Professor of Zoology
University of Oxford
We hear a lot about the horrors of climate change, but it is not humanity’s only catastrophic impact on the natural world. Apex predators are in decline across much of the globe due to a process called trophic downgrading and this is altering ecosystems from the African savanna to the deep ocean floor. In addition, smaller predators such as cats and foxes have caused major population decline and extinctions when introduced into ecosystems in New Zealand, Australia, and oceanic islands. Yet under some circumstances altering predator densities has mimical impacts on ecosystems. My research interests focus on when, how, and why, altering predator numbers can have substantial impacts on natural ecosystems.
I address this question by developing mathematical models that we parameterise with data from field studies and subsequently analyse to identify general patterns. The three systems I work with most are i) the Yellowstone ecosystem where the loss, and subsequently re-establishment, of wolves and mountain lions has had significant impacts on many populations including of elk, bison, aspen, and cottonwood, ii) the freshwater streams of Trinidad where the presence or absence of predators influences microevolution of their guppy prey, community structure, ecosystem fluxes, and eco-evolutionary feedbacks., and iii) the silvereyes of Oceania that repeatedly evolve island forms when they escape from predation on mainland Australia and establish on oceanic island in the Pacific.
When I am not in the field I am based at the University of Oxford where I am Professor of Zoology. Annoyingly, I am also joint head of the newly formed Biology department. I am due to be released from this sentence in October 2024 at which point I intend to have a massive party. My favourite joke has the punchline “I thought it was frost on your moustache”.
- The phenotypic, life history and population dynamics of Yellowstone wolves. Along with Sarah Cubaynes and Jack Massey I have recently been collaborating with Doug Smith, Dan MacNulty and Dan Stahler of the Yellowstone wolf project. We have been conducting statistical analysis and constructing and analyzing models to investigate how hunting, disease and climate change might impact both wolves and the wider Yellowstone ecosystem. The reintroduction of wolves to Yellowstone provides a wonderful example of an ecosystem cascade. It is a joy to try to model this system.
- The role of predation and interspecific competition on the eco-evolutionary dynamics of Trinidadian guppies. David Reznick’s guppy system is the post-child for rapid evolution. The guppy system is remarkable because evolution is repeatable, and guppies can be studied in the wild, in semi-natural mesocosms and in the lab. It is one of the few natural systems I am aware of where observation, field and laboratory experimental can be combined. I have recently started modeling the eco-evolutionary dynamics of this system with David, Andres Lopez-Sepulcre, Joe Travis and Ron Bassar.
- The development and application of structured models to address questions in comparative demography. Jean-Michel Gaillard is another long-term collaborator. Jean-Michel, Tulja and I have conducted various comparative demographic analyses over the past few years, and we continue to look for general cross species patterns in life history and population dynamics.
- The population, quantitative genetic and life history dynamics of silvereyes. I have recently begun collaborating with Sonya Clegg. Sonya now runs the silvereye study started by Jiro Kikkawa in 1968. The detailed individual life history data are ideal to understand how environmental change influences body size and beak morphology of silvereyes on Heron Island, Queensland.