Summations Only

This may already have been covered by others, but it contains a couple fundamental mistakes, so I'll address it, too: First, and maybe this was just sloppy phrasing, but natural selection is not "part of reproduction". Natural selection governs which individuals of a population reproduce to pass their genes on to the next generation. Some selection factors *are* part of the reproductive process, but natural selection is defined more generally. Differential success is a common term used when describing natural selection.Ultimately the goal is to reproduce. The interplay of environment with an organism's individual qualities govern the likelihood of achieving that goal and is what is termed natural selection.Second, evolution occurs in tiny steps, not in units of species, so you cannot argue that just because no speciation occurred that no evolution occurred. Evolution isn't defined that way. The allele frequency profile of a population over time that is an accurate measure of evolutionary change over time. When and where speciation occurs, if it occurs, is a separate and often debateable issue.--Percy

Then I think you must misunderstand the premise. Natural selection influences allele frequency in a population. Changes in allele frequency over time is evolution. Most certainly the allele frequency of the moth population changed over time, so the moth population experienced evolution. This isn't a point you can debate, unless you believe the color change did not have a genetic component.--Percy

By your definition of evolution, you are correct. But you're using your own personal definition of evolution, and your definition is incorrect.The definition of evolution that everyone else in this discussion is using is the correct one. Evolution occurs in the tiny steps of microevolution that gradually accumulate into macroevolution. But the peppered moth example is not an instance of macroevolution, and no one here but you is raising any issues related to macroevolution or speciation when discussing the peppered moth.More specifically, evolution is the change over time of the allele frequency profile of a population. Environmentally influenced changes in genetically determined color in a population over time is evolution by way of natural selection.I think this discussion may have difficulty moving forward until all the participants agree on the definition of evolution.--Percy

You've said this before, and others have already noted what I'm going to say, but, as usual, I'll come at it from a slightly different direction.You appear to want higher levels of assurance than we currently have that we understand all the selection factors in moth melanism. There's nothing wrong with saying that you find the current evidence insufficient for the conclusion that differential coloration is the significant selection factor. There's no requirement that everyone's threshold of evidence be the same. But your posts make clear that you do believe that something is being selected, you just don't believe we know enough to be sure of what it is yet.So I think many are puzzled about why you are so impassioned about the peppered moth example. It's a very popular example because it is so easy for students to grasp. This example makes it very easy for students to fix the principles of natural selection and evolution in their mind. Even if evolutionists are dead wrong about the causes of moth melanism (and scientists can always be wrong), it's still a very useful example. The lesson to be taken away from this example is not about birds and moths and polution, but about important scientific principles. It enables students to gain an understanding of the principles of evolution through natural selection.What is special about the peppered moth studies is that they attempt to detect natural selection operating in the wild. As the discussion illustrates, the wild is very different from a controlled laboratory environment, and identifying and accounting for all the factors is extremely difficult. As you correctly note, perhaps there are factors at work which haven't yet been identified, but that will almost always be true outside the lab.So I think it is fine if you find the available evidence unpersuasive. There have been scientists who have felt much the same way. But that doesn't change the fact that from all the accumulated studies there *is* a lot of evidence supporting the peppered moth example. And the principle being taught by the example, natural selection, is not disputed by Creationists. What they dispute is natural selection's ability to produce sufficient change to cause speciation.--Percy

I know this was written hastily, but I still think that it captures how you're thinking about this, so it is important to correct this.We all know that science doesn't really go around proving things. There aren't "proven claims" on the one hand and "unproven claims" on the other. Proving things is the realm of mathematics, not science.Scientists use the words "proven" and "unproven" all the time, but what they really mean is "sufficiently supported by evidence to be broadly accepted" and "insufficiently supported by evidence and so not accepted."So scientists making claims about the peppered moth are not saying they are proven, but that they are sufficiently supported by evidence to achieve broad acceptance.But the way you have used the word proven when you accuse scientists of "dogmatically asserting unproven claims" implies a reckless disregard of evidence, and this just isn't true. As this thread makes clear, scientists have considered mountains of evidence in reaching their scientifically tentative conclusions. You may disagree with their conclusions, but to assert that they're "dogmatically asserting unproven claims" is just you recklessly casting about unsupported aspersions. Millikan's first attempts at finding the charge of the electron were pretty far off what we know the value to be today. Did he make a mistake? No, of course not. His work led the way toward better and better refinements of experiment and data analysis.The first measurements of the speed of light were pretty far off the mark. Would you call the measurements a mistake, or just the best that could be managed for early attempts?In the same way Ketterwell's initial studies were probably insufficiently rigorous for the claims he made. Did he make a mistake? Well, some of his experimental procedures have been called into question, but his conclusions have been largely supported by subsequent research. His initial primitive experiments provided the impetus for what eventually followed.In science, incremental progress that does not provide the final word is not a mistake.--Percy

Wise decision.--Percy

What does it mean to say that natural selection is protected against the natural world? You first argue that recessive traits only appear to be an example of natural selection, then say that changing circumstances can cause recessive traits to become more common, which is an excellent example of natural selection at work. This apparent contradiction is why your message drew the earlier responses. Also, I don't think anyone considers recessive traits to be an example of natural selection. They are what they are, and natural selection can cause their frequency in a population to rise and fall in reaction to changing circumstances. "Survival of the fittest" is just a pithy soundbite. Natural selection is more accurately described in the way you just attempted, as varying allele frequencies in a population over time in response to changing environmental pressures.--Percy

I think what you're really trying to say is that detrimental alleles that are recessive can much more easily escape selective pressures than detrimental alleles that are dominant. I don't think anyone would argue with this. While not impossible, it is extremely unlikely for recessives to never be expressed in a population, though it is possible for a rare recessive allele to disappear. Say only one member of the population possesses this rare recessive allele and he dies before producing any offspring. The recessive allele is now extinct, which is the only way natural selection can remove an allele.But say this individual reproduces. Half his offspring, on average, will carry the recessive allele, and a quarter of their offspring, and an eighth of their offspring, so on through all the generations that follow. Recessive genes propagate easily through a population, and soon many members will possess it, even though it began with just a single individual. If any two descendants of this individual who happen to possess the recessive allele should ever mate, 25% of their offspring will have two copies of the recessive gene and it will be expressed.So you can see that even if a recessive allele is present in only a single individual, unless he dies without reproducing the odds say that the recessive gene will be expressed in descendants. The recessive gene cannot hide so completely that we're unaware that it exists. (Although of course the exception would be alleles that express themselves in such subtle ways that their effect goes undetected, but that's a separate issue.) Me too. It's been plastered all over the Internet for years, including at this website.--Percy

Hi Big Al,So what about your main point? Everyone who responded is still completely puzzled as to why you're using a prime example of natural selection at work to argue that some alleles are protected against natural selection.You are correct that some parts of the genetic code *are* protected against natural selection (but not against mutation), but recessive alleles are not an example of this. A better example would be disabled genes that cannot be selected for or against because are not expressed, but the disabled gene is understood to be yet another mechanism of evolution, through further mutation and eventual re-enabling.--Percy

Most here wouldn't use this as an example of full-blown evolution either. You could use it as an example of micro-evolution, but the peppered moth is usually presented as an example of natural selection. A parenthesized "but not against mutation" is not introducing mutation into the equation.Where are you going with this, Al? What are you trying to say about the peppered moth example of natural selection?--PercyEdited by Percy, : Fix quote of self.

What on Earth has this to do with the peppered moth?--Percy

Just a few quick points:

• As the thread title makes clear (Peppered Moths and Natural Selection), this thread was originally intended to be about the evidence for natural selection stemming from research into the peppered moth.
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• But despite the original intent that the topic be natural selection, it was discovered that the origin of melanism was a mutation in recent historical times. Since evolution combines "descent with modification" with natural selection, and since mutation is "descent with modification", melanism in the peppered moth is also a demonstration of evolution in action.
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• The basis for the change in melanism to darker is a mutation to a transposon gene. Not only can the gene jump around and change it's impact, but the mutation is a very simple one and by sheer probability must recur occasionally in new individuals. In other words, the mutation would eventually arise a peppered moth populations that do not possess the mutation.
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• Analysis points to the original occurrence of the current version of the mutation happening around 1819.
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• Recent research has shown with much greater rigor, clarity and unambiguity what Kettlewell attempted to demonstrate so many years ago, the effect of melanism on selection.

--Percy