IGIT writes:
Isn't isolation neccesary for evolution?
Nope. Others have explained so I'm not going to waste my time.
So if there are no geographical barriers to separate different groups of a species, can mere distance serve to isolate them?
Yes. Others have explained so I'm not going to waste my time.
Hypothetically, I'm thinking of a species of hare that has a range...let's say 300 miles wide. Wouldn't the genes of all the would-be varieties keep criss-crossing across the range, and keep the species pure? Or if the distance is great enough, can varieties form?
I'd like to point out that you're also forgetting about time as a barrier.
Yes, the genes of all the would-be varieties would keep criss-crossing. But that doesn't necessarily mean a species remain "pure", whatever that means. We know that mutation is bound to occur. And every once in a while, a mutation is bound to create a new phenotype, adding variation to the gene pool. The population as a whole just
evolved.
The population of hare at the said location isn't the same population of hare at the same location a million years ago. And it won't be the same population of hare a million years from now. Enough phenotypic changes over long periods of time could act as a barrier and give us a completely new species.
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