Foundational Falsehoods of Creationism - Pt11  By: Aron Ra
All these reveal that life is a fluid dynamic producing new and
subtle variation with every descendant. But evolution only
occurs when new alleles are spread throughout a given community.
This is where selection comes into play, because the parent gene
pool actually does more to inhibit new aberrations than to
promote them. A smaller gene pool is much easier to influence.
So what you usually get are more significant changes emerging in
smaller colonies that have been genetically isolated from the
main population. Eventually, they may get to the point where the
two groups are distinct, where a trait now held in common by
every member of one group is not shared by any member of the
other group. This is known as a subspecies, or “breed”. If the
two groups resume interbreeding, then all that may meld together
again as if it had never been. But if they’re isolated long
enough, they will continue to drift further apart both
physically and genetically unt