Peppered Moth - Evolution

Evolution

The evolution of the peppered moth over the last two hundred years has been studied in detail. At the start of this period, the vast majority of peppered moths had light coloured wing patterns which effectively camouflaged them against the light-coloured trees and lichens upon which they rested. However, due to widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees which peppered moths rested on became blackened by soot, causing most of the light-coloured moths, or typica, to die off due to predation. At the same time, the dark-coloured, or melanic, moths, carbonaria, flourished because they could hide on the darkened trees.

Since then, with improved environmental standards, light-coloured peppered moths have again become common, and the dramatic change in the peppered moth's population has remained a subject of much interest and study. This has led to the coining of the term "industrial melanism" to refer to the genetic darkening of species in response to pollutants. As a result of the relatively simple and easy-to-understand circumstances of the adaptation, the peppered moth has become a common example used in explaining or demonstrating natural selection to laypeople and classroom students.

The first carbonaria morph was recorded by Edleston in Manchester in 1848, and over the subsequent years it increased in frequency. Predation experiments, particularly by Bernard Kettlewell, established that the agent of selection was birds who preyed on the carbonaria morph.

Jonathan Wells is one of a number of creationists who have criticized the use of peppered moth melanism as an example of evolution in action. In his book Icons of Evolution, Wells alleges that peppered moth studies, and in particular Kettlewell's experiments, were erroneous. Similarly, in 2002 Judith Hooper repeatedly implied fraud and error in Kettlewell's experiments in her book titled Of moths and men. Despite some valid criticisms of the early experiments, there has been no evidence of fraud. Subsequent experiments and observations have supported the initial evolutionary explanation of the phenomenon.