection of data, the sheer volume of data generated complicates the analysis process. Recently, researchers have simplified the analysis process by using soundscape-based machine learning models that can extract information such as species richness and occurrence from audio data. But most of these methods either fail to generalize to various landscapes and across anthropogenic gradients or have not been tested in such environments. Thus, for my first objective, I will develop soundscape-based methods to determine habitat quality across different tropical landscapes. I aim to collect audio data across different tropical habitats along a gradient of land use and test the performance of current soundscape-based models and build better generalizable models. Soundscape-based methods have also been able to track spatiotemporal avian biodiversity patterns in temperate climates at coarser timescales and infer species occurrence. Thus, for my second objective, I will test if we can use these methods to track avian spatiotemporal biodiversity patterns at finer timescales in tropical habitats, and if we can use soundscapes to predict presence of non-vocalizing species. I aim to collect fine scale audio data along with ground truthed bird species observations and test performance of these algorithms on the data. I also aim to build a model that can use soundscapes to predict the occurrence of non-vocalizing species. Studies have shown that insects are the most vocalizing species in tropical habitats, however, most studies don't focus on insect vocalizations. This can be attributed to the fact that building automated models for insect species identification using acoustic data is a challenging problem. Thus, for my third objective, I will use recent developments in the field of machine learning, such as transformers, to build acoustic identification models for insects and quantify insect biodiversity.

Coastal mangrove ecosystems remain among Earth’s most valuable forests, serving as key carbon sinks and protecting billions of dollars of coastal infrastructure from sea level rise. Mangroves are also highly vulnerable to both direct human influence and growing climatic threats, with hotspots of loss scattered across the tropics. This seminar will present the groundbreaking methodology and results from a global-scale satellite-based analysis to map the drivers and extent of mangrove losses over the last several decades. Using a machine learning analysis of over one million Landsat images, we capture mangrove losses due to agriculture, urbanization, sea level rise, and extreme weather events at high resolution. This analysis is currently being integrally used to monitor global restoration and conservation initiatives, inform key mangrove preservation policies, and evaluate progress on the Sustainable Development Goals.

This seminar will also provide participants with an overview of a large-scale capacity building initiative to train thousands of students across South Asia and West Africa with cutting-edge remote sensing tools for environmental monitoring. Participants will have the opportunity to directly get involved in training and collaboration opportunities with NASA, National Geographic, Google, and Stanford University in the field of satellite-based climate analysis.

Temperatures are rising and the thermal regimes of our ecosystems are changing rapidly, becoming warmer and more variable with more frequent extreme events. The impacts of these changes are the subject of much current research on a wide variety of organisms. Important questions revolve around what determines thermal tolerance or the thermal limits of a species distribution. Are they the same thing? And how best to measure or predict them? To assess the integrated response of organisms and communities to changing thermal regimes requires systems level perspectives that draw together impacts at different scales – e.g., cell vs organ vs organism within species; or plant vs pollinator vs pathogen at community scales. I will present work collaborators and I have been doing to better understand what thermal tolerance means, what drives it, and to explore how best to assess it.

Over 80 % of the world animals have complex life-cycles with multiple life-stages.  In many of these species, each life stage experiences dramatically different selection pressures, due to living in different environments and specialising in different tasks. For example, caterpillars must avoid predation while feeding on leaves, while butterflies must fly, find mates and feed on nectar. However, all butterflies were once caterpillars, and they share the exact same genome. This raises a fundamental evolutionary question – to what extent does the resetting of the body plan at metamorphosis allow for independent adaptation at each life stage? Answering this question is essential to predict how animals might adapt to environmental change. In this talk I will describe a recent collaboration looking at the evolution of colouration across life-stages of Australian Shield bugs, as well as future research plans to investigate the evolution of thermal tolerance in Australian leaf beetles.

Tropical forests are currently undergoing large-scale structural changes, including an increase in liana abundance and biomass. As critical but frequently overlooked components of these forests, lianas can reduce tree growth and increase tree mortality, thus significantly influencing the declining pantropical carbon sink potential. Despite the increasing importance of lianas, quantitative studies on liana abundance and their impact on forest carbon stocks are almost non-existent. Recent advancements in terrestrial laser scanning (TLS) technologies have provided a new lens through which we can examine forest structures. These developments facilitate observation on an unprecedented scale and offer improved accuracy. As a result, we can now reliably measure liana structure and assess its impact on the structure and functionality of tropical forests. In this presentation, I will elaborate on how the utilization of TLS, in conjunction with other recent technological innovations in the remote sensing field, has enhanced our ability to understand lianas. Additionally, I will share the insights we have gained about the role lianas play in contributing to the already declining pantropical carbon sink potential.  

Environments shape the development of physiology but also act as potent selective sieves to shape how physiological responses evolve. I’ll briefly discuss the work my group has been doing to 1) test how early thermal and resource environments shape thermal physiology in a model lizard system (Lampropholis delicata); 2) the generality of such findings across ectotherms and 3) some new work that explores the interplay between physiological plasticity and the opportunity for selection on physiological responses in an era of climate change. 

I will describe a few recent studies in our lab in Canberra. I will describe two fish studies on Gambusia holbrooki led by PhD students. One, by Ivan Vinogradov, is soon to be published work on the link between cognitive ability and fitness. The other study, by Meng-Han Joe Chung, is partly published work that teases apart the different costs of reproduction for males. I will then describe a recently published meta-analysis by a PhD student, Lauren Harrison, testing for sex differences in variation in personality. Finally, if time permits, I will briefly describe recent theoretical work I did with Lutz Fromhage (U Jyvaskyla, Finland) on how to measure inclusive fitness.

Foraging by animals is typically understood as a way to maximise food or energy intake. However, food is a complex mixture of multiple nutrients, each having specific functional implications for animals. The dietary choices of animals in the wild are influenced by both internal (such as, sex, physiological condition) and external factors (such as, predation risk, habitat heterogeneity, seasonal influence). Such environmental stressors can inflict stress responses in animals which in turn impose higher energy demands, leading to the rapid depletion of stored carbon-rich compounds. Their depletion requires replenishment by active foraging for carbon-rich food resources and thereby imposing new nutritional demands during physiological stress.  Seasonal breeding animals have different physiological demands across their seasonal regime based on their life history traits. While the stress hormone, that is corticosterone in birds and reptiles, is essential for survival during non-breeding stages, its over expression in the breeding stage could have potential negative impacts on their reproductive activities.   Using the sexually dimorphic tropical lizard species, Psammophilus dorsalis, as our model system, we studied the differences in physiological demands across seasons and their correlation with diet nutrient composition. We quantified stress levels and energy metabolite levels from blood samples and quantified the diet of adult lizards to prey Order level and determined the C:N ratios of their whole diet across seasons. I shall present our findings from this chapter during the talk and also give an overview of related studies that were conducted as part of my PhD. 

There is a high cost of not responding to the threat of predation; therefore, organisms have evolved different risk avoidance strategies. Animals use different cues (e.g., alarm calls, kairomones, refuge density) in their surroundings to save themselves from predators. They may also use past encounter experiences to improve their antipredator responses. Such carry-over effects can benefit the same individual or subsequent generations where animals occupy the same ecological niche. In a complex life cycle, every life stage differs morphologically, physiologically and functionally. These stages occupy different ecological niches and experience different selection landscapes. In such life cycles, every life stage is separated by a tissue remodelling event. Given these evolutionary and physiological constraints, do past predator encounters carry over to the next stage and influence its behavioural response? Or do they respond according to their immediate environment?   In the first chapter of my thesis, we answered these questions using a mosquito model system Aedes aegypti. Aedes aegypti has four major stages- egg, larva, pupa, and adult. We examined the effect of predation risk experience across larval and pupal stages. Larval and pupal stages differ in morphology, physiology and function but share the same habitat and, therefore, similar threats. We manipulated the threat of predation experienced by larvae and investigated its influence on pupal behaviour. I will present my findings during the talk and an overview of my PhD work progress. 

India is considered the world's snakebite capital, where over 58,000 snakebite fatalities are registered annually. Most bites are primarily attributed to four snake species: the spectacled cobra (Naja naja), common krait (Bungarus caeruleus), Russell's viper (Daboia russelii), and saw-scaled viper (Echis carinatus) that are collectively termed as the 'big four'. Recent research has unravelled a significant variation in snake venom composition and toxicity at inter- and intraspecific levels, resulting in an alarming ineffectiveness of antivenoms - the only available treatment for snakebites. However, the extent of venom variability, which often results from differing ecologies, evolutionary histories, and/or environmental conditions, remains largely uninvestigated in the majority of clinically important snakes. For example, the influence of varying ecology and environment on the venom of the common krait (B. caeruleus), the snake species with a near-pan-India distribution responsible for the second-highest number of snakebite-related deaths in India, has not been investigated to date. To address this knowledge gap, my PhD research focused on assessing the biogeographic venom variation in this species across India. Furthermore, I have evaluated the repercussion of this geographic venom variation on the preclinical efficacy of commercially available Indian antivenoms. Similarly, the extent of intrapopulation venom variation, especially at finer geographic scales, remains poorly understood. I had, therefore, employed an interdisciplinary approach involving venom proteomics, biochemistry, and pharmacology, to assess venom variation in monocled cobra (N. kaouthia) sampled across a small spatial scale ( <50 km). Finally, I have evaluated in vitro and in vivo venom binding and neutralisation capabilities of conventional antivenoms in countering toxicities inflicted by various individuals in this population. While conventional antivenoms have saved thousands of lives, they suffer from numerous flaws, such as ineffectiveness against necrotic effects, reduced dose-effectiveness that often leads to many secondary reactions, including fatal anaphylaxis, and unavailability in many primary health centres. Secondary metabolites of plants have been shown to effectively neutralise snakebite pathologies, especially the local effects such as haemorrhage and necrosis. Therefore, I have assessed the antivenomic potential of medicinal plants, such as avaram (Cassia auriculata), utilised in traditional medicine. The neutralising potency of Cassia auriculata flower extracts against medically important snake venoms has been evaluated using in vitro experiments. Finally, I identify the active components in these plant extracts and will explore their potential role in treating snakebites in India.