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Author | Topic: DarkStar's Collection of Quotations - Number 1 | |||||||||||||||||||
PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
Why is the issue of the moths resting in the canopy a problem for the bird-predation hypothesis ? I would have thought that it weakly supported it because the canopy seems to me to be less accessible to other potential predators - but birds certainly do hunt there.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
What's that basis for claiming that the hypothesis is restricted to the tree trunks ? So far as I know the main reason for talking about the trunks is that that was the focus of Kettlewell's experiments and his staged photographs - and because the moths usually rest elsewhere (although they do sometimes rest on the trunks). In other words it seems to be little more than a pretext for personal attacks (since Wells has no objection to "microevolution" it makes no real difference if the peppered moth story is exactly as Kettlewell proposed it or even completely wrong).
It is irrelevant to the basic idea of soot pollution, camouflage and selective predation. This message has been edited by PaulK, 08-24-2004 11:43 AM
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
So far as I know the question is the degree to which bird predation is the selective factor. The appearance and spread of the melanic form - and its disappearance after pollution was reduced - are known facts. So is the genetic basis for the colouration. So there seems to be a very good case for it being an example of natural selection even if the details are not fully established. Bird predation is very likely an important factor and applies even in the canopies.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
As I understand it bird predation is known as a factor. This article establishes that it has been established as the major (but not only) factor
Moonshine: Why the Peppered Moth Remains an Icon of Evolution
quote:
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
OK so the moths were (mainly) in the canopy in the release-and-recapture experiment.
We know that something was removing adult moths from the population - and favoured dark moths in unpolluted areas and light moths in polluted areas. Predation is the most likely explanation. We know from the other experiments that birds displayed the same selective bias, and we know that they do hunt in the canopies (and on the trunks and branches where the moths have also been seen). And if the colour during the night matters less (and I'd agree there) then the moths were probably eaten during the day while they rested. Most birds are active durng the day. Sounds like a good case for bird predation to me.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
I don't see this conversation in the same way you do.
Which if any of the follwoing statements would you disagree wiht: 1) We know that there is a selective effect going on (the release and recapture results) 2) We have good reason to beleive that bird predation is a part of it (the experiments with captive moths, combined with the fact that moths do rest on the trunks). 3) Given our background information it is reasonable to extrapolate the results of the experiments with captive moths to other parts of the trees, including the canopy. 4) While this does not constitute absolute certainty it does present a strong case that bird predation is a major factor in the selection
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
I would object to the third in that I don't believe that any of the Biblical records are eyewitness accounts from Jesus' life. And I would qualify the last with the fact that Josephus' major mention of Jesus is lkely an interpolation in whole or in part (the second, shorter message most likely is genuine).
If I accepted them all then I would agree that they constituted a strong case that there was a historical Jesus (which I believe anyway). I really don't see the problem here.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
Well as we've seen in other threads Creationists usually value their own opinions over virtually anything short of absolute proof. I don't really think that we should set "good enough to convince a closed-minded creationist" as anything other than a practical guideline for use in dealing with such individuals.
Now we can disucss why you don't feel that the experiments with captive moths were good enough to conclude that birds will take moths off tree trunks if you like. Or you can explain where you were going with your last couplweof posts but right nw I really don't see what you are objecting to.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
Unfortunately you make the mistake of believing Wells. Peppered moths have been observed resting on tree trunks.
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PaulK Member Posts: 17822 Joined: Member Rating: 2.3 |
The point you were disputing only states that the moths sometimes rest on tree trunks.
According to the chart given here Icon of Obfuscation taken from Majerus' data 6 out of 47 moths observed were on the exposed trunk - and another 6 were on unexposed locations on the trunk (typically concealed behind vegetation). The moths have been seen resting on tree trunks, in the wild, under natural conditions.
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