Imperial College London

Dr Samraat Pawar

Faculty of Natural SciencesDepartment of Life Sciences (Silwood Park)

Reader in Theoretical Ecology



+44 (0)20 7594 2213s.pawar CV




2.4KennedySilwood Park




Research themes


All organisms live with two major constraints: their body size, and their body temperature. Both factors govern rates at which individuals gather and use energy (metabolic rate) and thus ultimately, population dynamics and evolutionary fitness. The effects of size and temperature are intimately related. Size influences an individual's ability to maintain stable metabolic temperature (thermoregulate). Temperature in turn, especially in ectotherms, elevates metabolic rate, which scales with body sizeWe study how body size and temperature together drive interactions between individuals, and what combinations of size and ecophysiological strategies can be successful in different environments. Interactions are important in this context because organismal fitness in the field is determined by consumers exploiting resources (e.g., predators and their prey), mutualists exchanging services (e.g., plants and their pollinators) and competition (e.g., interference among individuals while seeking food).


Scores of competitive, mutualistic, and consumer-resource interactions between organisms form the fabric  of every ecosystem. Altogether, these interactions form large, complex networks that show interesting and sometimes unpredictable dynamics. Indeed, understanding how these complex systems arise and persist, and how they influence the fate of animals and plants embedded in them, is a fundamental problem that has occupied biologists for almost two centuries (e.g., see Darwin's gedankenexperiment about indirect interactions). We study how interaction network structure affects populations, and how community-level network structure in turn emerges from assembly of interacting pairs of populations. To quantify interactions, we use metabolic principles about effects of size- and temperature-mediated constraints on individuals.


All organisms live in an environment that varies thermally in space and time, ecologists have always sensed that climate plays a central role in driving ecological and evolutionary dynamics. For example, in the Origin of Species (1859), Darwin emphasizes that climatic fluctuations can interfere with natural selection by imposing physiological stress and destabilizing species interactions. An then, there is the small matter of unprecendented global climatic changes in climate (especially in temperature) currently taking place due to human activities. Building on our work on metabolism and biomechanics underlying species interactions, we study how short-term fluctuations as well as long term directional changes in environmental temperature affect biological systems, from individuals, interactions between individuals, to whole ecosystems.