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Re: Of Tarbosaurs and tabbies

On Thursday, March 18, 2004, at 12:35 AM, Thomas R. Holtz, Jr. wrote:

From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of

I should know this already, but when did the lion and tiger diverge?
Would it be accurate to say they are each branches of the same species
on the path to distinct speciation? If so, do they therefore represent
transitional forms, of the type so coveted in the fossil record?

No, lions and tigers are about as secure as species as any two taxa are. It
is fairer to say that these are two distinct species in which genetic or
morphological features to prevent interbreeding have not evolved.

OK, but doesn't that really amount to them being in the incomplete process of diverging from each other? Shouldn't they only become distinct species when they can no longer interbreed at all? Currently they can still do so, but the results are inconsistent, and will presumably eventually amount to nothing when they've evolved away from one another sufficiently.

As Darwin
showed, regional varieties grade into subspecies which grade into species:
there aren't distinct breaks between these "ranks".

I suppose really every critter is a transition from one thing to another. I do think "species" has been assigned all too readily, but it seems we're moving away from that - good to see.

Peter Markmann