Amborellaceae or Nymphaeaceae first??

STEPHEN MANNING SDMANNING at ASUB.EDU
Tue Jan 13 12:02:58 CST 2004


Without any specialized knowledge of Amborellaceae, my comment is that it
does not seem at all unlikely that the eight-nucleate type evolved more
than once, especially in light of the general diversity of female
gametophytes and their development in Angiosperms.  Maybe some careful
ontogenetic studies of the series of cell divisions in Amborellaceae and
various eight--nucleate gametophytes could elucidate some informative
detail differences, or the lack thereof? Or might the four-nucleate type in
Amborellaceae be derived by subtracting a division from an eight-nucleate
condition??

Just thoughts since you asked for comments!

Steve Manning

At 06:39 PM 1/12/04 -0800, Ken Kinman wrote:
>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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Stephen D. Manning, Ph.D.
Professor of Biology
Mathematics and Science Division
Arkansas State University - Beebe
P. O. Box 1000
Beebe, Arkansas 72012-1000
USA
Tel: 501-882-7162




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