Thursday, 14 June 2007

The Peppered Moth Story

The peppered Moth, Biston betularia, became famous when it was used to demonstrate the theory of natural selection. Moths are more variable within species than most animals. The Peppered Moth is a good example. It varies from almost black specimens to the normal back and white "speckled" specimens. All-dark individuals became the dominant form in certain parts of northern England and it was postulated that this was due to industrial pollution making the dark moths better camouflaged than the paler forms. Nowadays, the melanic form f. carbonaria is declining again in these areas and this would appear to coincide with cleaner industries. However, since the original work, the experiments to demonstrate advantages of the dark moths have been shown to be flawed and the situation is still one of controversy. Much has been written and this rather modest animal has assumed a significance well beyond what might have been expected. A complete on-line lecture by Prof. Laurence Cook of Manchester Metropolitan University explains the complex research clearly.

I have caught a very dark example, but not since I've lived here, but the ones I catch are quite variable. below are three example from the last few days.

This is the palest of the ones I've caught this year.

This is about the average colour I catch.

This is the darkest one I've caught this year.

This one from the 2nd June 2004 is the darkest I've caught at St Margaret's.

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