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Author Topic:   Peppered Moths and Natural Selection
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 248 of 350 (361004)
11-02-2006 10:55 PM
Reply to: Message 247 by MartinV
11-02-2006 3:23 PM


Re: More Biston betularia math. Continued. Again.
If there was strong pollution in Leeds say 1875-1975 that is 100 years and in 1875 there were no typica only Ct than the ratio CC/Ct after 100 years should be 50/1.
That (2%) is what I get for the assumption that 100% of all typica are consumed prior to reproduction.
When I assume that all male typica reproduce but all female typica are consumed prior to laying their eggs, then I get 4% (25/1).
This is still very strong predation effect.
Probability, that Ct find partner Ct to mate and subsequently express tt genotype in form of typica phenotype is very low - 1/50^2 = 0,0004.
Agreed, but this is still much lower than the percentage of typica alleles in the population - they are still being carried by the Ct moths, and IF male typica survive to breed then their chances of mating with a Ct moth increase the probability of another typica generation.
... according graph in Maths and moths after 10 years of flawless predation on typica there should be CC/Ct ratio 90%:10%, but on my computation it is only 80%:20%.
I get ~84% CC, ~15% Ct and ~1% tt - in round numbers.
Do you think, that profesor Tatum started with different preconditions?
Where you start affects it to some degree. I started with genetic equilibrium as an arbitrary point - 25% CC 50% Ct and 25% tt. The next generation was 44% CC 44% Ct and 11% tt.
He could also be assuming less than 100% consumption of both sexes.
It is however very important, because my result after 100 years will be very inaccurate ...
You should be getting an exponential decay type curve, like half-life on radioactive material.
... and whats more, it is not as strong decline of Ct population as I thought before.
It is stronger than I expected. The conclusion that I reach is that the predation does not need to be that aggressive to still have the necessary impact - perhaps the female typicas on average lay half their eggs before predation?
One could work in predation rates with different rates for males and females into the formulas .... (oh boy, what fun complications eh?) . This reintroduces Pattern {A}
Pattern {A} - male typica breeding with female typica
  • tt+tt = tt tt tt tt - all four "typica"
    0 CC out of 4 eggs
    0% CC
    0 Ct out of 4 eggs
    0% Ct
    4 tt out of 4 eggs
    100% tt
Now shown as all tt in the manner consistent with later posts, and this generates this grid:
     |  CC  |  nCt  |  rmtt |
-----------------------------
CC | C1 | nC2 | rmB1 |
-----------------------------
nCt | nC2 | n^2C3 | nrmB2 |
-----------------------------
pmtt | pmB1 | pmnB2 | pmrnA |
-----------------------------

where p and r are ratios between 0 and 1 relating to the degree of predation prior to reproduction, and this gives us (C1+2nC2+n^2C3+(p+r)mB1+(p+r)mnB2+pmrnA)/((1+n+pm)(1+n+rm)):
CC = (100%+2n50%+n^225%+(p+r)m0%+(p+r)mn0%+prmn0%)/((1+n+pm)(1+n+rm)) = (100%+n100%+n^225%)/((1+n+pm)(1+n+rm)) = CC%
Ct = (0%+2n50%+n^250%+(p+r)m100%+(p+r)mn50%+prmn0%)/((n+1)(n+m+1)) = (n100%+n^250%+(p+r)m100%+(p+r)mn50%)/((1+n+pm)(1+n+rm)) = Ct%
tt = (0%+2n0%+n^225%+(p+r)m0%+(p+r)mn50%+prm^2100%)/((n+1)(n+m+1)) = (n^225%+(p+r)mn50%+prm^2100%)/((1+n+pm)(1+n+rm)) = tt%
With these formulas and with p=1.0 (full male survival until reproduced) and r=0.5 (half female egg laying completed prior to predation) I get:
after 10 years = 54.1% CC: 38.9% Ct: 7.0% tt
after 100 years = 92.0% CC: 7.8% Ct: 0.2% tt
This still gives a very strong result of typica predation after 100 years that would be consistent with the data from the studies, even though only 1/4 of the typica moths are consumed prior to reproduction.
And this still has typica alleles within the population to allow reversal without needing to assume immigration into the polluted areas.
I can go further and assume there is only 10% predation on typica moths due to preferential predation and I get:
after 10 years = 37.5% CC: 47.5% Ct: 15.0% tt
after 100 years = 81.0% CC: 18.0% Ct: 1.0% tt
With subsequent predation of typica after reproductive success, this could still give a result of typica predation after 100 years that would be consistent with the data from the studies, even though only 10% of the typica moths are consumed prior to reproduction.
The other option is to assume immigration into the area to replace lost t alleles. You could assume that males fly further to mate and so would disperse across {pollution\non-pollution} boundaries.
They would not have to reach far, as if we assume 1 mile a year then in 10 years the population 10 miles from non-polluted areas would be mixing local population with the gene flow population that has 84% CC: 15% Ct: 1% tt assuming total predation.
If we use 100 years for the age of the local population, then I get a local population proportion of 98% CC: 2% Ct: ~0% tt and averaging those, I get 92% CC: 8.5% Ct: 0.5% tt.
In any case we still see that the t alleles are depressed by preferential predation and that this causes a decrease in t alleles and an increase in C alleles.
This change is still basic evolutionary natural selection due to preferential predation of moths by birds.
All this change in predation rates and gene flow rates accomplishes is to help explain the recovery of typica moths in a relatively short period after the pollution was cleaned up and preferential predation focused back on the carbonaria variety moths instead of the typica ones.
The mechanism of change is still preferential bird predation first on carbonaria (before pollution) then on typica (during pollution) and then on carbonaria (after pollution).
Natural Selection.
Enjoy.

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This message is a reply to:
 Message 247 by MartinV, posted 11-02-2006 3:23 PM MartinV has replied

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


Message 255 of 350 (362258)
11-06-2006 8:44 PM
Reply to: Message 254 by Admin
11-05-2006 4:40 PM


Re: Too-long lines problem fixed
was it one of the formulas? I never saw it so don't know what you had to change.

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


Message 257 of 350 (362281)
11-06-2006 9:52 PM
Reply to: Message 249 by MartinV
11-05-2006 11:48 AM


Back around again ... this has already been covered, eh?
Typica alleles should have been created by mutation during industrialization. I would like see if the pollution would have made green or blue sooths, it there would be also mutation in this color.
No mutation was involved in the natural selection of one variety of already existing moth over the other variety of already existing moth.
Environment does not cause mutations to match the environment.
But then ratio between heterozygotes without any selective predation after 100 years will be 1:0,36
Without selective predation pressure, the genetic equilibrium would be 25% homozygous carbonaria, 50% heterozygous carbonaria, and 25% homozygous typica, with 50% carbonaria alleles and 50% typica alleles.
With selective predation on typica varieties, the ratio of homozygous carbonaria to heterozygous carbonaria depends on a lot of factors that are not documented, including proportion consumed prior to reproductive success and on gene flow between adjacent populations always importing heterozygous moths into areas with depleted typica alleles (like water flowing downhill).
After 100 years\generations, it can easily vary from (37.1%/84.7=43.8% homozygous carbonaria) / (47.6%/84.7=56.2% heterozygous carbonaria) when only 1% of typica are consumed prior to reproductive success (with remaining 14.3% typica consumed after) ...
... to (96% homozygous carbonaria)/(4% heterozygous carbonaria) when 50% of typica moths are consumed prior to reproductive success.
The cause for the absence of typica moths from the samples collected is preferential predation by birds.
The cause for the shift in proportions of typica alleles from 50% of the population in one without any preferential predation pressure to either of those levels above is preferential predation by birds.
And we do not know when and where mating occurs and how are selection effective before/after mating.
And this really doesn't matter for us to know that (a) the cause for the absence of typica moths from the samples collected is preferential predation by birds, and (b) the cause for the shift in proportions of typica alleles from 50% of the population for one without any preferential predation pressure to either of those levels above is preferential predation by birds.
In any case selective predation seems to have no dramatic influence as to the typica, while it recovers own population in short time after change of environment, so selection seems to be incapable to reverse population into typica and vice versa.
Yes, changing from 99% typica 1% carbonaria to 1% typica 99% carbonaria and then from 1% typica 99% carbonaria to 99% typica 1% carbonaria is not dramatic at all.
Again, the genetic equilibrium population proportions in the absence of any preferential selective mechanism is 25% homozygous carbonaria, 50% heterozygous carbonaria, and 25% homozygous typica, so any population that is NOT at those levels is being subject to preferential selection = preferential predation by birds in this case.
The recovery of typica variety to 25% of the population is all that can happen without the assistance of preferential predation -- no matter how many generations it takes, no matter what reservoir the typica alleles come from.
How rapid the recovery is initiated is a matter of how much typica alleles were still existing in the reproductive reservoir of the populations, ...
... and with the possibility of non-polluted populations moving into non-polluted environments the apparent recovery rate can be higher ...
... but the final result - typica variety moths at ~99% of the post-pollution population - is still due to preferential predation of (now) carbonaria variety moths by birds.
No matter how you slice the data, preferential predation plays a significant role in the observed proportions of typica and carbonaria moths in pre-industrial, industrial polluted and post industrial polluted areas.
In any case neodarwinism as to the selection would be right, no?
Those best able to survive and reproduce pass their genes to the next generation. That is all natural selection does - distinguish between those BETTER able to survive and reproduce and those LESS able to survive and reproduce. It does not matter WHAT that fitness feature is, just that it be existing within the population under selection pressure.
Yet mechanism of hidden alleles which were previously succesfull in heteroyzgotes seems to me be very good device how not to react headless to change of environment.
The genes don't even need to be that "hidden" - it depends on the degree of selection pressure involved: if only 1% were consumed prior to reproductive success there is still an effect on the population, and you would still have 15.3% of the preferential predation consumed typica moths in a generation after 100 years\generations. This is a drop from 25% for genetic equilibrium, or 60% of the equilibrium value: this is still natural selection.
Natural selection only needs SOME proportion of the population to be preferentially selected for it to have an effect on the proportions of alleles within the overall population/
Enjoy.

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This message is a reply to:
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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 260 of 350 (362592)
11-08-2006 8:03 AM
Reply to: Message 258 by JohnnyHads
11-08-2006 2:16 AM


Re: So wait a minute here ... what, for someone who didn't read the thread?
Welcome to the fray JohnnyHads
Is the original post claiming that if the population of moths becomes mainly black, or mainly white because of natural selection (survival of the fittest) that its an example of evolution??
The OP clearly states that this is an example of natural selection. Natural selection is a part of evolution, but does not include all of the mechanisms involved.
Did the white moth cohabit with the black moth before the population changes due to the industrial revolution?
Yes, they were previously existing varieties of the moths, with the carbonaria (that's "black" for you, although "dark" is much more accurate) in much smaller proportions than typica (that's "white" for you, although "light" is much more accurate).
Natural selection operates on existing variations within a population, letting those better able to survive to live and pass on their genetic patterns to the next generation.
... or I AM getting the point and its author is ignorant and brainwahsed for someones personal agenda.
LOL. Nothing like starting your career here with an open ad hominum insult that is in violation of the board rules.
Surely black moth > white moth isnt evolution in any educated persons mind.
moth = moth
Can this moth create a non moth?
Speciation is evolution, and it has been observed. Species will always be members of whatever group their ancestors were members of.
Creating something unrelated from one species or another is an ignorant creationist straw man argument and has nothing to do with the theories of evolution.
If so, questions must be asked to help the ignorant find common sense.
Ask away, and we'll be happy to help.
Or you could start by reading the entire thread first, then go back and ask questions on parts you still don't understand.
Enjoy
ps type [qs]quote boxes are easy[/qs] and it becomes:
quote boxes are easy

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This message is a reply to:
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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 270 of 350 (438320)
12-03-2007 10:40 PM
Reply to: Message 269 by MartinV
12-03-2007 12:26 PM


Re: PPT file and data now available
I suppose industrial revolution didn't polute whole areas from one day to another. It took some time. So melanica having less places to rest moved to less poluted places. ... Natural selection has nothing to do with it - melanica perhaps just relocated to clean areas.
Even IF you were right about emigration, you would still be wrong about natural selection, for that would have caused the emigration -- the movement of the moths in response to the changing environment would have selected for their survival.
But you are also wrong (as usual) about the preferential selection by bird predation NOT being involved, documented, verified, replicated.
Enjoy.

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This message is a reply to:
 Message 269 by MartinV, posted 12-03-2007 12:26 PM MartinV has replied

Replies to this message:
 Message 271 by MartinV, posted 12-04-2007 3:41 PM RAZD has replied

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


Message 272 of 350 (438449)
12-04-2007 6:14 PM
Reply to: Message 271 by MartinV
12-04-2007 3:41 PM


MartinV continues to ignore reality and evidence - same old same old
And science, life, reality and the peppered moths are still all singularly unimpressed by your opinion and lack of understanding.
(Much ado about nothing)
That's you in a nutshell. Because emigration does not explain why the populations change and stay changed while the discoloration exists without the pollution.
Nor does it explain the documented differential bird predation. You have to ignore the reality of evidence to reach your conclusions, and that is not science.
Enjoy.

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This message is a reply to:
 Message 271 by MartinV, posted 12-04-2007 3:41 PM MartinV has replied

Replies to this message:
 Message 273 by MartinV, posted 12-05-2007 1:39 PM RAZD has replied

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


Message 274 of 350 (438616)
12-05-2007 2:07 PM
Reply to: Message 273 by MartinV
12-05-2007 1:39 PM


MartinV ignores the rest of the evidence that shows he is irrelevant. As usual.
This factoid would be relevant if (1) it made the moths rest in places they normally don't (it did not) and (2) no other study had validated this result (and everyone that has attempted to replicate this basic study - with or without car radiators - has resulted in the same net observation of preferential predation).
Conclusion: both the factoid and your opinion are irrelevant to the real world.
Logically one would review the published literature (which here would include the facts already posted) to make sure that what one was saying wasn't already refuted, but you have never done this. Therefore I conclude you are not interested in facts and reality.
For instance, if one wanted to know where the moths normally rested they could read Message 265, and if one wanted to know if the preferential predation experiment had been run and validated they could also read Message 265. Ignoring these facts does not make an argument, it just demonstrates ignorance.
Enjoy.
Edited by RAZD, : end

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This message is a reply to:
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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 277 of 350 (439366)
12-08-2007 1:36 PM
Reply to: Message 276 by MartinV
12-08-2007 1:27 PM


falsehoods recycled
Edited by RAZD, : not worth responding. it feeds the troll
Edited by RAZD, : Nor am I worried that the threat of consequences logical fallacy will deter rational people from making decisions based on the ample evidence in this thread - regardless of whether I respond to MartinV or not.

This message is a reply to:
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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 313 of 350 (670708)
08-17-2012 1:11 PM
Reply to: Message 305 by Big_Al35
08-16-2012 8:49 AM


Natural selection is ...
Hi BIg_Al35,
Natural selection, rather than being defined as "survival of the fittest" might be better viewed as "allele domination under significant environmental and sexual selection pressures".
"Survival of the fittest" is not accurate, it is more "[i]genetic trait survival in those individuals able to live long enough to breed" ... if an organism survives long enough to breed then it is successful in passing its genes.
It would appear that the peppered moths are a good example of how natural selection (as currently defined) is protected against in the natural world.
There is no protection against the natural world - and organism survives to breed or it doesn't. Only the genes in the survivors persist to breed the next generation.
Note that natural selection is not the only mechanism that can remove non-beneficial traits from a gene pool, you can also have stochastic (chance) occurrences, like volcano eruptions, that can wipe out all copies of a specific gene (as well as many individuals without it) in a breeding population. This is called neutral selection, because it isn't related to any traits. It can also remove beneficial traits in a population.
The process of evolution involves the change in the frequency distribution and composition of hereditary traits within breeding populations from generation to generation, in response to ecological challenges and opportunities.
This is sometimes called microevolution, however this is the process through which all species evolve and all evolution occurs at the breeding population level.
Mutation can cause change in the composition of hereditary traits carried by individuals of a breeding population, but not all mutations do so. In addition there are many different kinds of mutations and they have different effects (from small to large).
Natural Selection and Neutral Drift can cause change in the distribution of hereditary traits within the breeding population, but they are not the only mechanism that does so.
The ecological challenges and opportunities change when the environment changes, the breeding population evolves, other organisms within the ecology evolve, migrations change the mixture of organisms within the ecology, or a breeding population migrates into a new ecology. These changes can result in different survival and reproductive challenges and opportunities, affecting selection pressure, perhaps causing speciation, perhaps causing extinction.
Mutations of hereditary traits have been observed to occur, and thus this aspect of evolution is an observed, known objective fact, rather than an untested hypothesis.
Natural selection and neutral drift have been observed to occur, along with the observed alteration in the distribution of hereditary traits within breeding populations, and thus this aspect of evolution is an observed, known objective fact, and not an untested hypothesis.
The Peppered moths are one of the examples where natural selection has been observed to occur.
Darker and lighter moths are simply varieties in the available DNA pool ...
This much is correct, and the differences between them account for the shift in their frequency between the two different ecologies, one that selected for dark moths and one that selected for light moths.
... and other alleles can exhibit recessive or dominant traits as demonstrated in experiments by Mendel.
Mendel's experiments dealt with how alleles existing in a population are inherited, with varied effect on individuals due to dominance\recessiveness, and had nothing to do with natural selection -- there was no selection pressure in his experiments.
He also did not know about mutations and how they could introduce new traits or alter existing ones. He did have some slight variation in his experiments where the "Mendel Laws of Inheritance" did not always work. These show up in his statistics. They are, of course, due to mutations in the populations.
Recessive traits which are only exhibited when set criteria are met ... when the circumstances change and become favourable these traits will be manifested again.
Biological reproduction does not happen that way. The expression of different traits in the population via reproduction generally follow the Mendelian principles, they are NOT a response mechanism. IF expressed (ie gg instead of GG, Gg or gG) THEN they are available for selection pressure to act on their expressed traits. Natural selection then determines if the homogeneous recessive can survive to breed or not.
Edited by RAZD, : .

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


Message 315 of 350 (670711)
08-17-2012 1:27 PM
Reply to: Message 314 by Big_Al35
08-17-2012 1:14 PM


Sickle Cell mutation and Natural Selection -- new topic?
Hi again Big_Al35,
... If the environment was so harsh that a particular trait could not even survive long enough to reproduce, then only individuals who are actively expressing that trait would disappear. The unexpressed allele would still linger on in the population at large. These harsh conditions could even continue for thousands or millions of years. In every generation where the allele is expressed, the individual would die.
However, after enough time had passed, circumstances or the environment might change. Individuals who are now expressing the gene may actually survive or even flourish. The example that I am thinking of is the peppered moths.
A better example for you is sickle cell anemia
Sickle cell disease - Wikipedia
Carrying both copies is usually fatal, carrying one copy is beneficial in an ecology with malaria, where carrying no copies can be fatal.
This is not the case with the peppered moths -- would you like to start a new thread on tht topic (Sickle Cell mutation and Natural Selection)? Then we can discuss how a mutation can change a trait in an individual and then how that trait ca survive in a breeding population.
I suggest a new thread as this one should be near or in summation mode.
Enjoy

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This message is a reply to:
 Message 314 by Big_Al35, posted 08-17-2012 1:14 PM Big_Al35 has replied

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


Message 321 of 350 (670730)
08-17-2012 7:36 PM
Reply to: Message 320 by Percy
08-17-2012 6:03 PM


so is it summary time?
if anyone wants, I'll be happy to start a thread on sickle-cell and natural selection.
or perhaps one on "protection" of unexpressed genes from natural selection
Enjoy
Edited by RAZD, : .

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


Message 323 of 350 (670742)
08-18-2012 5:58 AM
Reply to: Message 322 by pandion
08-18-2012 1:48 AM


new topic? current topic drift? current topic summary mode?
Hi pandion,
I note two things:
(1) the topic is starting to drift away from peppered moths as an example of natural selection into a general discussion of natural selection, and
(2) the topic is at the point where admins usually instigate summary mode posting.
I would like to see this discussion continue, but feel that this really should be a new topic, especially as it might go long and might need many baby steps to explain individual points.
As noted, mutation is one of the sources of genetic diversity upon which natural selection acts. Mutation and natural selection are but 2 of the 9 recognized mechanisms of evolution. Would you like to learn about them?
9 recognized mechanisms of evolution would be a great new topic.
Enjoy
abe: or if you want, you could join me (or im me to discuss) on Introduction to Evolution
Edited by RAZD, : ps

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RAZD
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Posts: 20714
From: the other end of the sidewalk
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(2)
Message 331 of 350 (670810)
08-19-2012 2:19 PM
Reply to: Message 327 by Big_Al35
08-19-2012 10:22 AM


once more around the bend ...
Hi Big_Al35
... Two or more types of moth (namely dark and light existed prior to the event ie industrialization) and two or more types existed after the event. It was simply a case of which type of moth flourished when.
Therefore I wouldn't view this is as an example of evolution. Others might disagree.
You and some others here have introduced mutation into the equation. This may account for genuine micro-evolution but has nothing to do with the example I was discussing.
Let me see if this helps:
The diagram is simplified, as breeding variations can exist through several generations (being due to existing mutations plus new mutations), as is the case with the peppered moths such that some with less the favorable camouflage still survive to breed in either ecological condition.
Therefore I wouldn't view this is as an example of evolution. Others might disagree.
Correct:
Evolution involves a full cycle of the loop, so no, natural selection alone is not and example of evolution per se. This is a common creationist mistake: when you walk you don't only use one leg, but alternate from one to the other, and the cycle of evolution is a similar process.
Micro-evolution is evolution within breeding populations. Macro-evolution is the continued evolution of populations looked over many generation cycles and many breeding populations of the same species. There is no difference in the mechanisms involved other than time scale and the focus of the observation (the occurrence of variations versus the accumulation of variations).
If you want to discuss micro vs macro, I suggest another thread as that will definitely be off topic on this thread that is about part of (micro) evolution. see MACROevolution vs MICROevolution - what is it? for example (note you will need to define what YOU think they are in order to form a basis for discussion). You may also want to read Introduction to Evolution (still a proposed topic so not open for comments).
... Two or more types of moth (namely dark and light existed prior to the event ie industrialization) and two or more types existed after the event. It was simply a case of which type of moth flourished when.
Exactly:
  • prior to the industrialization the population consisted of two variations within a species, with breeding and gene flow between the varieties (because varieties are a division below species due to interbreeding), with a higher proportion of light (say 80%) than dark (20%)
  • during the industrialization event the proportion shifted to higher proportion of dark (say 80%) than light (20%) due to the change in advantage of dark camouflage on dark ecologies from and advantage of light camouflage on light ecologies -- and
  • when the industrialization event ended and the ecology switched back so did the proportions of light and dark moths.
This is because the ecologies in either case did not prevent the less advantaged camouflage group to survive at a low level so they were not all killed and eaten.
Natural selection does not necessarily involve wiping out one variety in favor of another, but in changing the proportion of the different varieties that survive to breed (lower right box). The frequencies of the different hereditary traits change.
Enjoy

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This message is a reply to:
 Message 327 by Big_Al35, posted 08-19-2012 10:22 AM Big_Al35 has not replied

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


Message 335 of 350 (670831)
08-20-2012 6:44 AM
Reply to: Message 333 by Big_Al35
08-20-2012 4:21 AM


a few more new topic ideas
Hi again Big_Al35,
Actually, now that we covered the fact that some traits are offered a degree of protection from extinction ...
What we've covered is that during an ecological change of short duration there is an observable shift in the frequency of hereditary traits to adapt to the new challenges and opportunities presented by the change.
Initially this change is not enough to eliminate the less fit camouflage from the gene pool, so when the ecology shifts back the previous (Mendelian) pattern can also reappear.
This change is likely to be along an exponential curve as time passes (nature loves exponential curves it seems, almost as much as beetles ... ), so the longer the change persists the more likely the less fit camouflage will not be able to survive to breed and be culled from the gene pool.
... by being recessive, ...
You still need to understand the difference between change in DNA through mutation, with subsequent dispersal in the gene pool, and gene mixing of existing traits via Mendelian mechanisms. It isn't always the recessive gene that is being repressed in the changing ecology.
A recessive gene may have some protection and it may not -- that depends on the degree of selection pressure and the length of time involved (the exponential curve would be drawn out a little longer before the trait is culled).
A new topic on natural selection and new mutations vs Mendelian gene mixing might help.
There is also the issue of how a recessive gene becomes a dominant gene in the gene pool and whether a new mutation is dominant or recessive (or just neutral), that could be discussed on that new topic: it should be fairly simple to understand that if a change in the ecology suppresses and then culls the dominant gene, that the recessive gene becomes the dominant gene, then a new mutation, that starts out neutral can become expressed and be recessive in a new ecology that over time this pattern will result in permanent changes to the mixture of traits available in the gene pool and the existing population can have an entirely different set of genes from the ancestors.
Maybe I'll work on one for you if you are interested.
.... maybe someone ought to cover why large chunks of dna, particularly the genes, are largely protected from mutation events.
Another great idea for a new topic.
Enjoy.
Edited by RAZD, : added

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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This message is a reply to:
 Message 333 by Big_Al35, posted 08-20-2012 4:21 AM Big_Al35 has not replied

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


Message 340 of 350 (670910)
08-20-2012 11:58 PM
Reply to: Message 338 by barnes
08-20-2012 6:31 PM


non sequitur post not on topic
Hi barnes and welcome to the fray,
I’m sure we can all agree life is more complex than a 350 Chevy engine ...
One of the things this forum likes to do is confine threads to specific topics, in this case the role that natural selection plays in the changes observed in the peppered moth populations.
... and rebuild it in to a Duramax diesel the hole time never missing a beat. You boys get that one done and we can talk
A variation on the old airplane in a junkyard PRATT (point refuted a thousand times).
Why don't you start a new thread on just this little concept, and we will be glad to show you what is wrong with it. It is off topic on this thread.
Go to Proposed New Topics to post new topics, if you are serious about discussing it, or just post it in Coffee House if you want to see what happens.
Enjoy.
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we are limited in our ability to understand
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Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 338 by barnes, posted 08-20-2012 6:31 PM barnes has not replied

  
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