MY SCIENCE
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I am interested in understanding how the addition or loss of predators has ecological and evolutionary impacts on populations, communities, and ecosystems.
I do this by coupling ecological and evolutionary theory to management and conservation practice.
The three questions I am currently working on are:
the ecological consequences of the wolf reintroduction on the Yellowstone National Park ecosystem
the ecological and micro-evolutionary consequences of escaping predation for populations of guppies in the freshwater streams of Trinidad
the macro-evolutionary consequences of bird colonization on oceanic islands.
Why am I interested in these questions?
When many large carnivores were deliberately eradicated from Yellowstone National Park in the 1920s, all sorts of things in the park changed: elk numbers increased, bison struggled, and young trees of many species failed to establish. When wolves were reintroduced in the 1990s, and as bears and mountain lions naturally re-established in the park, things started to return to the way they were, but whether the park will ever look like it did in when Europeans first discovered it is yet to be seen. It may never recover to its previous state.
On longer time scales, changing predator numbers can lead to evolution of prey. When guppies live in the same stream as predatory fish within Northern Trinidad, they are rare, living at low density. They are also well-adapted to live with predators, having high metabolic rates and exhibiting behaviours that help them escape a grizzly end in the jaws of a larger fish. When these guppies are released from predation and moved to predator-free streams, they rapidly evolve, using existing genetic variation within their population, to live slower lives, lower their metabolic rates, and display behaviours associated with living in an environment where food is scarce and has to be strongly competed for.
Over even longer time periods when genetic mutations can accumulate, animals can evolve into new species when they escape from predation. The textbook example is the dodo of Mauritius. However, many bird species show similar, if not quite so pronounced, responses to the dodo when they establish on predator-free Oceanic islands and survive their for very many generations. Silvereyes, a study species my wife Sonya Clegg is the real expert on, which live on mainland Australia and on Islands of its Eastern coast, are a fabulous example of a bird that is starting to evolve some of attributes of the dodo on some of the islands it has colonised.
Conservation practice needs to incorporate evolutionary theory to account for adaption that occurs following ecological and environmenal change. We can use evolution to our advantage by harnassing its power when design management interventions.
My research is all about understanding why these ecological and evolutionary changes happen when predator numbers change, and what these changes might mean for ecosystems. I do this by developing theory that I can test with data collected from Yellowstone, Trinidad, and Oceania. However, I also work on several other systems, including some where changing apex predator numbers has little apparent impact on ecosystems.
Much of this work is currently funded by a grant from UKRI for £2M.
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