Difference between revisions of "Talk:Natural selection"

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(Industrial melanism dispute: differences between the explanations given in popularizations and what is actually known about the phenomenon)
(Industrial melanism dispute: Kettlewell's experiments were discredited)
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*there are differences between the explanations given in popularizations and introductory textbooks, which are intended for children and the lay public, and what is actually known about the phenomenon as it is discussed in journal articles intended for scientists. [http://www.pandasthumb.org/archives/2005/05/welcome_article.html (Panda's Thumb)]
 
*there are differences between the explanations given in popularizations and introductory textbooks, which are intended for children and the lay public, and what is actually known about the phenomenon as it is discussed in journal articles intended for scientists. [http://www.pandasthumb.org/archives/2005/05/welcome_article.html (Panda's Thumb)]
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Wells wrote:
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*Kettlewell's experiments supposedly demonstrated that cryptic coloration and selective bird predation are the principle causes of industrial melanism were discredited by (a) findings in the 1960's and 1970's that other factors (such as migration and non-visual selection) had to be invoked to account for observed geographical distributions, (b) reports that the rise and fall of melanism were not correlated with lichen cover on tree trunks in the U.S. or many parts of the U.K., (c) research in the 1980's showing that peppered moths in the wild do not normally rest on tree trunks (where Kettlewell conducted his experiments), and (d) revelations that all photographs of peppered moths on tree trunks have been staged, either by manually positioning live moths or by pinning or gluing dead ones. [http://www.nmsr.org/jonwells.htm]
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Now, how do we write about all this in the article? --[[User:Ed Poor|Ed Poor]] 21:00, 23 March 2007 (EDT)

Revision as of 01:00, March 24, 2007

Changes to article

Apologies, forgot to add the reason for change!

Adding more detail about the mechanisms of natural selection and known examples.

Industrial melanism dispute

Cut entire contents of section:

  • In England during the industrial revolution pollution killed mosses and lichens on tree trunks, turning them from light colours to dark brown. Before this occurred most specimens of the peppered moth Biston betularia had white wings with black spots - giving a peppered appearance. During the period with dark tree trunks (1849 to circa 1970) the white version of betularia was easily predated on by birds, decreasing the frequency of the white-wing allele. Individuals with dark wings caused by high concentrations of melanin became much more frequent and the allele frequency for melanic moths increased. When pollution levels were reduced in the late 1960s the trees gained more moss and lichens, making the trunks lighter and predation selected against melanic forms of the peppered moth. It is now thought that the proportions of white to melanic moths in England have now returned to pree-1849 levels.

Jonathan Wells points out the mistakes in this. For one thing, photos of moths resting on tree trunks had to be staged, because photographers couldn't find any moths doing this: they actually rest on the undersides of leaves. --Ed Poor 20:50, 23 March 2007 (EDT)

Even advocates of using the peppered moth story to support natural selection admit that it isn't supported by the science:

  • there are differences between the explanations given in popularizations and introductory textbooks, which are intended for children and the lay public, and what is actually known about the phenomenon as it is discussed in journal articles intended for scientists. (Panda's Thumb)

Wells wrote:

  • Kettlewell's experiments supposedly demonstrated that cryptic coloration and selective bird predation are the principle causes of industrial melanism were discredited by (a) findings in the 1960's and 1970's that other factors (such as migration and non-visual selection) had to be invoked to account for observed geographical distributions, (b) reports that the rise and fall of melanism were not correlated with lichen cover on tree trunks in the U.S. or many parts of the U.K., (c) research in the 1980's showing that peppered moths in the wild do not normally rest on tree trunks (where Kettlewell conducted his experiments), and (d) revelations that all photographs of peppered moths on tree trunks have been staged, either by manually positioning live moths or by pinning or gluing dead ones. [1]

Now, how do we write about all this in the article? --Ed Poor 21:00, 23 March 2007 (EDT)