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Author Topic:   Peppered Moths and Natural Selection
Belfry
Member (Idle past 4154 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 36 of 350 (261681)
11-20-2005 9:57 PM
Reply to: Message 13 by randman
11-20-2005 7:04 PM


Re: ignorance is bliss for some evos
One more thing to add, re:

2. Secondly, birds have the ability to see in the UV spectrum and the ignorance of that basic fact renders moot any conclusions about what birds actually see in this instance.

Check this out:

Majerus M.E.N.; Brunton C.F.A.; Stalker J. A bird’s eye view of the peppered moth. Journal of Evolutionary Biology, Volume 13, Number 2, March 2000, pp. 155-159(5)

...One important aspect of early work evaluating the relative crypsis of the forms of B. betularia on tree trunks with different lichen flora was the reliance on human observers. Humans, however, do not have the same visual capabilities as birds. Birds have well-developed ultraviolet (UV) vision, an important component of their colour processing system that affects many aspects of behaviour, including prey detection. We examined the UV characteristics of the two forms of B. betularia and a number of foliose and crustose lichens. In human visible light the speckled form typica appeared cyptic when seen against a background of foliose lichen, whereas the dark form carbonaria was conspicuous. Under UV light the situation was reversed. The foliose lichens absorbed UV and appeared dark as did carbonaria. Typica, however, reflected UV and was conspicuous. Against crustose lichens, typica was less visible than carbonaria in both visible and UV light. These findings are considered in relation to the distribution and recolonization of trees by lichens and the resting behaviour of B. betularia.

There have also been studies showing that these moths do rest on tree branches during the day, and that they preferentially choose resting locations where they camouflage well. I can provide citations if necessary.


This message is a reply to:
 Message 13 by randman, posted 11-20-2005 7:04 PM randman has responded

Replies to this message:
 Message 38 by randman, posted 11-20-2005 10:28 PM Belfry has not yet responded

  
Belfry
Member (Idle past 4154 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 107 of 350 (262278)
11-22-2005 6:51 AM
Reply to: Message 52 by randman
11-20-2005 11:45 PM


Re: my response, bad as it was the first time and worse for repetition.
Why did darker moths increase wildly in population to 80% of the moth population in areas with no substantial industrial pollution?

That's misleading. Your quote actually says that the melanics "reached a frequency of 80%," without giving any indication of the degree to which this percentage differs from expectation. In fact, Lees and Creed state in that 1975 study that the increases and decreases at the individual study sites weren't statistically significant individually, but when the data were pooled by region a significant result could be reported.

There are possible population-dynamics explanations, but I'm reluctant to go into them without finding studies to support them in this case.


This message is a reply to:
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Belfry
Member (Idle past 4154 days)
Posts: 177
From: Ocala, FL
Joined: 11-05-2005


Message 222 of 350 (355145)
10-08-2006 8:11 AM
Reply to: Message 219 by MartinV
10-08-2006 5:51 AM


Re: More Ignorance.
MartinV writes:

So why so many random mutation during industrial revolution have led to melanic forms, but we did not found any random mutation (even before and after) that led to other colors as melanic ones? Were mutations during the period really random? If directed, would not be that case of melanic moths somehow falsify darwinism?


I expect that RAZD will have no trouble answering you, but I'll just put in that it's because variations in melanism are very common among insects (and in other animals, too - as I see WK has already beaten me to pointing out). It's not a matter of mutating to form a novel pigment, or to express it in very different regions of the body or wings. It's mostly a matter of changing the degree of saturation of a pigment that is already produced.

Here's a link to a good article that gives a primer to melanism in insects, as well as what is known about the genetics, at least as of 2003: True, JR. 2003. Insect melanism: the molecules matter. Trends in Ecology and Evolution. 18(2): 640-647. (.pdf)

Edit: Argh, now I see that WK beat me to all of my points. I was too slow to finish my post. But my link is still worth bringing in!

Edited by Belfry, : No reason given.

Edited by Belfry, : No reason given.


This message is a reply to:
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