Predators matter for ecosystems in all sorts of ways. The exclusion of dingoes south of Australia’s 5600km dingo fence has caused sharp spikes in macropod populations, poor vegetative growth and declines in soil quality. Trophic cascades like this occur in terrestrial, marine, and freshwater systems, but are not universal. For example, lions do not play an important role in the dynamics of the Serengeti: change the size of their population and there is no discernable impact on the numbers of wildebeest or zebra upon which they predominantly feed. When trophic cascades do occur, they can result in evolution as well as ecological change. Guppies rapidly adapt to predator-free environments via the rearrangement of genetic variation already within their populations, while over longer time periods, new species evolve as genetic mutations occur. When pigeons establish on predator-free oceanic islands they repeatedly evolve into species like the dodo and Rodrigues solitaire, conforming to a pattern known as the island rule where small animals tend to get larger and slow down their life histories, while larger animals do the opposite. Yet many organisms, including most amphibians and reptiles do not exhibit rapid evolution or the island rule when their predator populations are impact. My research agenda focuses on understanding what happens when predator numbers change in ecosystems. My team and I research this question using a mix of observational fieldwork, experimentation, and mathematical modelling. Current study systems include Yellowstone National Park, the Northern Range of Trinidad, and mainland Australia and oceanic islands of its East coast.
Experience & Qualifications
PhD in Biology, Imperial College
Professor at Imperial College and then Oxford for last 15 years.