BISTON BETULARIA

[Bruce Walsh]

"I think the point the creationists were challenging was whether the
moths
were spontaneously landing on the tree trunks, or being placed there for
experimental purposes. "

Actually, if one reads the creationist literature, the Biston experiments
themselves are not really challenged.  Rather they are presenting as
support that while the frequencies of the morphs may have changed, the moths
were fundamentally the same, and hence no evolution has occurred.  (A
rather interesting statement to say the least!) 

Likewise, the issue is not really whether birds took the moths or not, as
Kettlewell did capture-recapture experiments with adults, finding that
dark morphs (as adults) survived better than the normal forms in areas with
high levels of soot, while the reverse was true in less polluted areas. 
It is my impression that in addition to simply placing moths on trees,
batches of adults were released and then recaptured by light traps.  Hence,
something about the light vs. dark morphs results in differential survival
in two different environments.

Peace

Bruce
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