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Author Topic:   Peppered Moths and Natural Selection
JonF
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Posts: 2831
Joined: 06-23-2003
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Message 15 of 346 (261646)
11-20-2005 8:01 PM
Reply to: Message 13 by randman
11-20-2005 7:04 PM


Re: ignorance is bliss for some evos
1. First off, no the study does not rule out all the various factors that could have influenced whether lightly colored or darkly colored moths became more dominant as a result of soot. It could be something else entirely, perhaps another aspect of pollution, coincidence, etc,...

The statistics have been done. The correlation between pollution and relative frequencies of moth populations is very significant. It's not a coincidence. Perhaps another aspect of pollution ... but, if so, so what? The conclusion is that natural selection changed the population; exactly how this happened is an important question but is not going to change the primary conclusion.

The statistics also demonstrate that bird predation is the major influence on the balance between the two types. There are probably other effects, and there is disagreement about those effects and their relative importance, but bird predation is #1.

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.

Nobody has made any conclusions about what birds actually see (there have been some hypotheses). The fact that birds can see in UV does not render the actual conclusions of the studies moot.

3. Peppered moths are nocturnal and so releasing them in the day-time to draw conclusions about their behaviour also makes the study based on faulty data.

Why? They were never recaptured before the next night, and sometimes two nights passed before recapture.

5. I have heard but not verified that these same experiments were repeated elsewhere in the world with the opposite results. As such, since the experiment is not repeatable, it falls down on that merit as well.

You heard wrong. The same experiments have been repeated elsewhere in the UK and in the U.S. with the same results. The results are repeatable and have been repeated.

See Moonshine: Why the Peppered Moth Remains an Icon of Evolution, The peppered moth: a black and white story after all, FINE TUNING THE PEPPERED MOTH PARADIGM, and Recent History of Melanism in American Peppered Moths.


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JonF
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Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 86 of 346 (261852)
11-21-2005 9:43 AM
Reply to: Message 42 by randman
11-20-2005 10:41 PM


Re: my response
1. First off, no the study does not rule out all the various factors that could have influenced whether lightly colored or darkly colored moths became more dominant as a result of soot. It could be something else entirely, perhaps another aspect of pollution, coincidence, etc,...

Unless someone can show where all of the other potential factors have been ruled out, please don't respond until you (evos here) provide that.

Irrelevant. The conclusion is that natural selection, largely due to bird predation, changed the distribution of light and dark moths. It is not necessary to rule out all other protential factors to consider that conclusion justified.

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.

It appears one study indicates UV vision reverses things, but perhaps I am misreading that. If you want to get into this subtopic, I'll answer you in that regard.

Let's see the cite.

3. Peppered moths are nocturnal and so releasing them in the day-time to draw conclusions about their behaviour also makes the study based on faulty data.

Please cite the studies that show statistics related to bird versus bat predation, day-light habits, etc....Releasing moths into the day-light where they are stunned by the change is not a valid approach.

The moths were released in the morning about the time that moths are settling in for the day.

As I psoted before, see Moonshine: Why the Peppered Moth Remains an Icon of Evolution, The peppered moth: a black and white story after all, FINE TUNING THE PEPPERED MOTH PARADIGM, and Recent History of Melanism in American Peppered Moths.

4. In reality, birds are not even the primary predator of peppered moths, but rather bats are. Bats method of sensing prey is totally different, and relies on sound waves and thus bats tend to capture moths in flight rather than while they are resting. This fact further makes the claims of the study to be somewhat fantastic in nature and without solid scientific standing.

Please cite where bat predation factors are accounted for.

Please demponstrate that it is necesary to accounht for bat predation.

Since bats apparently do not select by color, the effect of bat predation would be to somewhat blur but not remove the effect of bird predation. If 95% of all moths are eaten by bats and 5% are eaten by birds, that's still enough for differential bird predation to affect the distribution of colors. So, you need to provide evidence of bat predation being more significant than bird predation and the statistical analysis that demonstrates that the effect of bat predation can remove the effect of differential bird predation.

. I have heard but not verified that these same experiments were repeated elsewhere in the world with the opposite results. As such, since the experiment is not repeatable, it falls down on that merit as well.

You heard wrong. The same experiments have been repeated elsewhere in the UK and in the U.S. with the same results. The results are repeatable and have been repeated. See, I can repeat myself too. Don't bother to repeat yourself again until you've read my references.

Yet again, see Moonshine: Why the Peppered Moth Remains an Icon of Evolution, The peppered moth: a black and white story after all, FINE TUNING THE PEPPERED MOTH PARADIGM, and Recent History of Melanism in American Peppered Moths.


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JonF
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Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 128 of 346 (347363)
09-07-2006 7:48 PM
Reply to: Message 126 by MartinV
09-07-2006 3:53 PM


Peppered moths are _really_ hard to find
If they are hard to find, where do they rest during day? Are these
places accessible for birds to pick them? If it is so, what are the difficulties for a scientist to make a photo of them in their resting place?

From Fine Tuning the Peppered Moth Paradigm:

quote:
As to where peppered moths actually do take up daytime resting sites, Majerus himself reports by far the greatest number of sightings among moth workers. In his 34 years of moth hunting, Majerus has discovered 47 peppered moths at rest by day in the wild. (The large samples of peppered moths used to calculate melanic frequencies in local populations come from operating light traps and assembling [pheromone] traps at night. It's rare, indeed, to find a peppered moth away from a trap by day even where the species is abundant.) Majerus separates into categories the position on trees where the moths were located (trunk, trunk/branch joint, branches). While the trunk/branch joint was the most common site, his data indicate that the moths do not all rest in the same place. As Clarke et al. (1994) put it: "Moths habitually resting in only one place will be habitually sought there." Mikkola (1984), based on his observations of moths kept in captivity, suggested that peppered moths hide by day on the underside of branches in the canopy. Grant and Howlett (1988) showed that captive moths move to whatever end of their holding pen light enters (if the light enters from the bottom of the pen, the moths will sit on the floor). Perhaps Mikkola's conclusion is correct, but perhaps his evidence is an artifact of his apparatus. In truth, we still don't know the natural hiding places of peppered moths.

{Emphasis added}

34 years. He saw 47 moths, far more than any other researcher. Yup, they're hard to find and pose. Got any suggestions for how to get a light-colored moth and a dark-colored moth together in a well-lit area that demonstrates teh difference in camouflage?


This message is a reply to:
 Message 126 by MartinV, posted 09-07-2006 3:53 PM MartinV has responded

Replies to this message:
 Message 142 by MartinV, posted 09-08-2006 12:48 PM JonF has responded

  
JonF
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Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 147 of 346 (347567)
09-08-2006 2:01 PM
Reply to: Message 142 by MartinV
09-08-2006 12:48 PM


Re: Another antidarwinistic hypothesis for industrial melanism
Because we know, that some locusts (grasshopers) as Oeddipoda caerulescens or Oedipoda germanica change their colour on on wings during larval stage through vision channels (Suchantke:"Metamorphosen in Insektenreich").

Is this not also possible explanation for peppered moths?

That peppered moths change color according environment (whatever the mechanism is) without any selective pressure from birds and that this case of peppered moths do corroborate neither darwinistic selectionism nor neodarwinism as theory.

It is not a possible explanation. You should learn something about the subject before attempting to criticise. The peppered moth has been extensively studied, and individual moths do not change color over time or under any kind of pressure or environment. The statistics of the populations have been investigated in many experiments. The color differences are due to a mutation in a gene that causes melanin production. The "dark" allele is dominant, so a moth must have two "light" alleles to be light. The dark mutation is "recurrent", in that it arises anew once in a while; but, before industrialization, the dark moths were at such a disadvantage that the light moths were far in the majority.

We know that the coloration is due to genetics and nothing else, and we know that dark and light moths are that way because of their alleles.


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JonF
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Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 148 of 346 (347571)
09-08-2006 2:12 PM
Reply to: Message 142 by MartinV
09-08-2006 12:48 PM


Re: Another antidarwinistic hypothesis for industrial melanism
It may be then only unproven darwinistic assumption, that peppered moths are eaten during day by birds and that there exists selection pressure at all.

From Peppered moth predation experiments:

quote:
Moths were released into a large (18m by 6m) aviary, where they were fed on by great tits, (Parus major).

ABE: From the distinctly anti-evolution Jonathan Wells at Second Thoughts about Peppered Moths:

quote:
In the 1950’s, British entomologist Bernard Kettlewell set out to resolve the issue empirically. Like Tutt, Kettlewell believed that industrial melanism was due to cryptic coloration and selective predation, and he used three experimental approaches to test the theory. First, he estimated the moths’ camouflage efficiency on various backgrounds, as judged by the human eye. Second, he directly observed bird predation through binoculars. Third, he marked and released larger numbers of moths, then recaptured some and compared the pre-release to post-recapture proportions.

Kettlewell’s first experiment was conducted in an aviary containing a pair of nesting birds and their young. He released peppered moths into the aviary, and watched through binoculars as they settled onto resting sites and were subsequently eaten by the birds. Kettlewell (1955) thus established that birds do, in fact, prey on resting peppered moths.



{emphasis added}

{end ABE}

I personally will be very glad to read some article about how "palatable" peppered moths really are, if it is convinient for birds (and simple) to look after them on bottom parts of branches in the canopy.

Well, then, hie thee to a library and start with Kettlewells's 1953 and 1955 papers. So far you haven't done even an Internet search.

Some experiments in the aviary where birds have nothing else to choise for eating and where peppered moths are light accessible on wall is not of relevance.

How do you know they had no other choices? How do you know how accessible the moths were? Even if there was nothing else to eat and the moths were accessible, why is it not relevant? It shows that birds will eat peppered moths and not avoid them.

Edited by JonF, : Added quote from Wells


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JonF
Member
Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 261 of 346 (418448)
08-28-2007 8:23 AM


Differential bird predation "once again supported by empirical evidence"
That's the conclusion of a new study by Michael Majerus, specifically designed to test the bird predation hypothesis.

A PDF transcription of his talk about it at ESEB in Uppsala is available at The Peppered Moth: The Proof of Darwinian Evolution. Hopfully the PowerPoint slides will be available soon and, of course, we look forward to a peer-reviewed publication.

The Panda's Thumb has a blurb at Peppered Moths: We Told You So.


  
JonF
Member
Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 264 of 346 (418594)
08-29-2007 7:53 AM
Reply to: Message 263 by Minnemooseus
08-29-2007 1:06 AM


Re: Peppered Moth at Panda's Thumb
There's a new discussion of the state of the art things Peppered Moth at Panda's Thumb

Beat'cha to it! Message 261.


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JonF
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Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 265 of 346 (418937)
08-31-2007 8:57 AM


PPT file and data now available
Now both Majerus' script and PowerPoint presentation are available at Majerus Lab Evolutionary Genetics Group. Some highlights:

quote:
The additional experiment that has been done addresses the question of bat predation. This arose directly from Hopper’s book, for it reveals Hooper’s lack of understanding of Darwinian selection. Hooper (2002, p. 270) raises the question of bats as predators of peppered moths. She states that “Kettlewell himself admitted that they {bats} probably accounted for 90% of the predation of adult moths.”
By e-mail in 2000, she pointed out to me that Kettlewell had “said that this didn’t matter because it wasn’t selective—ergo, even if only 10% of the predation was by birds hunting by sight, that 10% is what makes the difference and drives evolution”. Hooper thought that there were flaws in this argument and asked me about this.
By phone I said I agreed with Kettlewell and explained why (Hooper, 2002, p. 270). But not understanding how selection operates, Hooper didn’t get it, and concludes, ‘Can we really be sure that bat predation is not selective….?'




Predation by bats

Form

Flew and lost

Did not fly

Caught by bats

a) Camb. 2003

carbonaria

114

35

51

typica

107

39

54

b) Camb. 2004

carbonaria

104

43

53

typica

117

36

47

c) New Forest 2005

carbonaria

100

39

61

typica

95

32

73

d) Leeds 2005

carbonaria

126

31

43

typica

132

31

37


quote:
From the data shown here, it is obvious that there are no significant differences in the predation of the two forms. Across the four runs, 208 carbonaria and 211 typica were taken.
So pipistrelle bats do not show differential selection of typica compared to carbonaria or viceversa.

quote:
During the main predation experiment, I have had occasion to spend time carefully scrutinizing the trunks, branches and twigs of a limited set of trees at the experimental site. During this time I have found 135 peppered moths, resting in what I have no reason to presume are not their freely chosen natural resting sites.
The position of each moth was scored for resting site (trunk, branch, twig); height above ground; on trunks, north or south half; on branches, top or bottom half. Sex and form of each moth was also recorded.


Where peppered moths rest by day (2001-2006)

Trunks

Branches

Twigs

Totals

Males

28

40

11

79

Females

20

30

6

56

Totals

48

70

17

135


quote:
Results (2001-2006) are that:
i) The majority (50.4%) of moths rest on lateral branches
ii) That of the moths on lateral branches, the majority (89%) rest on the lower half of the branch
iii) That a significant proportion of moths (37%) do rest on tree trunks
iv) That of those that rest on trunks, the majority (86.8%) rest on the north, rather than the south half.
v) That a minority of moths (12.6%) rest under or among twigs
vi) That there was no significant difference in the resting sites of males and females.
vii) There was no significant differences in the resting sites used by typica, carbonaria or insularia forms.

And here are some of the moths.
While the results may be somewhat biased towards lower parts of the tree, due to sampling technique, I believe that they give the best field evidence that we have to date of where peppered moths spend the day.



Click to enlarge

Click to enlarge

Click to enlarge


Click to enlarge

quote:
When you see moths like this, they are fairly easy to see. However, I have, through this work, come to understand why Clarke et al. (1985) wrote, ‘In 25 years we have only found two betularia on the tree trunks or walls adjacent to our traps and none elsewhere”. So, Can you see it?


Click to enlarge

Click to enlarge

quote:
The basic results of the predation experiment are shown here, with the numbers of moths of each form available for predation and the numbers eaten given. The bottom line is that a significantly greater proportion of carbonaria were eaten than typica.
A number of species of bird were observed preying on the moths: These included: robins, hedge sparrows, a lesser-spotted woodpecker, great tits, blue tits, blackbirds, starlings, wrens and magpies.




Numbers of the two forms available
for predation and predated (2002-2007)

Year

Numbers available for predators

Numbers eaten

typica

carbonaria

typica

carbonaria

2002

706

101

162

31

2003

731

82

204

24

2004

751

53

128

17

2005

763

58

166

18

2006

774

34

145

6

2007

797

14

158

4


Predation (4) selection coefficients
selection coefficient against carbonaria compared to typica

Year

Expected selection against
carb. based on form frequency
differences between years

Observed selection against
carb. from selection
experiment

2001

0.239

Not done

2002

0.337

0.252

2003

-0.096

0.046

2004

0.435

0.469

2005

0.63

0.299

2006

0.13

-0.061

2007

predicti on

0.306


quote:
  • Average selection against carbonaria from form frequency data = 0.286
  • Average selection against carbonaria from predation experiment = 0.219
  • Correlation coefficient for expected compared to observed for years 2002-2006 = 0.75169

From the data, the selection coefficient needed to account for the decline in carbonaria frequency for each year between 2001 and 2007 can be compared to the selection coefficient observed in the predation experiment for each year 2002-2007. Here, were bird predation to be a causative factor of changes in carbonaria frequency, compared to typica, the observed frequency in one year should be a consequence of the predation the previous year. So, I do not have predation data to account for changes from 2001-2, and the predation observed in 2007, should be predictive of frequencies in 2008.
However, we can look at two things here. First, the average selection against carbonaria over the period is not very different between that gained from the form frequency data and that observed in the predation experiment.
Second, the correlation between these for the five years for which we can make the comparison (that’s 2002-2006) is rather high.
I conclude that differential bird predation here is a major factor responsible for the decline in carbonaria frequency in Cambridge between 2001 and 2007.
So Tutt’s hypothesis stands, and is once again supported by empirical evidence.


Edited by JonF, : No reason given.

Edited by JonF, : Slight table formatting cleanup


Replies to this message:
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JonF
Member
Posts: 2831
Joined: 06-23-2003
Member Rating: 2.3


Message 281 of 346 (612342)
04-14-2011 8:05 PM


one mutation from a single ancestor causes increased melanism,
The peppered moth's dark genetic past revealed.
Replies to this message:
 Message 282 by Wounded King, posted 04-15-2011 11:45 AM JonF has not yet responded

  
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