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Author Topic:   Wells' Icons of Evolution - Peppered Moths
crashfrog
Member (Idle past 1466 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?

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Adminnemooseus
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Message 2 of 88 (102374)
04-24-2004 5:09 AM


Thread moved here from the Proposed New Topics forum.

  
PaulK
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Message 3 of 88 (102377)
04-24-2004 6:27 AM
Reply to: Message 1 by crashfrog
04-24-2004 2:44 AM


There is plenty on the web about the Wells and his claims about th Peppered Moth
You could try this to start with:
Icon of Obfuscation
The section on the Peppered Moth story includes material provided by Bruce Grant and Michael Majerus - the two leading authoritiies on the Peppered moth.
Wells is not even accurate (or honest) in what he does write.

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JonF
Member (Idle past 167 days)
Posts: 6174
Joined: 06-23-2003


Message 4 of 88 (102387)
04-24-2004 10:41 AM
Reply to: Message 1 by crashfrog
04-24-2004 2:44 AM


Wells' complaints about the peppered moth relate mostly to their natural resting places. Some photographs that were used to illustrate the contrast between light/dark moths and light/dark tree trunks were actually photos of dead moths pinned to tree trunks. There have been claims that moths do not naturally rest on exposed (and photogenic) tree trunks and therefore the idea that the average population color changed (via bird predation leading to natural selection) in the direction of better camouflage against those tree trunks is false.
These claims are hooey. Wells wrote that "peppered moths in the wild don't even rest on tree trunks" which is a flat-out lie. It's difficult to measure precisely what percentage of the time moths rest where; the little boogers are freakin' camouflaged and hard to see. Most measurement techniques (e.g. traps in various locations and counting how many moths are trapped) have at least the possibility of some bias. However, it's clear that moths rest on tree trunks a significant percentage of the time (and on what is equivalent as far as the question of this camouflage is concerned, tree trunks and tree branches and branch-trunk junctions a large percentage of the time), and it's clear that natural selection caused by some factor or factors has changed the average population color in the direction of better camouflage.
The open question is exactly how much of the natural selection that's involved is predation by birds and how much is other factors.
IMHO the best summary up to five years ago is FINE TUNING THE PEPPERED MOTH PARADIGM (a PDF document), which concludes with:
quote:
Even if all of the experiments relating to melanism in peppered moths were jettisoned, we would still possess the most massive data set on record documenting what Sewall Wright (1978) called the clearest case in which a conspicuous evolutionary process has been actually observed. Certainly there are other examples of natural selection. Our field would be in mighty bad shape if there weren’t. Industrial melanism in peppered moths remains one of the best documented and easiest to understand.
There's a good but slightly out-of-date discussion of Wells' treatment of the peppered moth story at Icon of Obfuscation: Chapter 7: Peppered Moths, which includes some nice pie charts showing where moths have been found to rest. Remember that in reference to the natural selection claim, trunks (exposed and unexposed) and branches and branch-trunk junctions are equivalent.
In 2002, Judith Hooper rekindled the controversy in Of Moths and Men: Intrigue, Tragedy and the Peppered Moth, in which she chracterized Kettlewell's original experiments as a flagrant scientific fraud. Of course the creationists love this. Her claims are refuted in many places, including Moonshine: Why the Peppered Moth Remains an Icon of Evolution
Some good current references are The peppered moth: a black and white story after all (PDF) (which includes some of the infamous "posed" pictures), and Recent History of Melanism in American Peppered Moths (PDF).

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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 5 of 88 (102395)
04-24-2004 11:49 AM
Reply to: Message 4 by JonF
04-24-2004 10:41 AM


(From a post of mine on another forum)
Regarding the famous 'peppered moths' of England -- Creationists like to twist the truth about this moth, so I will go into both sides here:
(1) Creationist (icr website)
This is taken directly from the web site:
Here's the well-told scenario. In the early 1800s, nearly all of the individual peppered moths (Biston betularia) were of a light grey, speckled color. Active mostly at night, they needed to hide by day from predatory birds. Since trees and rocks were typically covered with mottled light green, gray lichens, the moths were effectively camouflaged. A rare peppered moth exhibited a dark color and was easily seen by birds; thus they seldom survived. On average, over 98% of all the species were of the light variety, yet with both dark and light were of the same species and were fully interfertile.
Then came the industrial revolution and the air filled with soot, covering the trees and rocks with a toxic film, killing the lichens and darkening the trees. Soon the light variety of moth was easily seen while the darker were camouflaged. By the turn of the century, 98% of the moths were dark. When English medical doctor Bernard Kettlewell studied the phenomena in the 1950s, it became "Darwin's Missing Evidence"natural selection in action.
Remember that both varieties were present at the start, with the mix of genes producing lights favored over the mix of genes producing darks. As the environment changed, the dark variety had greater opportunity to pass on their genetic mix, and percentages changed. All the while, the two types were interfertile. No new genes were produced, and certainly no new species resulted. This is natural selection in action, but not evolution. Adaptation happens, but the changes are limited.
Please note that this is a creationist site and they have just said that "This is natural selection in action, but not evolution." They go on to claim that this disproves evolution because the moth varieties are not now different species. But lets look at this claim:
............................natural selection.......evolution
theory tested.................yes.....................no...
theory validated..............yes.....................no...
theory invalidated.............no.....................no...
Because evolution is not tested in this scenario it cannot be used to invalidate the theory.
Please note how this creationist website shows you exactly how the mechanism of color change in a population works. The moths did not decide to change color: there were existing genetic variations that made one population more able to survive under one condition and the other population more able to survive under a changed condition.
There are also some valid claims about some bad science done on this issue in early studies, and we will look at that issue below as well.
(2) Evolution and Natural Selection (brown university website)
Note first off that this article refers to the two varieties of the moth:
  • Biston betularia typica (the light color version) and
  • Biston betularia carbonaria (the dark color version)

In the scientific name structure (for those unfamiliar with it) we have family (Biston) species (betularia) and variety (typica or carbonaria) designations.
An important distinction is made between 'species' and 'variety' and that is that 'varieties' can interbreed: when the genetic difference is great enough that no viable offspring are created then we would then have a different 'species' - this is the scientific distinction. As we are not talking about species differentiation at this point in this scenario, the theory of evolution is not tested, per se.
From BIOLOGY by Miller & Levine, page 298:
"Kettlewell found that in unpolluted areas, more of his light-colored moths had survived. In soot-blacked areas, more of the dark-colored moths had survived. Thus Kettlewell showed that in each environment the moths that were better camoflaged had the higher survival rate. It was logical to conclude that when soot darkened the tree trunks in the area, natural selection caused the dark-colored moths to become more common. Today Kettlewell's work is considered to be a classic demonstration of natural selection in action."

Please note: "a classic demonstration of natural selection in action." Both websites agree on this.
Now lets look at a scientific critique / review of the original / early studies:
... in 1998, Michael E. N. Majerus of the Department of Genetics at the University of Cambridge carefully re-examined Kettlewell's studies, as well as many others that have since appeared. What he reported, first of all, was that Kettlewell's experiments, indicating that moth survival depends upon color-related camoflage, were generally correct:
" Differential bird predation of the typica and carbonaria forms, in habitats affected by industrial pollution to different degrees, is the primary influence on the evolution of melanism in the peppered moth."

(P. 116, Melanism - Evolution in Action, M. E. N. Majerus, Oxford University Press, New York, 1998).
However, Majerus also discovered that many of Kettlewell's experiments didn't really test the elements of the story as well as they should have. For example, in testing how likely light and dark moths were to be eaten, he placed moths on the sides of tree trunks, a place where they rarely perch in nature. He also records how well camouflaged the moths seemed to be by visual inspection. This might have seemed like a good idea at the time, but since his work it has become clear that birds see ultraviolet much better than we do, and therefore what seems well-camouflaged to the human eye may not be to a bird. In addition, neither Kettlewell nor those who checked his work were able to compensate for the degree to which migration of moths from surrounding areas might have affected the actual numbers of light and dark moths he counted in various regions of the countryside.
These criticisms have led some critics of evolution to charge that the peppered moth story is "faked," or is "known to be wrong."
Neither is true. In fact, the basic elements of the peppered moth story are quite correct. The population of dark moths rose and fell in parallel to industrial pollution, and the percentage of dark moths in the population was clearly highest in regions of the countryside that were most polluted. As Majerus, the principal scientific critic of Kettlewell's work wrote, "My view of the rise and fall of the melanic form of the peppered moth is that differential bird predation in more or less polluted regions, together with migration, are primarily responsible, almost to the exclusion of other factors."

Thus the claims on the creationist site:
  • "that Kettlewell's compelling argument has not been verified by other investigators" is outright wrong - it is verified by M. E. N. Majerus, in his book Melanism - Evolution in Action (Oxford University Press, New York, 1998).
  • "Furthermore, we now know that neither dark nor light moths ever spend their days on exposed tree trunks or rocks as depicted in the famous textbook pictures. His original associates have even admitted that the photographs were faked, that the moths were glued onto the tree." And this issue has been discussed above and answered - yes some of the initial science was not correct (or done as properly as it would be done today), but the study is validated, the effect is confirmed.

Note that Majerus is described as "the principal scientific critic of Kettlewell's work" - and he has validated and confirmed it. Also note that this website does not refer to this effect as 'proving evolution,' in fact it doesn't even discuss the theory of evolution or any relationship of it to the studies done on the moths.
POINTS IN AGREEMENT
  • there were two varieties of the moth Biston betularia in England before the 'Industrial Revolution' and on average, over 98% of all the species were of the light variety,
  • the 'Industrial Revolution' filled the air with soot, covering the trees and rocks with a toxic film, killing the lichens and darkening the trees
  • soon the light variety of moth was easily seen while the darker were camouflaged.
  • by the turn of the century, 98% of the moths were of the dark variety, and finally
  • the change in populations was due to predation of the more visible variety

Thus, even creationists "would have to say it was nature itself" that "was the source of the change."
Enjoy.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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cromwell
Inactive Member


Message 6 of 88 (103010)
04-27-2004 5:44 AM
Reply to: Message 1 by crashfrog
04-24-2004 2:44 AM


The pepped -up myth
Its not so much a case of a hoax,it’s the way the pictures were used to promote the tenet of evolution.
Kettlewells experiments were not a deliberate hoax either,however they were badly flawed and these poor examples have been used as evidence for the mechanism used to select these variants as one of natural selection.Are the observations made by Majerus really any better?
The 20 page chapter from Jonathan Wells book The icons of evolution touch on many other aspects used to back up his assertions.However he has made a sweeping statement,but he is not far off the mark.
In this book Wells makes the statement on page 140 >> What the text books don’t explain,however,is that biologists have known since 1980’s that the classical story has some serious flaws-The peppered moths in the wild do not even rest on tree trunks. <<
Later on,on page 149, Wells admits that there is only scant evidence that peppered moths do land on tree trunks..Quote from page 149... >>Since 1980,however,evidence has accumulated,showing that peppered moths do not NORMALLY rest on tree trunks.<< In this latter case he was referring to other experiments and mainly work from the Finnish zoologist Kauri Mikkolas,his experimentations with caged peppered moths and his observations of peppered moths in the wild.
What does Michael Majerus,the leading light on peppered moths say about this matter.(The links are given by Paul K and Jon F).
Majerus observed the peppered moth over a period of 32 years.If you look at his pie chart for peppered moths found in the wild,you will notice that he only observed 47 moths resting on various points of the trees.Only 12 of these in this period rested on various appropriate parts of the tree trunks.This is equivalent to around 1 moth every three years.More like the law of averages than the law of mechanics of evolution through natural selection.These moths were not pinned to the tree.At the very best you have only got scant representations.
Wells also points out that the Finnish zoologist Kauri Mikkola (mentioned above)that he only saw one peppered moth resting on a tree trunk in 25 years.
There seems to be no indication of the time periods of observation and more importantly,for how long the peppered moths actually rested on the tree trunks.A factor that would determine wether nifty birds would pick the peppered moths off of the trunks or not within a set resting time.Only a fraction of the peppered moths are going to be picked off by predators.Many contributary factors are missing.
The peppered moths spotted in the Wirral area near Manchester during the industrial revolution were noticed to be melanically different within a span of only approx 100 years light dominant to dark dominant and then back to light dominance.The industrially pollutant areas are small,so you have to consider the number of lichen free trees within that area.
How can you get a clear indication of industrial melanic natural selection due to camouflage,with such remote pickings for the predator over such a relatively small area and within a relatively short period of time? Generally speaking the peppered moths do not land on tree trunks.Not enough to base evolutionary ideas on.
In his article Wells mentions industrial melanism in ladybird beetles.Birds generally find ladybirds distasteful The bold colouring is a warning to most predators.Camouflage and predation played no part in the melanism of these insects.He also mentions the presence of other melanics in non polluted areas.Wells go’s on to say that several other factors could be involved,including possible differences in the tolerances of larvae to pollutants e.t.c. and The complex of factors that might play a role in the increase (or decrease) of melanism in moths has barely been tapped.
Kettlewells experiments were unnatural.They involved moths being released in unnaturally large quantities within a small area.They are normally mobile and spread out. The predation of these peppered moths were observed during the day.Peppered moths are night flyers and only usually land on various parts of trees at dawn.Kettlewell released them directly onto the tree trunks in broad daylight.The peppered moths are torpid during the day,so generally they would have stayed put on the trunks thus becoming easy predatory victims.
Why this is called an icon of evolution is bizarre.Because Majerus chooses to call it melanic evolution in his book,doesn’t mean that it is.Only choice words,as absurd as Wells statement first appears to be.It is merely one variant of a moth,Biston Betularia typica..light coloured peppered moth in a changing environment with,Biston betularia carbonaria..dark coloured moth. All that has happened is a fluctuation of two variants of pre-existing moths,one becoming more dominant over the other in a given period of time and then reverting back to the original dominant variation through yet unknown means.Not natural selection.
There is obviously something at work here,as there is too much evidence pointing to melanic changes within polluted areas.What it is,in reality remains a mystery.

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JonF
Member (Idle past 167 days)
Posts: 6174
Joined: 06-23-2003


Message 7 of 88 (103025)
04-27-2004 9:17 AM
Reply to: Message 6 by cromwell
04-27-2004 5:44 AM


Re: The pepped -up myth
Its not so much a case of a hoax,it’s the way the pictures were used to promote the tenet of evolution.
Not according to Wells.
In this book Wells makes the statement on page 140 >> What the text books don’t explain,however,is that biologists have known since 1980’s that the classical story has some serious flaws-The peppered moths in the wild do not even rest on tree trunks. <<
Later on,on page 149, Wells admits that there is only scant evidence that peppered moths do land on tree trunks..Quote from page 149... >>Since 1980,however,evidence has accumulated,showing that peppered moths do not NORMALLY rest on tree trunks.<< In this latter case he was referring to other experiments and mainly work from the Finnish zoologist Kauri Mikkolas,his experimentations with caged peppered moths and his observations of peppered moths in the wild.
Both of those two statements by Wells are incorrect.
YWells also wrote:: "Pictures of peppered moths camouflaged on tree trunks are used as evidence for natural selection, but biologists have known since the 1980s that the moths don’t normally rest on tree trunks, and in any event all the pictures have been staged." (as quoted at http://www.nmsr.org/text.htm#moth). Majerus' pictures were not staged.
Majerus observed the peppered moth over a period of 32 years.If you look at his pie chart for peppered moths found in the wild,you will notice that he only observed 47 moths resting on various points of the trees.Only 12 of these in this period rested on various appropriate parts of the tree trunks.
47 is a small, but statistically significant, number.
Only 25% of them rested on trunks. 100% of them rested on parts of trees in which the camouflage offered by appropriate coloration is relevant. Do you think that birds can't find moths on branches or trunk-branch junctions?
Of the 203 moths observed near traps, 76.9% of them were on parts of trees in which the camouflage offered by appropriate coloration is relevant.
"The peppered moths in the wild do not even rest on tree trunks" "peppered moths do not NORMALLY rest on tree trunks" are bald-faced lies ... you might argue that the data is inconclusive because of different results by different researchers, but Wells is totally ignoring Kettlewell's and Majerus' data.
There seems to be no indication of the time periods of observation and more importantly,for how long the peppered moths actually rested on the tree trunks.A factor that would determine wether nifty birds would pick the peppered moths off of the trunks or not within a set resting time.Only a fraction of the peppered moths are going to be picked off by predators.Many contributary factors are missing.
As acknowledged earlier, the question of the importance of bird predation is stil open.
{added in edit}
All that has happened is a fluctuation of two variants of pre-existing moths,one becoming more dominant over the other in a given period of time and then reverting back to the original dominant variation through yet unknown means.Not natural selection.
That's pretty bizarre. You acknowledge that the population was selected ... do you think it was some un-natural agency doing the selection? Do you think that the change was a random fluctuation? (hint: it wasn't, the statistics are pretty clear).
Sounds to me as if you are acknowledging natural selection but refusing to call it that.
{end addition in edit}
There is obviously something at work here,as there is too much evidence pointing to melanic changes within polluted areas.What it is,in reality remains a mystery.
There are still some mystries. There is no mystery about the overall effect; natural selection changed the population.
I suggest you read the T.O. article.
[This message has been edited by JonF, 04-27-2004]

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Loudmouth
Inactive Member


Message 8 of 88 (103133)
04-27-2004 4:45 PM


So, to sum up:
--The mocked up pictures were meant to show the difference in camoflage capabilities between phenotypes.
--The darker phenotype increased in the population in corelation with increased pollution and darkening of tree branches.
--The moths spend time on the darkened branches of trees where they are susceptible to bird predation.
Conclusion: the increase of the darker phenotype is due to predation of the less camoflaged, lighter moths. This is an example of natural selection.
Why do creationists have a problem with this study? Is it because the pictures were stressed more than the data? Should the mocked photos be a reason to throw out solid data?
Is it just me, or do creationists avoid the data?

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JonF
Member (Idle past 167 days)
Posts: 6174
Joined: 06-23-2003


Message 9 of 88 (103146)
04-27-2004 5:48 PM
Reply to: Message 8 by Loudmouth
04-27-2004 4:45 PM


--The darker phenotype increased in the population in corelation with increased pollution and darkening of tree branches
--The moths spend time on the darkened branches of trees where they are susceptible to bird predation
"Branches" is unnecessarily restricting. (I mention it only because of the stink that has been made about exactly where the little boogers rest, even though that's not crucial).
You left out:
--The lighter phenotype then increased in the population in correlation with decreased pollution and lightening of tree trunks and branches.

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cromwell
Inactive Member


Message 10 of 88 (103321)
04-28-2004 6:30 AM
Reply to: Message 7 by JonF
04-27-2004 9:17 AM


Re: The prepared myth
There is not enough time and material involved for the melanic changes to have occurred whatever data you want to look at.
If you want to be pedantic,then i agree that Wells should not have used the words Peppered moths do not land on tree trunks,as they do (extremely rarely.)But the sparsity of moths landing on tree trunks shown in the data within the short time period does not show that melanic camouflage is why the peppered moth variant numbers fluctuated.
Majerus pictures were not staged he simply had more patience than most!
Pictures of pinned moths,or those found to be resting on tree trunks,it really doesn’t matter.The point is is,that there is not enough weight of evidence to indicate that the peppered moths are prevalent enough in exposed cryptic positions to have been predatory victims within the short period of time of 100 years of the industrial revolution.(Only 50 odd years for one variant to become more dominant.)
Whatever data you look at,it is not substantial enough to have caused the changes.At the bare minimum of 12 moths seen on open points of the tree trunks or the amount caught in mercury vapour light traps 156 (approx percentage seen or caught in all open points,deducted from the 203.) This is not a significant enough amount of moths over a period of 32 year...One moth spotted every 74 days (or one moth every 974 days for the lower figure) and would this moth become a predatory victim?
Incidently these form of traps do not give a fair indication of predation of peppered moths in the wild,as moths are obviously attracted to light sources they are going to appear more often and you will get a higher figure than the moths seen naturally which.Those that could be predated upon.Realistically the figure is a lot lower.
So many very important factors are missing on this data,as mentioned before.How long did the moths rest for? Estimates and observations of predators? Tree colouration and its visual colouration at different times of the day? Time of day of the observations.What other types of moths and insects were seen on tree trunks at the same time,and if of a more distinctive shade they are going to become the victim and not the peppered moth.
The observations are just observations full of holes and used to try to prove that the peppered moths land on tree trunks. So what!They land on tree trunks once in a blue moon.This fact proves nothing given the other facts.
The melanic changes happened in small pockets of industrially polluted areas over a period of approx 100 years during the industrial revolution.In fact you have to take into consideration a measure of time for the lichen to whittle away and the possible 50% of 100 years for the dark melanic variant to have become dominant and then the reversion back to light dominant variant,found to have been the case midway through this century because the pollution was gradually controlled.You only have around 50 years to play with.
The amount of peppered moths seen on open tree points where they could have been predatory victims is therefore around 112 in a period of only 45-50 years of change.
The areas around Birmingham and the Manchester contained small pockets of woodlands nearest to the industrial smog were the moths were said to be mostly affected.Taking the figures shown and expanding the amount a little,you can get an idea of the amount of peppered moths within the woodlands.Not many,and then looking at how many very rarely land on the trees and the rarity of being victims due to the camouflage,it is easy to see that there isn’t enough substantial material to formulate conclusions that camouflage is the answer to melanic changes.Thus natural selection has only been selected naturally to promote the idealism of evolution by only speculating that the mechanism is natural selection without the true weight of evidence.

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MarkAustin
Member (Idle past 3814 days)
Posts: 122
From: London., UK
Joined: 05-23-2003


Message 11 of 88 (103333)
04-28-2004 8:41 AM
Reply to: Message 10 by cromwell
04-28-2004 6:30 AM


Re: The prepared myth
Cromwell, I am unsure exactly what point you are making. You seem to be saying that there is not enough time for the changes to occur.
However, they did. This is unquestioned. From here, the first recorded carbonaria sighting was 1848. By 1895 98% of the peppered moths in Manchester wer of this form, but within 80 years or so, the proportion had dropped dramatically: to such an extent that extinction is predicted in the next few decades. Note that in non-industrialised areas the typica form remained overwhelmingly dominant.
Regardless of the detailed explanation this is a classic example of Natural Selection in action, unless of course you are proposing some form od Non-Natural Selection. In which case what?
However, there are some recently voiced problems with some of the classical solutions:
quote:
However, Majerus also discovered that many of Kettlewell's experiments didn't really test the elements of the story as well as they should have. For example, in testing how likely light and dark moths were to be eaten, he placed moths on the sides of tree trunks, a place where they rarely perch in nature. He also records how well comoflaged the moths seemed to be by visual inspection. This might have seemed like a good idea at the time, but since his work it has become clear that birds see ultraviolet much better than we do, and therefore what seems well-camoflaged to the human eye may not be to a bird. In addition, neither Kettlewell nor those who checked his work were able to compensate for the degree to which migration of moths from surrounding areas might have affected the actual numbers of light and dark moths he counted in various regions of the countryside.
These criticisms have led some critics of evolution to charge that the peppered moth story is "faked," or is "known to be wrong."
Neither is true. In fact, the basic elements of the peppered moth story are quite correct. The population of dark moths rose and fell in parallel to industrial pollution, and the percentage of dark moths in the population was clearly highest in regions of the countryside that were most polluted. As Majerus, the principal scientific critic of Kettlewell's work wrote, "My view of the rise and fall of the melanic form of the peppered moth is that differential bird predation in more or less polluted regions, together with migration, are primarilty responsible, almost to the exclusion of other factors." (p. 155).
So, what's going on here?
Well, the best way to put it is that what we are seeing is the scientific process at its best. Majerus and other ecologists have carefully examined the details of Kettlewell's work and found them to be lacking. As Majerus explains, to be absolutely certain of exactly how natural selection produced the rise and fall of the carbonaria form, we need better experiments to show that birds (in a natural environment) really do respond to camoflage in the ways we have presumed, that the primary reason the dark moths did better in polluted areas was because of camoflage (and not other factors like behavior), and that migration rates of moths from the surrounding countryside are not so great that they overwhelm the influence of selection in local regions by birds. Until these studies are done, the peppered moth story will be incomplete. Not wrong, but incomplete.
What we do know is that the rise and fall of dark-colored moths, a phenomenon known as "industrial melanism," remains a striking and persuasive example of natural selection in action. What we have to be cautious about is attributing 100% of the work of natural selection in this case to the camoflage of the moths and their direct visibility to birds.
As can be seen from this quote, the problem is with the details, not the substance of the story.

This message is a reply to:
 Message 10 by cromwell, posted 04-28-2004 6:30 AM cromwell has replied

Replies to this message:
 Message 14 by cromwell, posted 04-28-2004 9:52 AM MarkAustin has replied

  
JonF
Member (Idle past 167 days)
Posts: 6174
Joined: 06-23-2003


Message 12 of 88 (103334)
04-28-2004 8:48 AM
Reply to: Message 10 by cromwell
04-28-2004 6:30 AM


Re: The prepared myth
There is not enough time and material involved for the melanic changes to have occurred whatever data you want to look at.
Please show your calculations.
Peppered moths do not land on tree trunks,as they do (extremely rarely.) ...This is not a significant enough amount of moths over a period of 32 year... They land on tree trunks once in a blue moon.
Please show your data and statistical calculations. Lack of large numbers of observed moths on trees is not data. The data we have indicates large percentages of moths on trees.
Incidently these form of traps do not give a fair indication of predation of peppered moths
I already noted the difficulties involved in collecting unbiased data in the message to which you replied. Nonetheless, the data is indicative.
The areas around Birmingham and the Manchester contained small pockets of woodlands nearest to the industrial smog were the moths were said to be mostly affected.Taking the figures shown and expanding the amount a little,you can get an idea of the amount of peppered moths within the woodlands.
A significant understatement of the areas involved (there's several more in England, and American areas have been studied too) and an unwarrented extrapolation.
Thus natural selection has only been selected naturally to promote the idealism of evolution by only speculating that the mechanism is natural selection without the true weight of evidence.
The statistics belie your claim.
{Aded in edit} I just came across Mallet's excellent article on teh Web; I though it was only up in PDF. I suggest your read The peppered moth: a black and white story after all. It has some good data and pointers to more.
[This message has been edited by JonF, 04-28-2004]

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 Message 10 by cromwell, posted 04-28-2004 6:30 AM cromwell has not replied

  
Percy
Member
Posts: 22388
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 13 of 88 (103339)
04-28-2004 9:16 AM
Reply to: Message 10 by cromwell
04-28-2004 6:30 AM


Re: The prepared myth
I think this issue keeps coming up because of the posed peppered moth photographs in biology textbooks, and I think it has more to do with unrealistic expectations than with anything else. Photographs in textbooks are for illustration purposes. A section on predator and prey may show a leopard prepared to pounce when the reality is that the leopard was at the San Diego zoo and was just preparing to get up. That is not misrepresentation but illustration. The biology textbook's purpose is not to present firsthand evidence, but to convey information in the best way possible, and picture's do that very effectively.
A section on camouflage might describe how a chameleon protects itself along side pictures of a chameleon first gray on a leaf and then green on the same leaf. It makes no difference that the chameleon was actually placed on the leaf by an attendant at the reptile barn of a local zoo. The purpose is to illustrate camouflage, not to present evidence for a research paper.
It turns out that peppered moth predation is too complex to properly analyze in the wild (see my book review at Book Review: Of Moths and Men), so we may never know what really happens, but there is no doubt in anyone's mind, Creationist or evolutionist, that camouflage provides a survival advantage and thereby contributes to natural selection, and this is all the textbook is trying to communicate with peppered moth photographs. The photographs aren't supposed to be from actual researchers or journal papers - they're for illustration and pedagogical purposes.
While the specifics of peppered moth predation remain elusive, and so we cannot even be sure that predation is the cause of the color changes, that the populations tend toward light and dark in response to environmental factors is very well established.
--Percy

This message is a reply to:
 Message 10 by cromwell, posted 04-28-2004 6:30 AM cromwell has not replied

  
cromwell
Inactive Member


Message 14 of 88 (103345)
04-28-2004 9:52 AM
Reply to: Message 11 by MarkAustin
04-28-2004 8:41 AM


Re: The prepared myth
>>Cromwell,I am unsure exactly what point you are making.You seem to be saying that there is not enough time for the changes to occur.<<
Not enough time for the changes to occur by the definition of natural selection because of cryptic camouflage predation.Peppered moths resting on trees and becoming the victims of predation are extremely rare,given the observations by Majerus.Changes in a period of 50 years can not be made to fit within such a time period,as the predation in the wild is almost non existant.Not enough "material" and causes to give rise to natural selection taking place.
If you read my first thread,you will see that i don't deny that something has caused the change over of dominant variants.This fact is undeniable.Wells points to it being something yet undiscovered,but due to pollutants.I am saying that it is not happening through the mechanism of natural selection.I am not saying its a fake.but i'm merely saying that the data does not prove that it can be natural selection and that other contributory factors have not been considered.
What you have quoted above illustrates the problem.Its not concrete.How birds see the prey is also something else to take into consideration.What are your views on these matters?

This message is a reply to:
 Message 11 by MarkAustin, posted 04-28-2004 8:41 AM MarkAustin has replied

Replies to this message:
 Message 15 by Percy, posted 04-28-2004 10:08 AM cromwell has not replied
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 Message 21 by MarkAustin, posted 04-29-2004 10:58 AM cromwell has not replied

  
Percy
Member
Posts: 22388
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 15 of 88 (103347)
04-28-2004 10:08 AM
Reply to: Message 14 by cromwell
04-28-2004 9:52 AM


Re: The prepared myth
Cromwell writes:
I am saying that it is not happening through the mechanism of natural selection. I am not saying its a fake. but i'm merely saying that the data does not prove that it can be natural selection and that other contributory factors have not been considered.
I agree that insufficient evidence exists to establish natural selection as the causative force behind the color changes, but I'm uncertain why you think this a significant point within the Creation/Evolution debate. Are you also arguing that there is insufficient evidence generally for natural selection as a force for change within nature?
--Percy

This message is a reply to:
 Message 14 by cromwell, posted 04-28-2004 9:52 AM cromwell has not replied

  
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