i'm sorry i know we're not supposed to turn this into a back-and-forth, but this comment is just so incredibly misrepresentative that i just
have to correct the misinformation.
Best way I know to explain and illustrate this is with dog breeding. All canines (all canine species) can actually successfully interbreed, and you can take a group of canines or dogs and create specific forms. Pure-bred dogs are a good example of that.
But what happens when you do that?
The genetic range within the breed is diminished. That's one reason so many pure-bred dogs have so many problems.
the diminished genetic range in purebred dogs (and their genetic problems) are caused by
inbreeding. pure breeds are often created by mating dogs that are
very closely related. this does not happen (to this extent) in the wild, where genes are distrubuted normally in more random distributions. the difference here is breeding population size -- human meddling with artificial selection.
problems are also caused because that artificial selection is for traits that would not normally be selected for in the wild, produce dogs that are less fit for survival independent of humans.
artificial selection is not a good model for natural selection, because we humans select for different criteria than nature. "survival" may not even be one of them. i mean, look at ray comfort's banana -- it can't even breed on its own without humans. if such a mutation happened in nature, it'd be dead in the first generation.
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