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Well, no. I’m talking about the whole here, not the constituent genes. What I mean to say is that no matter how much shuffling of the genes is done, at the end you still have exactly the same number of them, if there are no mutations. The result can only code for a human; this is never going to change
I can’t see how. There’s still going to be the same number of chromosomes and all the cellular machinery is going to remain the same. What mechanism do you propose which would cause reproductive incompatibility?
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It seems to me that speciation without mutation is at least mathematically possible, though I wouldn’t know how to work out the odds.
I imagine a scenario like this: A population contains some gene X and some other genes Y[sub]1[/sub], Y[sub]2[/sub], . . ., Y[sub]n[/sub], but it is extremely unlikely for any single individual to possess all the genes in {Y[sub]1[/sub], Y[sub]2[/sub], . . ., Y[sub]n[/sub]}. Indeed, it is so unlikely that it has never happened. However, if such an individual arose, it would have dramatically improved reproductive fitness. In addition, it would not be able to reproduce with individuals carrying X.
Now suppose that the population is divided into two separated populations P[sub]1[/sub] and P[sub]2[/sub]. In P[sub]1[/sub], through a variety of historical accidents, gene X spreads until all members carry it. In P[sub]2[/sub], by chance, an individual with all the genes in {Y[sub]1[/sub], Y[sub]2[/sub], . . ., Y[sub]n[/sub]} is born. Because this gene combination is so advantageous, the entire population eventually consists of this individual’s offspring, who also have all these genes.
Given these assumptions, you would now have two populations that could no longer interbreed, so speciation would have occurred.
On preview, I see that Blake gave a more biologically informed account of how speciation could occur without mutation. But as far as I can tell, the scenario I described is another way it could happen.