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.
Darker and lighter moths are simply varieties in the available DNA pool and other alleles can exhibit recessive or dominant traits as demonstrated in experiments by Mendel.
Recessive traits which are only exhibited when set criteria are met are nevertheless still available in the DNA source. It might appear as though they have been selected against by observers and a good argument for natural selection. However, when the circumstances change and become favourable these traits will be manifested again. Mendels examples include the return of green and wrinkly recessive traits in subsequent generations.
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".
Are you suggesting that individual moths are changing their appearance in response to the environmental changes?
I think your comprehension skills are somewhat lacking. Try re-reading my post.
If instead you are suggesting that the ability to produce a dark (or light colored) moth is present in the population, but is recessive, then you are not expressing an issue with natural selection which is merely a screening process, but with mutation which is a source of diversity.
I have supplied you with two definitions for natural selection. An old darwinian definition "survival of the fittest" and another which I have conjured up myself. I am totally bemused as to how you have chosen to define natural selection, as "screening process" doesn't really tell me anything. Perhaps you would be kind enough to offer your own definition.
And as for mutation, I didn't even mention mutation once in my post. Does mutation have anything to do with this topic?
What does it mean to say that natural selection is protected against the natural world?
Populations and species are protected from the harsh dangers of natural selection. Mendels laws of heridity provide a degree of protection. Where we might believe that certain traits have been wiped of the face of the earth through "survival of the fittest", those attributes can live on, hidden and preserved, within the genome. When more favourable circumstances arise, those traits will re-emerge continuing to offer variety where it appeared lost.
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.
I am glad that we can "kind of" agree on this more modern definition of natural selection.
A recessive gene can't "hide" simply by dint of it being recessive. If two carriers of the recessive gene mate and produce offspring, it will be expressed.
Let's use your definition ie "survival of the just good enough". 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.
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.
Not exactly, some alleles can be both dominant and recessive. Let's say we had alleles A, B and C. A might be dominant to B but recessive to C. B is recessive to A but dominant to C. And C is dominant to A but recessive to B. This might allow A, B and C to be bulletproof from being selected out of the gene pool.
Natural selection is the differential reproductive success of organisms that possess benificial genetic traits (that lend a reproductive advantage).
Classic evolutionary tautology. The reproductive success of organisms that have traits which promote reproductive success. The reason this is nonsense is because it contains no information. Reproductive success (not quantified) used twice and traits (quantified only by reproductive success which remains undefined).
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.
I think everyone accepts that natural selection occurs but it's the nature of natural selection and the sequence of events that we are discussing here. I have used the example of the peppered moths. 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.
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.
Actually, now that we covered the fact that some traits are offered a degree of protection from extinction by being recessive, maybe someone ought to cover why large chunks of dna, particularly the genes, are largely protected from mutation events.