At 4:17 PM -0500 10/4/99, Donna I. Ford-Werntz wrote:
>Although I can't comment based on evolution of specific fossil plants, I
>have heard/read (but can't recall from who/where) that dominance of the
>diploid, rather than haploid, may offer more evolutionary flexibility
>(therefore greater success) from the standpoint of mutational variation and
>natural selection.
>>Donna I. Ford-Werntz West Virginia Univ.
>>Herbarium Curator (WVA) Box 6057
>>Asst. Prof. Biol. Morgantown, WV 26506
>>425 Brooks Hall (304)293-5201 X2549
>>email: diford at wvu.edu fax: (304)293-6363
>>Web site at http://www.as.wvu.edu/biology/>
To me, the "beauty" of the diplophase is that
it shelters recessives and keeps this pool of
alternate alleles against a changing environment
in the evolutionary future of a species.
This idea is consistent with the extreme reduction
in the haplophase to one or a few very specialized
cells with only a few genes operating. The two/three
celled microgametophyte and the "around-seven" celled
megagametophyte are strong supporting evidence in
flowering plants. Most animals have reduced the
haplophase to single cells.
ross
________________________________________________________________
Ross Koning | koning at ecsu.ctstateu.edu
Biology Department | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA | fax: 860-465-4479
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