Tuesday, 29 May 2012


After catching a nice mimetic moth, I caught the classic example of a cryptic moth - Peppered Moth (Biston betularia).

It wouldn't sit still unfortunately but you get the idea. Against the right background, this almost disappears. Notice how the outline is nicely broken up with random dark and light. I am currently reading A Guinea Pigs History of Biology by Jim Endersby, a book that examines how various species have contributed to our understanding of genetics, heredity and evolution. It is a really good book as it takes you through how our understanding of genetics developed with time. It seems quite absurd to read some of the intermediate theories knowing what we know now but with the knowledge that the scientists had at the time, you can understand that their conclusions were valid. For scientists like De Vries and Gaulton who spent their lives trying to understand how evolution might work, an example like Peppered Moth would have been invaluable. If you have forgotten your GCSE/O-level biology, Peppered Moth also exists in a (currently) rarer dark form (carbonaria). The light form is obviously good at camouflage on tree trunks but not when they are covered in soot as they were during the industrial revolution. Thus the dark form had the advantage and the light form was eaten more frequently, changing the proportions of each form in the population. As the air and the trees have become cleaner, the darker form is selected against and the pale form now predominates. Very difficult to see evolution in action normally!

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