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Author Topic:   Wells' Icons of Evolution - Peppered Moths
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 1 of 88 (102359)
04-24-2004 2:44 AM


In a discussion where environmental change leading to allele shift in peppered moths was mentioned, Servant2thecause attempted to refute the changing allele frequencies by noting:
If you are referring to the same peppered moth color-change from white to black as mentioned in most textbooks, that was a hoax
and going on to quote Wells, from Icons of Evolution:
quote:
Manually positioned moths have also been used to make television nature documentaries. University of Massachusetts biologist Theodore Sargent told a Washington Times reported in 1999 that he once glued some dead specimens on a tree trunk for a TV documentary about peppered moths Staged photos may have been reasonable when biologists thought they were simulating the normal resting-places of peppered moths. By the late 1980’s, however, the practice should have stopped. Yet according to Sargent, a lot of faked photographs have been made since then Defenders of the classical story typically argue that, despite being staged, the photographs illustrate the true cause of melanism. The problem is that it is precisely the cause of melanisim that is in dispute.
Before the 1980’s most investigators shared Kettlewell’s assumption, and many of them found it convenient to conduct predation experiments using dead specimens glued or pinned to tree trunks. Kettlewell himself considered this a bad idea, and even some biologists who used dead moths suspected that the technique was unsatisfactory Since 1980, however, evidence has accumulating showing that peppered moths do not normally rest on tree trunks. Fnnish zoologist Kauri Mikkola reported an experiment in 1984 in which he used caged moths to assess normal resting places. Mikkola observed that ‘the normal resting place of the Peppered Moth is beneath small, more or less horizontal branches probably high up in the canopies’
--Dr. Well, Jonathon. Icons of Evolution. 2000. Page 149-151.
Since this happened in a Great Debate topic, I've chosen to move the discussion here.
The quote S2C gave doesn't seem to refer to changing allele frequencies of the moths as a hoax, but rather, some detail of their positioning on trees that I'm not too clear on. It's been my understanding that regardless of where they sit on the tree, peppered moth melanin levels changed in the population because of the darkening of their environment by pollutants. That inference, as far as I'm aware, has never been contradicted by evidence.
I've never read the book in question. Is there context that S2C forgot that would imply that allele frequencies don't change in peppered moths? Or did S2C simply not understand the point under scrutiny or the quote in question? What part of the moth story is the hoax?

Replies to this message:
 Message 3 by PaulK, posted 04-24-2004 6:27 AM crashfrog has not replied
 Message 4 by JonF, posted 04-24-2004 10:41 AM crashfrog has not replied
 Message 6 by cromwell, posted 04-27-2004 5:44 AM crashfrog has not replied
 Message 49 by Rick Rose, posted 05-15-2004 11:43 PM crashfrog has replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 50 of 88 (108507)
05-15-2004 11:49 PM
Reply to: Message 49 by Rick Rose
05-15-2004 11:43 PM


So how can an evolutionist or a creationist use this argument to support thier respective beliefs?
You said it yourself:
The black moths were always present, but now they became predominant.
That's evolution - a change in a population's allele frequencies (specifically the frequency of the black coloration allele) as a result of a selecting interaction with the environment.
Of course, then you say:
The species didn't change.
which is simply not true - the species did change: the black allele increased in frequency. Changing allele frequency is a change within species.

This message is a reply to:
 Message 49 by Rick Rose, posted 05-15-2004 11:43 PM Rick Rose has replied

Replies to this message:
 Message 51 by Rick Rose, posted 05-17-2004 2:35 PM crashfrog has replied

  
crashfrog
Member (Idle past 1467 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 54 of 88 (108967)
05-18-2004 1:37 AM
Reply to: Message 51 by Rick Rose
05-17-2004 2:35 PM


So frequency of population changed, but genetic structure of black or white moth did not change.
Not as a result of pollution, no. But we presume that a genetic structure change did occur at some point prior to the selection event - the mutation that created black moths in the first place.
We presume this because mutation is the only observed source of new alleles.
What we observed with the moths is natural selection, yes. Combined with the mutation that must have occured, that represents evolution.

This message is a reply to:
 Message 51 by Rick Rose, posted 05-17-2004 2:35 PM Rick Rose has replied

Replies to this message:
 Message 55 by Rick Rose, posted 05-18-2004 1:57 PM crashfrog has not replied

  
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