Reviewing the Mystery… Why is the dark form becoming more common in areas downwind of manufacturing centers?

The Peppered Moth Biston betularia f. typica Biston betularia f. carbonaria

1950 Frequency of dark form Centers of pollution 1700 1800 1900 2000 Glasgow Manchester London 1700 1800 1900 2000 1600

Light & Dark Forms lichen-covered tree soot-covered tree

Natural Section & the Mystery Phenomenon J.W. Tutt (1858-1911) E.B. Ford (1901-1988) The spread of the dark form is due to its physiological superiority over the light form. The spread is limited to areas darkened by pollution owing to the handicap of dark coloration in unpolluted environments.

Mystery Phenomenon Part 3

The peppered moth Biston betularia H.B.D. Kettlewell The peppered moth Biston betularia (1907-1979)

Kettlewell’s Investigations Mark-release-recapture experiment

Film: Evolution in Progress

Kettlewell’s m-r-r results 2x as likely to survive.

Kettlewell’s m-m-r results 2x as likely to survive.

Observations: bird predation order

What are experiments?

Are experiments necessary for progress in science?

Have Kettlewell’s experiments convinced you that Ford’s theory is correct?

The Mystery Continues Kettlewell’s Conclusions Not universally accepted Issues with experimental design. Lack of knowledge of behavior & ecology of moth. Other scientists worked on the moth

M. E. Majerus Ford

Problems & Solutions Kettlewell Biston betularia found at rest on a horizontal tree branch (M. Majerus 2009)

Expectations J.W. Tutt (1858-1911) M.E. Majerus (1954-2009)

And What of the Moth? Frequency of dark form Centers of pollution 1700 Glasgow Manchester London 1700 1800 1900 2000 1600

The Great Smog of 1952 4- day smog event Nelson's Column, London 4- day smog event Reported that 4,000 people died Recent research puts deaths at 12,000 10,000 people ill

Clean Air Act 1956 Britain now had strict air pollution laws in place. What happened to the frequency of the dark form?

The Mystery Phenomenon ? Cooke Majerus Kettlewell Tutt Harrison Ford 165 years & counting

Is that the Complete Story?

Details, details. 1’. The peppered moths has two dark forms, not one. Biston betularia f. typica Biston betularia f. carbonaria Biston betularia f. insularia

When is it Enough? Carbonaria is common in some rural areas (unpolluted). Dark forms of other species have evolved for other reasons. Scientific controversies not covered in detail.

What Should Science Teachers Do? How much detail should science teachers give? How can simplified versions of a scientific account be useful? What problems can arise using simplified versions? Is there ever a “complete” version?