Max Planck Research Group Predators and Toxic Prey

Chemically defended organisms communicate their unprofitability to potential predators with conspicuous warning signals – aposematism. A profitability spectrum among chemically defended organisms may be important in shaping ecological communities and interactions among species. For example, variability in chemical defences can switch the evolutionary dynamics of signalling systems from mutualistic to parasitic, and from visual signal monomorphism to signal diversity. But what constitutes unprofitability, and how important is it in shaping interactions among species? In the predators and prey research group we investigate these questions using a combination of laboratory experiments and field studies.

A mantid attacking and eating a chemically defended heliconian butterfly.
Chaval Brasil flickr

Project 1: The profitability spectrum of aposematism

Milkweed bugs are an excellent system for testing the economics of aposematic traits.
MrClean1982 flickr

There is a growing body of theoretical and empirical evidence that warning colours can be related in some way to the defence that they advertise. We are researching the link between warning colours and chemical defences, and investigating how prey optimise their aposematic defences. When should prey invest in only a single defence, and in what circumstances should they spread their investment across more than one defence?

Project 2: Ecological pharmacodynamics

The standard black box approach to predator physiology cannot shed light on the mechanisms by which the chemical defences of prey have their effect. Opening the black box is vital if we want to understand (i) the processes that have selected for critical sensory abilities in consumers, and (ii) how chemical defences change organism behaviour and physiology. We are researching the effects of consuming chemically defended prey on the behaviour and physiology of consumers. This gives us the opportunity to research adaptive evolution at the molecular and phenotypic level, and to explore the evolutionary ecology of variable defences.

Blue jays eating monarch butterflies are a classic example of the costs to predators of eating chemically defended prey.
Lincoln Brower, Scientific American 1969
Blue tits need to find as many as 1000 caterpillars a day to feed their brood of nestlings.
g3rb& flickr

At the University of Cambridge’s Madingley Wood, a site of special scientific interest (SSSI), we research the behavior of free-living avian predators. We fit blue tits (Cyanistes caeruleus) and great tits (Parus major) with passive integrated transponder (PIT) tags. These PIT tags trigger recording devices attached to feeders and artificial prey that we place throughout the woodland. With Liisa Hamäläinen (University of Cambridge) and Rose Thorogood (University of Helsinki) we are recording the attack decisions of hundreds of predators to determine how wild birds learn about chemically defended prey. 

From left: Dr Chris Thorne, Dr Gabrielle Davidson, Dr Hannah Rowland, Dr Caroline Brighton, Dr Tony Fulford