Claim CB601.4:
In one of Bernard Kettlewell's peppered moth studies, his moth recapture
rate increased greatly beginning on July 1. July 1 was also the date on
which E. B. Ford sent Kettlewell a letter commiserating with him for the
low recapture rates. This suggests that Kettlewell cheated to increase
his recapture rates.
Source:
Hooper, Judith, 2002. Of Moths and Men: An Evolutionary Tale. New
York: W.W. Norton.
Response:
- Kettlewell would not have received Ford's letter before the increase in
his recapture rate had already begun. The collection of July 1 was
completed by the early morning. Since Ford's letter would have arrived
after, it could not have been a factor.
- Kettlewell recaptured more moths after July 1 because he was releasing
more moths then. The number of moths he collected is not significantly
different from the collections one would expect on the basis of the
number of moths released in the two prior days (Young 2004). He
probably released more moths because the moths he was rearing reached
adulthood then.
- Much of the remaining variation in recapture rate might be explained by
moonlight. The low recapture rates occurred when the moon was full,
and for many species of moths, a full moon reduces the numbers caught
in light traps.
- Kettlewell's conclusions were based not only on his recapture
experiment but also on three other investigations. The same
conclusions were found by many other experiments on peppered and other
moths by other researchers (Grant 1999).
Links:
Young, Matt, 2004. Moonshine: Why the peppered moth remains an icon of
evolution. http://www.talkreason.org/articles/moonshine.cfm
or
http://www.talkdesign.org/faqs/moonshine.htm
References:
created 2004-1-28
