Evolution in Color: From Peppered Moths to Walking Sticks

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The color of an animal can determine whether it lives or dies. If it’s easily spotted by predators, it may well become a meal. Hidden nicely against its background, an animal can escape its enemies for another day.

The particular colors on an animals are determined partly by the genes its gets from its parents. That means that genes that hide animals can spread thanks to natural selection, leading to the evolution of exquisite camouflage. But that’s not to say that the animal kingdom has settled on a perfect, fixed palette. You can find mismatched individuals. Over the course of generations, a whole population can flicker between mismatched and well-matched.

The most famous example of mismatched colors first came to light in the 1950s. Coal smoke had darkened England’s trees, so that light pepper moths, once blended nicely against bark, now stood out against the smudgy background. A dark form of peppered moths, once rare, became common. Researchers suspected that natural selection was the reason why, and they tested that idea by putting dark and light moth models on trees. Birds quickly attacked the mismatched ones, as had been predicted.

The photos from these experiments became a staple of textbooks. But doubts arose about the research. Real peppered moths often don’t sit on tree trunks with wings extended, for example. Creationists called the whole phenomenon a fraud and a reason to question evolution itself.

Written By: Carl Zimmer
continue to source article at phenomena.nationalgeographic.com

9 COMMENTS

  1. I was there, in London, in the 1950s. Peppered moths on elm trees. I didn’t realise then, but I do now. In London we had the disgusting thick “smogs”, smoke/fog, created by filthy burning of coal. I used to collect butterflies/moths and with some friends noticed that the moths on the elm trees were getting harder to find/spot. They were adapting to their environment, changing to evade predators.

    Amazing!

    • In reply to #2 by ArloNo:

      I was there, in London, in the 1950s. Peppered moths on elm trees. I didn’t realise then, but I do now. In London we had the disgusting thick “smogs”, smoke/fog, created by filthy burning of coal. I used to collect butterflies/moths and with some friends noticed that the moths on the elm trees were…

      They also had lots of Elm trees – prior to the importation of Dutch Elm disease!

  2. Convincing and fascinating; not only the walking Sticks but the entire invertebrate ecosystem of the bushes subject to attack from birds. Collateral damage resulting in benefit for the plant!

  3. The interesting side effects of concentrating birds on sites of recognisable abundant (stick-insect) food protecting the bushes! Ecology in action!

    @Roedy – Look at the picture. It is is not just colour, it is pattern. The insects mimic the leaf veins.

    There is quite a diversity of forms of mimicry from sticks to whole leaves.

    http://en.wikipedia.org/wiki/Phasmatodea

    http://animals.nationalgeographic.com/animals/bugs/stick-insect/

  4. I absolutely love walking sticks and insects that look as if they are leaves. If you google “insects that look like leaves,” the images are incredible. I find it amazing that some look like brown leaves, while others are green with “decayed” yellow/brown edges. I admit that these bugs with their fascinating twig-like joints and “leaf” veined wings keep me enchanted.

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