Amborellaceae or Nymphaeaceae first??

Ken Kinman kinman2 at YAHOO.COM
Mon Jan 12 18:39:35 CST 2004


Dear All,
      The general consensus presently has
Amborellaceae as the most primitive clade of extant
flowering plants, and then Nymphaeaceae as the next
clade to split off (and that's how I coded it in my
angiosperm classification presented here, May 2003).
However, Amborellaceae's claim to being the first is
apparently being disputed in at least two recent
papers:

     (1) Goremykin VV, Hirsch-Ernst KI, Wolfl S, and
Hellwig FH.  2003.  Analysis of the Amborella
trichopoda chloroplast genome sequence suggests that
Amborella is not a basal angiosperm.  Mol. Biol.
Evol., 20(9):1499-505.

     (2) Friedman WE, and Williams JH. 2003.
Modularity of the angiosperm female gametophyte and
its bearing on the early evolution of endosperm in
flowering plants.  Evolution Int J Org Evolution,
57(2):216-30.

     The first paper listed above would not concern me
too much in isolation, but the paper by Friedman and
Williams also seems to dispute the present consensus
phylogeny since Amborella apparently has female
gametophytes of the more derived eight-nucleate
(double module) type.  Of course, I guess it's
possible the eight-nucleate type evolved more than
once.  Anyway, Nymphaeaceae is one of the few
angiosperm families with the four-nucleate (single
module) type.  Any comments?
         ------- Cheers,
                    Ken Kinman


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