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Kettlewell and the Peppered Moths

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Jarven
#1
Jul7-13, 01:39 PM
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I'm just wondering how many of you learned the Kettlewell experiments and how it proved solid evidence for evolution in high school?

I later learned that the Kettlewell experiment was riddled with many problems (using dead moths, assuming birds have similar human vision, contradictory data in other parts of the country collected by Kettlewell and other scientists, as well as the fact that the moths don't rest vertically on the tree trunks but rather below the branches upside down).

Why is this poor experiment commonly cited as evidence for evolution in High Schools especially with the threat of creationist belief on the rise.
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Evo
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Jul7-13, 02:27 PM
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Quote Quote by Jarven View Post
I'm just wondering how many of you learned the Kettlewell experiments and how it proved solid evidence for evolution in high school?

I later learned that the Kettlewell experiment was riddled with many problems (using dead moths, assuming birds have similar human vision, contradictory data in other parts of the country collected by Kettlewell and other scientists, as well as the fact that the moths don't rest vertically on the tree trunks but rather below the branches upside down).

Why is this poor experiment commonly cited as evidence for evolution in High Schools especially with the threat of creationist belief on the rise.
You seem to have been duped by creationist/ID propaganda. The Kettlewell experiment is still considered a fine example. It is the creationist/ID camp that has spread misinformation about it.

While there were legitimate reasons why scientists did criticize Kettlewell’s experiments (including Bruce Grant's 1999 paper "Fine tuning the peppered moth paradigm," Evolution 53. 980-984 and Michael Majerus's 1998 Melanism: evolution in action, Oxford University Press, Oxford, chapters 5 and 6), none of these criticisms (density and resting place choice) involve the moths being sleepy or sluggish, and no serious experimenter suggested that Kettlewell’s results were invalid. Indeed, subsequent experiments to test these criticisms broadly confirmed Kettlewell’s results (again, see Grant, 1999, Majerus 1998, and Majerus' 2007 talk "The Peppered Moth: The Proof of Darwinian Evolution," given at the ESAB meeting in Uppsala on 23 August – also available as Powerpoint, as well as his 2009 paper "Industrial melanism in the peppered moth, Biston betularia: an excellent teaching example of Darwinian evolution in action," Evolution: Education and Outreach 2(1):63-74). Further details of these experiments are discussed in "Where Peppered Moths Rest," below.
http://ncse.com/creationism/analysis...ls-experiments
Jarven
#3
Jul7-13, 04:51 PM
P: 9
no serious experimenter suggested that Kettlewell’s results were invalid. Indeed, subsequent experiments to test these criticisms broadly confirmed Kettlewell’s results

I partially disagree with this statement; Kettlewell's results incorrectly demonstrates natural selection and his conclusion on melanic industrialism was little too simple and did not completely explain geographic distribution of carbonaria or typica.

it is our view that past attempts to assess the relative fitnesses of the forms, using formal predation experiments, have been flawed for two reasons. First, moths have been placed out on the wrong parts of trees (e.g. Howlett & Majerus, 1987; Majerus, 1989). Second, moths have been placed out in positions appropriate to their phenotype on the basis of human perception, without consideration of the UV element of the moths' pattern, or that of the substrates. The same criticism may be made of assessments of the relative crypsis of the forms of the peppered moth in different regions when these have been made by humans, with moths placed on tree trunks. The inclusion of these flawed assessments in multiple regression analyses (e.g. Lees et al., 1973; Bishop et al., 1975; Steward, 1977a,b) will lead to misleading deductions of the importance of crypsis
-A bird's eye view of the peppered moth
M. E. N. MAJERUS, C. F. A. BRUNTON & J. STALKER

Michael Majerus himself says in his book Melanism: Evolution in Action, "in most predation experiments peppered moths have been positioned on vertical tree trunks, despite the fact that they rarely chose such surfaces to rest upon in the wild" (p. 116)

The understanding of industrial melanism in the peppered moth (Biston betularia) (Lepidoptera: Geometridae)
Rory J. Howlett, Michael E. N. Majerus
Computer models based on these selective coefficients show that they are not sufficient accurately to explain observed melanic frequencies


I think a less contested example of natural selection would be a far greater way to provide evidence for school children. If the Kettlewell experiment was presented in such a manner that students could think critically about the experiment (specifically its method) rather than accepting it as "white moths are eaten on black trees because they're visible" then it would be a worthwhile experiment to talk about in class.

Evo
#4
Jul7-13, 05:17 PM
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Kettlewell and the Peppered Moths

You can read the controversy over the excerpts you posted here.

In contrast to this review, Majerus had stressed that the wealth of additional data obtained since Kettlewell's initial predation papers had not undermined the basic findings from that work, and that differential bird predation of the dark and light moths in habitats affected by industrial pollution to different degrees (directional selection) "is the primary influence of the evolution of melanism in the peppered moth".[22][23] Coyne had erred in his statement that only two peppered moths had been found on tree trunks, as the book gives the resting positions of 47 peppered moths Majerus had found in the wild between 1964 and 1996; twelve were on tree trunks (six exposed, six unexposed), twenty were at the trunk/branch joint, and fifteen resting on branches.[22] Majerus found that the review did not reflect the factual content of the book or his own views,[24] and cited an assessment by the entomologist Donald Frack that there was essentially no resemblance between the book and Coyne's review,[25] which appeared to be a summary of the Sargent et al. paper rather than Majerus's book.[26]
http://en.wikipedia.org/wiki/Peppere...on#Controversy

Also
The use of the peppered moth as an example of evolution had already come under attack by creationists who disputed it as evidence of evolution. They argued that the "peppered moth story" showed only microevolution, rather than speciation or other changes at the larger macroevolutionary scale.[27] Biologists agree that this example shows natural selection causing evolution within a species, demonstrating rapid and obvious adaptiveness with such change,[28][29] and accept that it is not proof of the theory of evolution as a whole. Although creationists accept microevolution of varieties within a kind, they claim that macroevolution does not happen. To biologists there is no dividing line between the two, and in the modern evolutionary synthesis the same mechanisms are seen operating at various scales to cause both evolution within species and speciation at a macroevolution level or wider changes, the only difference being of time and scale.[30][31]

The story of Coyne's review was taken up by intelligent design creationists, and at a seminar presenting the wedge strategy on 13 March 1999, Phillip E. Johnson said that the moths "do not sit on tree trunks", "moths had to be glued to the trunks" for pictures and that the experiments were "fraudulent" and a "scam."[32] This led Frack to exchanges with intelligent design proponent Jonathan Wells, who conceded that Majerus listed six moths on exposed tree trunks (out of 47), but argued that this was "an insignificant proportion".[33] Wells wrote an essay on the subject, a shortened version of which appeared in The Scientist of 24 May 1999, claiming that "In 25 years of fieldwork, C.A. Clarke and his colleagues found only one peppered moth on a tree trunk", and concluding that "The fact that peppered moths do not normally rest on tree trunks invalidates Kettlewell's experiments".[34]
Evo
#5
Jul7-13, 05:34 PM
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Perhaps you would be interested in the suggestions in this paper. They seem to agree with you that his work could be better utilized for school.

http://faculty.virginia.edu/evolutio...ev19-3p3-9.pdf


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