Paper: Embryological evidence for developmental lability during early angiosperm evolution

Accepted 1 March 2006
Embryological evidence for developmental lability during early angiosperm
evolution
William E. Friedman

Abstract:
Recent advances in angiosperm phylogeny reconstruction, palaeobotany and
comparative organismic biology have provided the impetus for a major
re-evaluation of the earliest phases of the diversification of flowering
plants. We now know that within the first fifteen million years of
angiosperm history, three major lineages of flowering plants-monocotyledons,
eumagnoliids and eudicotyledons-were established, and that within this
window of time, tremendous variation in vegetative and floral
characteristics evolved. Here I report on a novel type of embryo sac
(angiosperm female gametophyte or haploid egg-producing structure) in
Amborella trichopoda, the sole member of the most ancient extant angiosperm
lineage. This is the first new pattern of embryo sac structure to be
discovered among angiosperms in well over half a century. This discovery
also supports the emerging view that the earliest phases of angiosperm
evolution were characterized by an extensive degree of developmental
experimentation and structural lability, and may provide evidence of a
critical link to the gymnospermous ancestors of flowering plants.

Abstract and Full Text links at Nature
http://www.nature.com/nature/journal/v441/n7091/abs/nature04690.html

Posted by
Robert Karl Stonjek


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