Researchers solve Darwinâ€™s copycat evolution puzzle
It is a clever trick if you can pull it off - mimic another, more
dangerous animal and so avoid being eaten.Many insects try it, but it
has been a long standing puzzle why some of the worst mimics in Nature
can still seem to escape becoming a meal.Now, Canadian scientists tell
Nature journal they can answer that one.Larger animals, they say, make
for more substantial meals, and so their mimicry needs to be spot on.
For small prey, a great performance is not so essential.
"Mimicry of harmless species pretending to be dangerous ones in order
to avoid being eaten is one of the best celebrated examples of the
outcome of evolution by natural selection," says Professor Tom Sherratt,
of Carleton University in Ottawa, who led the research."Good examples of
mimicry are highlighted in biology text books, but many mimics are poor
and their emergence remains something of a puzzle."Mimicry is common
among plants and animals.
Species of snakes, spiders and butterflies have all evolved to look
like other species to ward off predators. But one of the great mysteries
in biology is that most of this copy-cat behaviour is not very good, and
bad impersonators seem just as abundant as the good ones.A simplistic
interpretation of Darwin's theory of natural selection would suggest
that it would be better for all mimics to closely resemble the species
they are trying to impersonate.
One explanation for why some might not achieve this is the eye of the
This states that although the mimicking species aren't convincing to
humans, they do fool their predators whose senses are quite different to
Listen to the sound of a wasp followed by a hoverfly trying to sound
like a wasp.Darwinian selection would suggest that over time the
hoverflies that sounded most like wasps would be preferentially selected
until a species emerged that sounded very nearly, if not exactly, like
the creature it was trying to impersonate.
In contrast, the species that were poor mimics would all be eaten and
die out. The new Canadian research suggests why this hasn't
happened?Another theory is that poor mimics are an amalgamation of
unappetising species and so, although they don't resemble any one of
them to a predator, they do represent the worst possible combination.