No, I know better than that. I was just looking for a discrete, measurable event that I could hold for discussion.
I hope you don't take this the wrong way...but I would find myself responding to you more favorably if you would stop disparaging my intelligence. You seem to take me for a creationist, which is no doubt the source of your disdain; what I am, however, is a layman with no vested interest in either direction.
Sorry, I won't be so contemptuous then. It is just that scientists who debate creationists keep hearing the same old debunked arguments over and over. It gets frustrating.
Actually, a chromosome number change would probably indicate a wider divergence than species. For instance, a piece could break off, but not change the genetics and still be the same species or a chromosome pair could duplicate and not change anything, but be there to mutate and eventually become active.
Or the whole chromosome set could duplicate without causing any infertility. Also remember that chromosome number changes in asexually reproducing organisms would immediately result in a new species.
I've tried to explain myself in these terms in the past to no avail. To the zealots on Darwin's ping list, if you are not fully persuaded that mollusks are in your family tree, you are initially branded as ignorant.
For the ignorant, they recommend reading basic bio books and talk origins articles. If you have a specific question and the article they reference does not actually address the specific question or is otherwise unpersuasive to you then you move into bucket #2, you are duped.
For the duped, the good ping-doctors of Darwinian zealotry assume you are under the sway of evil creationist liars. The prescription for such is to insist that your question is nothing but the rehashed tripe of creationist liars dating all the back to the 19th century (nothing new here). They loudly pronounce the proven idiocy of known creationists and try to get you to denounce them as well. If you fail to repent and recant then you are then proven to be evil because you are siding with the lie.
Once branded as evil, they know you lie, so they tell you what you really believe and scourge and mock you and spit upon you for the sins they know you commit even though you haven't done so on a particular thread.
Their closed system requires that there is no such thing as honest intelligent scientific debate about the adequacy of mainstream evolutionary theory. If there were such thing as an honest scientific debate about whether the Modern Evolutionary Synthesis is true, it would belong in schools as science. This they cannot abide.
Of course not all are zealots but there is a substantial population of this particular species.