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Author Topic:   Where do Creationists think the Theory of Evolution comes from?
U can call me Cookie
Member (Idle past 4984 days)
Posts: 228
From: jo'burg, RSA
Joined: 11-15-2005


Message 71 of 109 (262812)
11-24-2005 5:27 AM
Reply to: Message 40 by Faith
11-21-2005 3:40 PM


Ok, sorry for this being off-topic but I kinda can’t let this go.
It seems, faith, that you do have a bit of background knowledge when it comes to genetics, but there are a few things that you seem to have misunderstood (which you’ve admitted, granted). Your argument for the impossibility of evolution falls apart when you take the following points into consideration:
If you’re gonna talk about natural selection reducing variation, know that natural selection will affect an advantageous (or disadvantageous) allele - positive or negative selection - decreasing diversity at that allele, and maybe those alleles of neighboring genes (hitchhiking). The rest of the genome is still free to be as variable “as it likes”.
Genetic Drift in the form of bottlenecks and founder-effects, on the other hand, will decrease variation globally, across the genome, but I digress.
What one should realize is that genetic diversity i.e. variation has little to do with speciation! A homogeneous species can evolve just as much as a heterogeneous species, barring the fact that you are more likely to find an advantageous allele in a heterogeneous species, due to sheer numbers of alleles.
It is Genetic Differentiation that results in speciation, i.e. is one population genetically different enough from another population, to constitute a new species? Remember, not many species exist in a single population.
It is not natural selection per se that results in speciation. It is natural selection in a population of an initial species, without gene flow to/from another population of the same species, that results in increased population differentiation, to the point of speciation. The new species is thus an “off-shoot” of the initial species, and the initial species does not necessarily cease to exist.
Hope this helps you understand the flaws in your argument, allowing you to “adapt”
As an aside, there is, in fact, a form of natural selection that promotes increased variation! viz. Balancing Selection; an example of which being the sickle-cell trait. While homozygotes for this develop sickle cell anaemia, heterozygotes are quite healthy and at the same time, are more resistant to malaria than homozygous wild types.

So intimate that your hand upon my chest is my hand,
so intimate that when I fall asleep it is your eyes that close.
- Pablo Neruda

This message is a reply to:
 Message 40 by Faith, posted 11-21-2005 3:40 PM Faith has not replied

  
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