Faith writes:
I know that, but if they are being selected and mutation is continuing to add to the gene pool you aren't getting a delineated recognizable species such as we see IN REALITY both in the wild and in breeding.
On the contrary, it's precisely what we see in reality. Almost every newly born organism possesses new mutations. The average human being possesses around 100 new mutations. Research has told us the mutation rate for many types of life, you can read about it over at the
Wikipedia article on Mutation Rate.
Despite all these new mutations flowing into species population the world over, what you called "delineated recognizable species" continue to exist. That's because mutations, at least those that yield viable offspring, cause only tiny changes, and many are neutral.
Species are not eternal forms persisting forever. Species are plastic and change over time. As environments change species gradually change to adapt. Even when environments are constant species still change due to the genetic drift that is a result of the imperfect copying of reproduction that introduces new mutations.
This is all just some abstract idea that has nothing to do with what really happens.
It would be incorrect to say that this is only what we theorize might happen. It is precisely what we know happens because research has revealed it happening. We know that reproduction is almost always imperfect and causes mutations because there have been studies of life ranging from bacteria to mammals that reveal these mutations occurring. And we know the effects of mutations that create viable offspring are tiny. And we know that despite this species remain the same species over many, many generations. It probably takes at least 10,000 generations to produce a new species under normal circumstances.
I don't know what you would get in this scenario but it's something blurry and constantly changing,...
Yes, you're right. In reality species boundaries can be blurry, as illustrated by ring species that blend into each other at the boundaries of their territories. And yes, species are constantly changing, too, though not on human timescales.
That species boundaries can be blurry is responsible for the
species definition problem. While we have no problem telling that cats and dogs are different species, its much more difficult when determining whether wolves and dogs are different species, or whether gray squirrels and red squirrels are different species. Biologists use a variety of methods to determine whether two phenotypically very similar species are the actually same species, but the most common is genetic analysis.
... NOT an identifiable new species which is what happens IN REALITY.
Any breeding population of organisms is an identifiable species, regardless of the particular qualities of the species.
(You can't take the analogy much further - it was intended only as an illustration of how diversity is being added and taken away at the same time through the simultaneous processes of mutation and seleciton.)
See above. This is all theory gone bonkers, it has nothing to do with reality.
No, it's not theory, it's reality. There is nothing that can stop the imperfect copying of reproduction that results in mutations, and environments are constantly imposing selective pressures on populations. All species populations are always simultaneously experiencing both mutation and selection. There's is no possible way to prevent either from occurring.
But to GET that new species the traits have to be SELECTED AND ISOLATED.
Without mutation you cannot get a new species. You can, for example, select for domesticity in wolves and foxes and find that other traits, such as curled tails, emerge at the same time, but neither domesticity nor curled tails are new traits. Rather, they were already present in the parent population but to only a tiny degree, and breeding develops and emphasizes these traits. But dogs and tame foxes can still breed with the original wolves and foxes because they are still the same species. Isolation and selection alone does not create new species. If it did then breeders would be creating new species all the time.
And THAT happens only when all the alleles for OTHER traits are suppressed, reduced, or eliminated = REDUCED GENETIC DIVERSITY REQUIRED TO FORM A NEW SPECIES.
Then why can't breeders create new species?
So? Should happen a lot in my scenario that you get new "species" from new mixes of old alleles.
No, it should not happen that a new species emerges by "new mixes of old alleles". If a subpopulation has all the same genes and alleles of the original population then these populations can still interbreed and are still the same species.
Plus your approach will never yield what we actually see in nature, which is that only very, very similar species have the same genes. Any species whose differences are more than slight will have different genes and alleles. Your conception will never produce different genes between species, which is precisely what we see in nature.
What we should see in nature were your view correct is a species heredity chart like this where the parent population has all the genes and alleles of all the daughter and grand-daughter populations while the daughter populations have only subsets of the parent's genes and alleles. And the grand-daughter populations should have subsets of the daughter populations' genes and alleles:
[face=Lucida Console] parent pop
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daughter pop 1 daughter pop 2
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------------------------------- -------------------------------
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daughter pop 1a daughter pop 1b daughter pop 2a daughter pop 2b[/face]
What you need to find in order to have evidence that your scenario is something that actually happens is to find that every gene and allele in the daughter populations is already present in the parent population. And you need to find that every gene and allele in the granddaughter populations is already present in the daughter and parent populations.
But something like this has never been found, not in nature and not in breeding programs.
If the only way to get a ceramic pot out of a hunk of clay is to pare away all the stuff that doesn't look like the ceramic pot, you aren't going to get the ceramic pot if you carve a little then add a little clay somewhere else and so on. Carve and add carve and add, no, that is not how it works in reality.
No, that's pretty much how it works in reality, except for the part about having the specific goal of a ceramic pot. Evolution has no specific goals, just the general goal of adaptation to the environment.
What you guys seem not to appreciate is that the existing alleles and genes in a genetically diverse population are more than sufficient to form many many subspecies through selection and isolation of portions of the gene pool.
Of course we understand that one can form many subspecies from a single set of genes and alleles. But one cannot form a new species unless one has a supply of new genes and alleles.
Main populations are evolving, too, and possibly at a faster rate since they can draw upon a much larger inflow of new mutations.
NOT UNLESS THERE IS SELECTION.
I think you must be operating under the misimpression that main populations do not undergo selection. That would be incorrect. The processes of mutation and selection are always in operation in all populations everywhere.
The new combinations are brought about by the change in gene frequencies brought about by the reproductive isolation of a reduced number of individuals, making for a new gene pool of interbreeding individuals, and that's how new breeds, varieties, species come about. The new combinations are powerful sources of new traits. You do not need mutations.
This would be incorrect. A subpopulation with all the same genes and a subset of the alleles will still be the same species. It will still be able to interbreed with the main population. You cannot create a new species without new genes and alleles.
Of course selection operates upon mutation. Always, constantly, all the time. How could it not? Selection operates on all expressed parts of the genome, whether newly arisen through mutation or part of the original genome.
You must be using the term "selection" in some other sense than I am. Selection is something that happens at the population level as I am using it.
What I said is true of both individuals and populations. Let me say it again in terms that are specific to a population. Selection operates continuously upon all expressed portions of the gene pool of a population, including newly expressed portions due to mutation.
That mutation and selection are always active is why both faucet and drain were open at the same time in the bathtub analogy.
Sounds plausible in the abstract but in reality it's not what happens, it does not describe what really occurs.
Again, we think this is what occurs in reality because when we looked at reality this is what we observed happening. We observed that almost all reproductive events include a small number of mutations. We observed that the environment is always exerting selection pressures on populations.
--Percy
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