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Is Carl Woese losing a Kingdom?

James O. McInerney PhD j.mcinerney at nhm.ac.uk
Tue Sep 24 10:21:36 EST 1996


Jonathan Badger wrote:

> So you are saying that protists with a non-mitochondrial plastid, had
> mitochondria, lost them, did perfectly fine without any plastids for
> a while, and *then* picked up non-mitochondrial plastids at a later
> point?

Nothing so elaborate.  Simply, some protists such as Trichomonas
vaginalis do not have mitochondria at the moment.  Their ancestors
clearly HAD mitochondria (Horner et al., Proc. Roy. Soc. Lond. B series.
1996) but the extant species does not have one.  This is not the only
example, but to split protists up on the basis of
mitochondrion-containing and mitochondrion-lacking is not a proper
phylogenetic division either.

I'm sure there was a single mitochondrion-forming endosymbiont, but its
descendents are not present in all the hosts descendents today.

Don't think that I disagree with you on the question of the monophyly of
protists.  I don't think that anyone will argue that all non-plant,
non-fungi, non-animal eukaryotes are a monophyletic group called
protists (or even protoctista).  Its just that their primary split is
not on the basis of possesion of a mitochondrion.

james

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Dr. James O. McInerney Ph.D.        Phone/Voicemail: +44 171 938 9247
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The Natural History Museum,         
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