Date: Tue, 18 Jul 2000 07:48:15 -0700 From: Ivan Snyder <bioexp@juno.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2154$foo@default> Subject: re: Dispersion; Nativeness
Hi CPers,
MY PERSPECTIVE
I am seeing alot on the subject of dispersal of plants from one place to
another, and I think this all started with argument over the case of
Aldrovanda. I myself have done much study into this matter. Here are some
facts to help complicate the matter; some points to ponder as a great
abysmal lesson in futility. Enjoy :-)
BIRD DISPERSAL
Commonly, wetland plants are widely spread by water fowl, as Mr. Wu first
stated here. In California we see plants whose habitats range from Alaska
all the way down through South America. The same species are found
throughout this range where ever there are suitable condition for the
species in particular along the migratory routes of water fowl. One
species known to be spread in this manner is Utricularia gibba. Animals
too are so spread. I have encountered all through California a creature
known as the Apple Snail (apple sized). This snail is also found in the
Pantanal in S. America. In another case much studied is Drosera anglica,
which was apparently spread to Hawaii by a bird the Golden Plover.
Considering this dispersal mechanism, it is often puzzling to figure just
where all these different species are truly native to along an extensive
migratory route, unless there is some visibly different adaption to a
specific habitat. Species may appear, disappear, and later reappear again
along a route. The definition of nativeness becomes blurred with these
transient species. Many carnivorous plants are such transients. All this
must be considered in determining a species range. I feel we must think
of ranges as more flexible, especially over such protracted lengths as
geological time. Distance in itself is clearly not a barrier.
SPECIES IDENTITY
By cross breeding, I have proven that Drosera burmanni from Australia and
D. sessilifolia from Brazil, are essentially the same thing. The hybrid
is fertile. Therefore, there must be exchange of plants between even
these ocean separated countries.
ZEBRA ORIGIN
Paleologists have found that the zebra originated in Texas, N. America.
Where is it native today? This is only one of may such examples I know
of.
WEEDS AND SUCCESSION
At the CP World Conference in San Francisco, Barry Meyers-Rice explained
that even native species showing out of control growth can be termed
"weeds". Is this bad? I don't see it that way. This is part of the
natural process of succession of organisms. A plant may be transported to
a new location where it may find a foothold free of competitors/parasites
and become established and grow unhindered until the all the natural
associates too become established, where upon the plants again move-on to
other locations.
SPACE --THE FINAL FRONTIER?
Mycologists have it more easy, no argument over nativeness. Fungal spores
are wind dispersed. Mushroom species are found anywhere and everywhere
around the world having similar conditions. As time goes on, botanist too
will have to adopt this way of thinking. Plants are becoming evermore
easily transported via the agency of man and his machines. I predict that
sometime in the future, a probe will take a sample of surface ice from
ancient frozen upwelling originally from the interior of the moon Europa,
and find lifeforms identical to some also found on Earth. Nativeness will
then be expanded to the boundaries of the solar system. And then...
Ivan Snyder
Hermosa Beach
California
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