Research Projects

Climate change is an emerging evolutionary force that is driving extinctions in some species while selecting for resilience in others. It is also reshaping species distribution and traits. The extent to which organisms are affected by global warming depends on the magnitude of environmental temperature increases and species-specific thermal tolerance limits. Among the most vulnerable to the pressures associated with climate change are ectotherms, as their physiology, behaviour, and survival are tightly coupled to environmental parameters such as temperature. While temperate regions are expected to experience greater absolute increases in temperature compared to the tropics, tropical ectotherms may be at greater risk. This is because tropical species have typically inhabited thermally stable environments over recent evolutionary time and therefore have evolved narrower thermal tolerance ranges They also operate close to their upper thermal limits, and as a result, even slight warming in tropical areas can lead to significant declines in organismal fitness and survival. We propose to study the climate vulnerability of Agamidae, which is an ecologically diverse family of lizards in India. Agamids present an ideal system to study the physiological and behavioural mechanisms that mediate resilience or susceptibility to climate change because they are widely distributed from arid landscapes and tropical forests to high-altitude rocky areas across India. However, little is known about their thermal biology, colour-mediated thermoregulation and photoregulation strategies, and physiological stress responses to temperature. We propose to characterise thermoregulatory traits and resilience capacity across evolutionary and ecological scales. This proposal is based on the hypothesis that agamid lizards exhibit multiple thermal strategies and adaptive traits (e.g., colour plasticity, heat stress responses, thermal and UV regulation) that mediate their capacity to cope with environmental warming, and that these traits vary across evolutionary (multi-species) and ecological gradients (habitats and altitudes). With India's rapidly changing climate and urban expansion, understanding these physiological thresholds and flexibility is critical for predicting the future distribution and persistence of these mesopredators. Understanding species' vulnerability to climate warming requires robust, mechanistic frameworks that integrate physiology, behaviour, and environmental data. By combining physiological measures of thermal tolerance, such as thermal preference (Tset) and critical thermal maxima (CTmax) and minima (CTmin), with ecologically meaningful measurements of environmental temperatures that animals are exposed to in their natural habitat (operative temperature, Te), we can estimate the thermal safety margin (TSM) and warming tolerance (WT) for individual species and populations. We will also measure the thermoregulatory and photoregulatory capacity of skin colouration in ultraviolet (UV), visible (VIS), and near infrared (NIR) spectra. And determine the physiological mediators of heat resilience, including heart rate, corticosterone, heat shock protein (HSP) expression, and heat hardening. These data are necessary to provide a predictive framework for assessing vulnerability under projected climate scenarios. Calculating metrics of vulnerability require on-ground measurements, which are simply lacking for much of the Global South, especially India. The mechanistic models proposed here, combined with measures of stress and adaptability (i.e. heat hardening) represent a valuable advancement in climate impact forecasting, particularly for ectotherms that actively thermoregulate in heterogeneous environments.