Saturday, March 10, 2012

Speciation + Evolution = LOTS of Trait Diversity with LOSS of Genetic Diversity leading to end of ability to evolve

Another one from RAZD at EvC, Speciation + Evolution = More Diversity
The scene: sitting at computers all over the world ...
"Why don't creationists understand evolution -- it is so simple," the evolutionist wails:

1. Evolution - the change in hereditary traits in populations from generation to generation - is an observed and documented fact, a process that occurs constantly in the natural world around us, and

2. Speciation - the division of parent populations into reproductively isolated daughter populations - is also an observed and documented fact, a process that occurs frequently in the natural world around us.
These two simple processes are sufficient to explain the diversity of life we know, from the world around us, from history, from prehistory and archeology, from geology and physics and paleontology and the fossil record, and from chemistry and the genetic record.
Well, it sounds good on paper, I guess, as theory at least, but unfortunately it fails in reality. Yes, there is an "evolution" by which heritable traits change from generation to generation, but this has never been observed beyond what we call "micro" evolution, or evolution within the genetic limits that define each species, and in fact it can't occur beyond microevolution for the reasons I've given over and over here, which are the same reasons there is no evolution beyond speciation. And yes, speciation is also a documentable fact, but it always occurs with loss of genetic diversity, even to the extreme of fixed loci or total homozygosity for some traits in the population, which makes further evolution beyond speciation purely a pipe dream.

But RAZD just goes on asserting the theory, the pipe dream, as if it were reality, as they all do.
We can even see how evolution causes speciation with Ring Species:

1. the species forms a band made up of several varieties around some barrier to their survival ability,

2. each of the varieties has slightly different hereditary traits from their neighbors,

3. each reproduces with their neighbors in hybrid zones that show a mixing of the hereditary traits of the two neighbors, except that

4. when they meet on the other side of the barrier, the two ends do not mate.

Evolution results in different hereditary traits developing in each of the areas dominated by the different varieties, differences that do not hinder mating until they reach a certain threshold - the difference between the end varieties.

Yes, pretty much but as long as he sticks to the level of traits -- of the phenotypes, of the different observable characteristics between the populations -- he misses the reason what happens happens: The splitting of the populations changes the gene frequencies. When new traits emerge this is because alleles for competing traits have been reduced which can proceed after many population splits to the point that they are completely lost to the new population. After a series of splits the genetic diversity may be quite drastically reduced, and the main reason there is no interbreeding between the first and last populations is the genetic incompatibility that has developed by then.

Again, my prediction is that if you sampled the DNA of the first and last populations (better done in a laboratory where you can sample the first before it too undergoes change), you should find much greater genetic diversity in the first and much reduced diversity in the last, more heterozygosity in the first, more homozygosity in the last, particularly for the traits that are most characteristic of the populations.
Remove any one of the intermediate varieties, so that the band is broken, and you have two distinct species.
We now have more species than before, so life is more diverse. It is so simple:

Evolution + Speciation = Diversity
Way TOO simple, RAZD. Yes you do have more diversity of TRAITS, but you are simultaneously getting REDUCED diversity of GENETIC POSSIBILITIES. This is all just the usual evolutionist daydream based on surface facts completely ignoring what is going on genetically, which is the NECESSARY reduction of genetic diversity, which occurs with EACH splitting off of a portion of the population to form a new population. This is a trend that can keep producing new phenotypes for some time by losing more alleles, but can ultimately arrive at such genetic depletion that no further phenotypic change is possible, a condition like that of the cheetah. Not that this degree of depletion is inevitable, but reduction in that direction certainly is.
This little scenario depicts, I believe, the state of many debates between creationists - people that predominantly use faith to understand the world - and "evolutionists" - people that predominantly use science to understand the world.
What "this little scenario" actually depicts is evolutionist reliance on wishful thinking as they spell out what they THINK happens, because they haven't really faced the GENETIC PICTURE which is working against their all-too-sanguine expectation that change in traits can just go on and on without genetic cost. It really is a daydream, a fantasy. And it's quite the joke that they are constantly claiming to appeal to EVIDENCE and accusing creationists of relying only on faith.

(I skipped his caricature of the creationist response to the above because it is a distraction from what I'm trying to say here.)
Where does "large" change come from? - the change that makes giraffes so different from kangaroos? Simple:

Speciation - the division of parent populations into reproductively isolated daughter populations - is also an observed and documented fact, a process that occurs frequently in the natural world around us, and

Evolution- the change in hereditary traits in populations from generation to generation - is an observed and documented fact, a process that occurs constantly in the natural world around us.
SO simple as long as he just goes on daydreaming about the surface traits and imagining that there are no limits to change.
Speciation + Evolution = More Diversity
After speciation has occurred, the daughter populations no longer share genes through reproduction, and they are free to evolve completely different traits.
Yes, and this lack of sharing of genes means a LOSS OF GENETIC DIVERSITY. Yes, they ARE "free to evolve copletely different traits" but this is ALWAYS made possible by the loss of competing alleles for those traits, which is completely ignored by evolutionists. You can always get new traits BY LOSING competing alleles, but if the population splits that bring this about continue to occur, eventually a point will be reached where you can't get new traits any more because you'll be completely out of alleles. Speciation may not always mean genetic depletion but it certainly means genetic reduction from earlier populations particularly where the main new traits are emerging.
The likelyhood is high that one of them will become quite different, either to inhabit a new ecology that the other is not as well suited to (could have caused the original split), or to make use of the existing ecology in a different way, and this will lessen competition between the two species rather than drive one to extinction.
Lotta sheer conjecture there. It really isn't even necessary to posit environmental or situational reasons for trait changes or even the population splits themselves. Migration will bring about splits and the splits alone will bring about trait changes. The fewer individuals at the start of a new population the bigger the observable trait changes, the ecology is not likely to have much to do with it. It may be that both populations still have sufficient genetic variability even to undergo several further splits if necessary, but since he's completely ignored the whole question of what happens to the genes while focusing on the traits and fantasizing endless change he's going to miss the state of genetic depletion also when it does finally occur after more population splits.
Continued evolution of daughter populations along different ecological paths results in increased diversity - difference - between them over time. That is how the small amount of difference we seen below can become the amount of difference we see between other bird species.
Again, overrated influence from the environment but this is really a side issue, but anyway, the increased diversity is completely the result of the change in gene frequencies brought about by the population split. If the environment contributes an influence that further impacts the population numbers or reproductive isolation and therefore the gene frequencies, then it will contribute to the trait differences between the populations as well, but again, there is no need for this to happen in order for even great differences to come about as the change in gene frequencies alone will do it.
Continued evolution causes more change - in each population, from generation to generation to generation
Along with change in gene frequencies which can rapidly reduce and even eliminate some alleles as the changes continue, to the point that you run out of alleles for enough traits that further change is impossible, probably a very interesting new population with new traits but no more genetic variability.
That should be enough for starters. There is more to discuss about where change occurs, but this is long enough for now. This thread is about evolution after speciation.
A total pipe dream I'm afraid, as speciation is most likely to occur at the very outer edges of the genetic variability of the species, thus preventing further evolution.

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