Kotatsu
Phthirapterist
Ah, so you took his question to mean "Is there another mechanism we can use to infer common descent?" I'm not sure if that's what he meant or not (figuring out his word salad is almost impossible sometimes,) but you gave a very interesting response.
We found a genome wide duplication event in the poplar genome project, which was probably caused by a paleopolyploid event sometime over the course of its divergence from its common ancestor with A. thaliana. Apparently these events happen very often in plants. There has been some speculation that they are a major cause of speciation in plants.
Well, as Kleinman apparently lack the mental skills to understand anything of what I said in my last two posts (as evidenced by his almost complete lack of response to them), I may as well ignore him, and continue talking to you.
I took his question to mean both any process which would give common descent and any process from which we may infer common descent, as the latter, it seems to me, is a subset of the former. Of course, just sexual reproduction, regardless of if mutations happen or not, will "give" common descent of the progeny of any given stage. Even asexual reproduction will do so, provided each individual gives rise to more than one progeny. That's how I see it, at least. In a sense, at least, common descent does not require evolution. Me and my sister would be of common descent even if our respective genomes were 100% identical, so his question is what we could expect of a man who has no idea what he is talking about.
However, if he means some mechanism or process or evidence we can use in present day organisms to infer common descent of at least some organisms (1), and we cannot use (random point) mutation and selection, then polyploidisation immediately springs to mind. Of course polyploidisation is often coupled to mutation and selection (2) (and to a change to an asexual lifestyle, at least in animals), but even without it, common descent could still be inferred.
I think it is telling that Kleinman choose not to comment on that post at all. My guess is that, again, he has no idea what is being talked about in his presence, and thus he runs below deck and closes the hatches behind him.
As for the last part of your post, I have seen that as well --- 80% of all flowers have polyploid forms or some such number (I think this number was from Otto and Whitton, 2000). The numbers in animals are less, which I have seen explained as a result of animals being less inclined to self-fertilize, but this is doubtlessly only part of the explanation. However, Okano (I think) found evidence that polyploidisation had occurred at least twice basally in the vertebrate phylum, but I don't know the details of it. I've also come to understand that it's more common in colder climates (Little et al., 1997 springs to mind, and also some papers the now infamous Paul Hebert were involved in, but I can't remember who were the first authors of those papers).
In all, I find polyploidisation extremely interesting, and sort of miss working with it. Do you work with it at present?
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(1) Interesting side question: if we could show beyond any doubt that a certain group of organisms had evolved in a way that even someone as dense as Kleinman would accept it, would that be perceived as a localized evolution event or evidence that all organisms have evolved?
(2) Again, Song et al., 1999 is an excellent example of this. However, it is a study of allopolyploidisation, not autopolyploidisation.