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Re: "reticulation" (in metazoans)




David,
Correct. Metaphytes (bryozoans and other higher plants) inherited chloroplasts directly (vertically) from their chlorophyte (specifically charophyte) ancestors.
The hypothesis I was referring to (early 1990's?) has something to do with a major horizontal infusion of genes that may have triggered the evolution of the metaphyte rooting system. Could explain why so many metaphytes still have symbiotic relationships with eumycotans (higher fungi) around their roots. Not sure how well this hypothesis has been received.
------------Ken
******************************************************
From: "David Marjanovic" <david.marjanovic@gmx.at>
Reply-To: david.marjanovic@gmx.at
To: "The Dinosaur Mailing List" <dinosaur@usc.edu>
Subject: Re: "reticulation" (in metazoans)
Date: Tue, 5 Jun 2001 13:05:07 +0200

> > If I recall correctly, someone has
> > proposed that Kingdom Metaphyta may have arisen as the result of a major
> > symbiogenetic (horizontal) transfer event, but haven't read anything
about
> > that recently (I'm not much of a botanist). >
>
> Right: the chloroplasts of all green plants. And chloroplasts contain some
> ADN [French for DNA].


Assuming Metaphyta are the multicellular plants (are they?), chloroplasts
have transferred themselves much earlier, into a common ancestor of green
algae (including plants), red algae and glaucophytes (a few odd unicellular
species whose chloroplasts retain the bacterial cell wall). And then
unicellular green algae got into euglenids and unicellular red algae into e.
g. the common ancestor of yellow, brown, and golden algae and diatoms --
secondary endosymbiosis. Tertiary endosymbiosis is also known, and I have
even heard rumors of eightfold endosymbiosis!!!


However, even this doesn't make cladistic analysis impossible or even
useless in finding out the origin of such groups. One just needs to keep the
parts separate -- to identify horizontally transferred genes and
endosymbionts so that they don't make "noise" in the data matrix.


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