Question

2. Bernard Kettlewell conducted research in the 1950s which supported his hypothesis that the color and environment of peppered moths was responsible for natural selection and for changes in gene frequency. Research conducted in the 1990s has questioned the work of Kettlewell. What was wrong with Kettlewell's research? Do the new questions that have arisen disprove Kettlewell song hypothesis?

Answer 1

Kettlewell was a research fellow in Department of Zoology, University of Oxford.In 1950s he did an experiment to study about the effect of industrial revolution on peppered moths, which he called Industrial Melanism. He did experiments in two phases, in 1953 and 1955. From this he concluded that, due to pollution the birds were easily able to identify the light pepper coloured moths from trees. At the same time, dark pepper coloured moths survived, because they were not easy to distinguish from the background. Thus dark pepper coloured moths survived and the pepper coloured slowly deprived. He found that the population of these dark coloured moths were more near industries and the were not present before the industrial revolution.

There were many criticisms against the work of Kettlewell. In 1998 Michael Majerus wrote a book named Melanism: Evolution in Action, which discussed several kinds of criticism against the work of Kettlewell.

Following were the major criticisms:

1. Complete ignorance in the behaviour of moth
2. Too much artificiality in experiment conditions, protocols etc.
3. Manipulation in data
4. Difficult to replicate the same result

Despite many criticisms, Kettlewell ' s experiment still remain as a classical example of Darwin ' s Natural Selection. Thus we cannot completely disapprove the work even though there were too many second thoughts about the experiment.