From: Neil Carroll zzamia at hargray.com> on 2002.02.02 at 04:48:29(8129)
>
>I think it is highly unlikely that ANY permutation of an Amorphophallus
>(for example) is going to head in the direction of looking like the fly
>that pollinates it, regardless of how many million years you leave it.
No, but it certainly has developed a smell which the fly that pollinates is
highly attracted to. Pollination is not the only character that would be
subject to natural selection. Large leaves are selected for plants which are
perpetually in low light to gather more light. Those with small leaves were
left behind.
So
>why does a particular orchid look so much like it's pollinator to the point
>that you can mistakenly at a first glance think that it is a wasp sitting
>on the flower, rather than it being the flower itself? What made the
>orchid head in that direction in the first place?
They did not chose what direction to go in, they only develop and change in
the direction that their environments choose. Sometimes mutations and/or
hybrid swarms may develop and stabilize into a new spieces, thus skipping
several tens of thousands of years of natural selection. Orchids that are
pollinated by 'pseudocopulation' (bug mimics) are at the cutting edge of
millions of years of evolution. When you think of the sheer legth of time
(millions of years) that these plants had to try out the various
combinations and permutaions...it is not such a stretch.
The point that natural selection can be sped along by chance mutations or
hybridizations also shows that time can be compressed and many combinations
and permutations are skipped over. But the survivors still have to survive.
Sudden geological changes can also promote new "trys" at evolution.
The inundation of the Panamanian Isthmus was not that long ago in
evolutionary time, yet due to the isolation of many mountain tops into
islands, a great deal of endemism occured there in a short (realitivly
speaking) time.
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