Biophysical ecology of the white-footed sportive lemur (Lepilemur leucopus) in southern Madagascar

Abstract

Understanding the impacts of environmental change on wildlife will require an integrated approach that draws together different disciplines and exploits new technologies and innovations. Biophysical mechanistic models have emerged as key tools for trait-based species conservation management and risk assessment. Mechanistic models apply fundamental principles to predict animals' energetic requirements and provide insights into underlying drivers of distribution change and species vulnerability to future climate change. Madagascar supports 23% of the world's primate diversity, however all species are at risk from a range of threats, including anthropogenic climate change. Biophysical models may provide important insights into the ecology of lemurs and other primates and assist in conservation. In this thesis, I used an interdisciplinary approach to examine the environmental limitations on primate fitness and distribution, focusing on the threatened primate: the white-footed sportive lemur (Lepilemur leucopus) of southern Madagascar. I undertook both experimental and field-based studies and developed a biophysical mechanistic model of Lepilemur to demonstrate the utility of the biophysical approach for informing conservation of a threatened species. I commenced with a literature review of the role of plant toxins in influencing herbivorous primate feeding behaviour. Unlike in other plant-herbivore systems, I did not find clear links between plant toxins and primate feeding ecology. This is likely due to the varied field methodologies and measures of plant quality and the tendency for primate studies to overlook interactions between nutrients and toxins. An understanding of regional climate variation and long-term change is dependent on high-quality and high-resolution spatial data layers. I developed a new method of anomaly interpolation to improve on the spatial consistency of spatial climate data in Madagascar for ecological modelling and to examine long-term patterns in regional climate change. The study revealed larger increases in temperature than has previously been identified, particularly in south of Madagascar. I then undertook an intensive field study to examine the environmental drivers of the energetics, physiology and behaviour of free-living L. leucopus, which included measuring field metabolic rate and water turnover using doubly-labelled water. The study provided evidence to reject the dominant energy-saving hypothesis and instead suggest that L. leucopus has elevated thermogenic capacity for cold defence. Within-season climatic variations were linked to energetic outcomes and behaviour which suggests that the species is limited by both heat dissipation and resource limitations. The following two chapters were concerned with the energetic model. First, I developed a mechanistic model of Lepilemur in an online interactive framework from the empirical study that predicts energetic and water balance outcomes under controlled conditions. Second, I applied the mechanistic approach to predict the energetic outcomes of free-living L. leucopus and developed a spatial metric to map the risk of extinction under simulations of climate change. The models demonstrate that small changes in biology and environment can lead to population-wide consequences and higher risks of extinction. The online interactive format was an ideal application for the mechanistic models as it allowed for effective communication and engagement with the analysis and predicted outcomes. Show more