Thanks for the summary.
That's one claim. It's certainly not his primary claim. He first claims that no common ancestor that reproduced and evolved as we see organisms do today could evolve all three.
Isn't that what I said?
quote:
Q writes:
Woese claimed that there was no way that one or more of the urkingdoms could have evolved from any of the others (the prokaryote to eukaryote idea, for instance).
That's his point. I think before deciding if his point has been superceded or is relevant, you ought to at least recognize what the point is.
I did recognize what Woese's point was. I was trying (and still am) to figure out what
yours is.
WK has done a great job pointing out some key points in the paper. I agree that the progenote hypothesis provides an "elegant" solution to the question of precursers. On the other hand, I don't necessarily agree with Woese that there's something - a progenote - that necessarily has to be the ancestor of all three domains. More likely WK's precursor "community", where a single lineage is either indetectable or non-existent. On the other (other) hand, it is obvious that there was
something that preceeded the rise of the three domains. However, the Rivera paper I cited clearly indicates that at least the earliest eukaryotes may have been chimerae. A hypothesis, btw, which supports Woese's idea that none of the three domains evolved into any of the others, but concurrently refutes his hypothesis about an identifiable "progenote", at least as far as eukaryotes go.
When we get down to the faint, fine line between the RNA world and the cellular world, there's very little hard evidence available, and speculation/data interpretation is relatively open. Given lateral gene transfer, genomic fusion, etc, at that level, and a much larger database today on genome sequences than Woese had available, we can even trace some specific inter-domain transfers. At the level Woese is talking about, these transfers relate to swapping operons and functional protein sequences among a group of non-genetic (as we understand the term) "organisms". These critters may not even be "life-as-we-know-it".
Be that as it may, the primary mechanisms of evolution - random changes and natural selection (especially purifying or stabilizing selection on functionality - see the Omlechenko paper I cited previously) would of necessity be operant. Thus you're going to have to be patient and explain why you think Woese's paper provides some kind of refutation or challenge to evolution. The ToE appears to be operating even at that pre-genetic level. Just not lineal descent, although even there we aren't sure what was going on down in the mud.
I still don't see what the fuss is about.
Edited by Quetzal, : eliminating "actually"s - three in a row was too much