Re: My last word

Brian D Harper (
Fri, 23 Apr 1999 16:07:34 -0700

At 05:21 PM 4/21/99 EDT, Kevin wrote:

>In a message dated 4/21/99 12:02:52 PM Mountain Daylight Time,
> writes:
>> >To my knowledge, no one said that Wells did not have the RIGHT to raise
>> >objections. What we were saying is that his lack of knowledge of the
>> >peppered moth and his lack of experience in biological field work (and
>> >apparantly in scientific research in general), not to mention his more
>> >political ambitions, has led him to make foolish accussations that he
>> >cannot
>> >support, yet stubbornly clings to even after more knowledgeable and
>> >experienced people have explained how and why he is wrong. We do not
>> >object
>> >to Wells because he has the wrong credentials; we object to Wells because
>> >he is a fool.
>> >
>> How nice for you. I have no expertise in industrial melanism,
>> biological field work etc. I do know something, however, about
>> experimental methods. Nothing Wells has said in this regard
>> strikes me as foolish. In fact, quite the opposite.
>Then I guess you haven't been paying attention to what Don Frack has been

Well, as I indicated previously, I have only scanned Don's posts. I received a
copy of Majerus book today. I'll look at it first and then go back and look
at Don's posts again.


>> BH:===
>> >>
>> >> What occurred to me originally was that a photograph of a moth
>> >> sitting on an exposed tree trunk will reinforce not only the
>> >> idea of increased visibility due to coloration but also increased
>> >> visibility due to being out in the open on an exposed tree trunk.
>> >>
>> >
>> KO:===
>> >If you did not already know that the moths were resting on tree trunks,
>> >could you distinguish that from say a large diameter bough? The point is
>> >still, though, that the PLACE mattered little, only the color contrast.
>> >
>> Interesting. Below you give differences in hunting styles which
>> show that the place does matter. Of course, this would matter
>> little wrt the central claim that bird predation is the cause
>> for the differential success of the two colorations. Nevertheless,
>> it is an indication that place *might* matter.
>Look again at what I said: I said the place matters little, I didn't say it
>didn't matter at all.

OK. Nevertheless, it seems that Majerus disagrees:

#"If the relative fitness of the morphs of the peppered moth does depend
#on their crypsis, the resting position is crucially important to the estimation
#of fitness differences between the morphs. This is particularly the case
#in changing or intermediate habitats with respect to pollution, because in
#such habits the distribution of lichens on trees is likely to be more
#heterogeneous than in very unpolluted or very polluted habitats. It is
#therefore valuable to consider, albeit briefly, on which parts of trees
#lichens of different types seem to grow in different situations."
# -- Majerus p. 123

>By the way, the differences in hunting styles do not
>increase the probability that place would matter. Pattern recognition
>predators can still be fooled by camouflage; the classical experiments and
>the more recent follow-up experiments demonstrated that when the moths did
>rest on trunks that pattern recognition predators still preferentially took
>moths whose color had the highest contrast with the background. As such,
>since camouflage is even more effective against movement/color contrast
>predators, you would expect the preferential predation would be even stronger
>in the canopy.
>> Has anyone demonstrated
>> empirically that selective predation occurs where moths normally
>> rest?
>According to Majerus, yes; the details and references are in his book.

Perhaps you could help me out a little. What I've found so far seems
to contradict what you say. For example:

#"Although observations of peppered moths being taken from natural resting
#positions are still lacking and are urgently needed, it is highly probable
#that predation levels are significant." -- Majerus

and then a little later on the same page:

#"Yet, surprisingly, experiments to show formally that the degree of crypsis
#of the different peppered moth forms does affect the level of predation
#inflicted on them by birds have never been carried out." --Majerus

>> As another possible influence of location, would you happen to
>> know off hand whether lichens grow better on tree trunks as opposed
>> to branches?
>It depends upon the species, but generally no.

Once again, it seems that you disagree with Majerus.


>> Please accept my humblest apologies if I am acting overly
>> foolish :).
>For someone who criticizes others for discourtesy in their writings, you can
>be very sarcastic when you want to be.

Well, I guess you've probably caught me on that one ;-).


Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University

"All kinds of private metaphysics and theology have
grown like weeds in the garden of thermodynamics"
-- E. H. Hiebert