I work on what can broadly be called "ecological and evolutionary energetics". The fundamental issue that I investigate is how energy use constrains and facilitates evolution and ecological processes, leading to multi-scale patterns in nature. I use both modeling and empirical approaches in my lab. I typically use protists when conducting lab-based experiments, although I have worked with birds, mammal, insects, bacteria, plants, and aquatic invertebrates too.
One of my most active areas of research is an effort to integrate classic ecological modeling approaches with macroecology. By using standard consumer-resource models, it is remarkably straightforward to make quantitative predictions about the scaling of population density and energy use with body size. This allows us to discover the mechanisms that generate large-scale patterns such as Kleiber’s law and the Energetic Equivalence Rule. Future work will attempt to unravel other patterns such as species-area curves and diversity gradients.
Another primary area of research is the evolution of body size. Although some studies show that observed body sizes can maximize fitness, the reason why individuals grow to the size they do is unknown. This is especially obvious when considering the many unexplained body-size “rules”, including Cope's, Bergmann's, the island, and the temperature-size rule. Using a new model of body size optimization, I am attempting to understand rapid evolution and phenotypic plasticity of body size with respect to climate change, population dynamics, and eco-evolutionary dynamics.
With a group of collaborators, I also have been attempting to understand the role of extra-metabolic energy use on the evolution of human life histories and the consequences for population growth. My work in this area has revealed new insights that should influence the way we think long-term about sustainability, including the strong dependence of economic growth on energy use, the inverted nature of the population dynamics of modern humans and the surprising assumptions of UN population projections, and on the rapid changes in human life history behavior with increasing energy use.