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Researchers break the animal kingdom's colour code
16 April 2009
York, University of
Charles Darwin was fascinated by the colours of animals - he once wrote to
his colleague Alfred Russell Wallace asking why certain animals were "so
beautifully and artistically coloured".
It is a question that has intrigued biologists ever since. Now research
spearheaded at the University of York (in collaboration with researchers
from the University of Glasgow, and Carleton University in Canada) has used
computer models to trace the evolution of this extravagant colouring.
Researchers in the York Centre for Complex Systems Analysis (YCCSA) sought
to explain why most animals that have an anti-predatory defence, such as a
sting or poison, tend to be brightly coloured.
Mimicry is common in nature. Defenceless species frequently evolve to look
like a nasty species, so that potential predators cannot distinguish between
the two -- a good meal or an unpleasant experience.
Such mimicry is good for the defenceless species which predators can mistake
for a daunting adversary, but is bad for nasty species which might be
mistaken as a good meal.
The YCSSA research, published in Evolution, suggests that nasty prey may
have evolved bright colours to avoid this kind of mimicry. Bright colours
are harder for defenceless prey to mimic because they have a survival cost
of increased detectability by predators. There are also many ways to look
distinctive when brightly coloured, but limited scope for doing so when
camouflaged, because camouflage needs to blend in with the background.
Lead researcher Dr Dan Franks, of YCCSA, said: "Our computer models show
that this way of looking at the evolution of bright colours explains why in
nature we generally find that the nastier the prey species (e.g. the more
poisonous) the brighter the animal.
"The nastier the animal, the more it can 'afford' a bright and distinctive
livery to copyright its appearance. It's similar to the way that big
companies closely guard their appearance in an attempt to build clear brand
recognition."
http://www3.interscience.wiley.com/journal/117958524/home