I've had an obsession growing about phase shifts. The model is astoundingly general; I wish I knew enough to challenge or to accept the math and computer models.
Homeobox (nonsequitur)first struck me as a wonderful lead on evolutionary changes however, the information has been available since '85 or before. Plenty of time for the Leadership to announce Final Solutions.
The core problem is still that of producing sufficient males and females of a new species to allow generations to occur without the crippling effects from recessives. We are almost boxed (sic!)(a term for bad puns, I think) into believing that all species are derivatives of very very early forms, created when the primal broth was still hot. Or, intense environmental changes elicit shifts on chromosomal sites that are critical to fertile intercourse. (No mules allowed!). I can understand a solitary mutation but it's not a species unless it breeds with other critters with the same mutation but cannot do so with critters missing the mutation.
I strongly believe that most of what we currently term "species" are likely capable of interbreeding but changes in secondary sexual traits linked to shifts in sensory receptivity means that mating does not occur, even if biochemically possible. "I don't want her, you can have her, she's not right for me." Buss commented that similarity is still the largest factor in mate selection. Sure feeds linkage, SNS, and secondary trait evolution. But, doesn't account for species as often as we find them. I heard a recent clip (can't find the source darn it, need to ask Applied Ethol)about a camel and llama mix although no contact has occurred between them for 30 mya. Oh gosh, legions of graduate students moving gametes between birds that can't stand each other!