It's not an assumption, I've worked it out. ...
... based on erroneous assumptions, as we shall see.
... First you can't maintain a species in ... a breed in artificial selection if you have any kind of increase in genetic diversity, wether through gene flow or mutation.
Because the
goal of breeding is to maintain a species all changes in phenotype, whether through gene flow or mutation are intentionally culled. That makes this a false analogy, as this process is not analogous to natural selection & mutation producing new species.
First you can't maintain a species in the wild ... if you have any kind of increase in genetic diversity, wether through gene flow or mutation.
Natural selection is not concerned with maintaining a species, it is concerned with individual surviving to breed and pass on whatever gene combinations they have, whether through gene flow or mutation. If that means evolving into a new species so be it. It is the ecology that determines the survival/breeding fitness of the population, which mean adaptation to a changing system over each generation.
So your premise 1A is invalid and cannot support a valid conclusion.
Since ... breeds ... maintain an identifiable characteristics we know that neither of these sources of increase occur, or that they are extremely rare.
Because the
goal of breeding is to maintain a species all changes in phenotype, whether through gene flow or mutation are intentionally culled. That makes this a false analogy, as this process is not analogous to natural selection & mutation producing new species.
Since ... species in the wild maintain an identifiable characteristics we know that neither of these sources of increase occur, or that they are extremely rare.
Except that they don't: there is variety within every species, and the frequency of alleles varies from generation to generation. If the ecology doesn't change then the selection will continue to be adapted to that ecology, culling out the outliers, but if the ecology changes then the focus of selection will shift towards varieties better suited to the new ecology. This has been observed.
Using a special case of apparent stasis in some populations while ignoring the documented changes in other populations means you are guilty of a logical fallacy of the part for the whole and of cherry picking only the evidence that suits your position.
So the premise 1B is also invalid and cannot support a valid conclusion. It is also distinct from premise 1A and should be listed as a second premise.
Second, if such increases do occur, ... from ... mutation, since mutation doesn't contribute much change in a short period of time ...
Actually premise 3.
This is an unsubstantiated assumption based only on your opinion and not on any facts, details, measurements or documentation.
Meanwhile we do have evidence of mutations causing speciation by polyploidy and other examples, mostly in plants, but animals are also involved.
In addition there is no requirement for evolution of a new species to occur "in a short period of time" so that means you are ignoring evolution over longer periods of time, again the logical fallacy of the part for the whole.
So the premise 2A (3) is also invalid and cannot support a valid conclusion.
Second, if such increases do occur, usually from resumed gene flow ...
While this is rare compared to actual mutational changes it is instructive to note what happens when this does occur.
When two populations are isolated from gene flow they will each accrue mutations that the other population does not have. When they rejoin these new mutations will be mixed into the general population, adding genetic diversity and you can get hybrids with some from population A and some from population B. Depending on the length of isolation, you can get (a) virtually no effect, (b)
hybrid vigor (Heterosis), (c)
Inbreeding depression - Wikipedia or (d) sterile offspring (eg mules).
There are observed cases where hybrid of such daughter population cross-breeding are more fit than either population and they then supplant the parent species.
See
EvC Forum: Population Dynamics - the math behind the evolution of species
So you have that one backwards and ignore the larger picture.
... then if a population split occurs or any other kind of selection we will again have reduced genetic diversity which always occurs when new traits form a new composite phenotype. ...
This uses your premise as a conclusion, another logical fallacy of begging the question.
This also assumes this is always the case, when evidence shows it is not. Another case of the logical fallacy of the part for the whole.
And this also assumes that a temporary situation lasts, when the evidence again is that mutations add to the gene pool.
So the premise 2B (4) is also invalid and cannot support a valid conclusion.
Selection IS the driving force of evolution and it always decreases genetic diversity.
Ignoring the role of mutation, so again this is the logical fallacy of the part for the whole.
Selection is ONE of the driving forces, mutation is ANOTHER, and the ecology is a third major driving force.
This is also a non-sequitur fallacy introducing selection in the conclusion.
So your final conclusion is not supported by your premises AND none of the premises support a valid conclusion.
Epic fail.
You have not "proved" anything but ignorance.
Enjoy
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