andrel <byt### [at] gmailcom> wrote:
> On 21-5-2012 12:51, Invisible wrote:

> > In particular, the purpose of leaves is to absorb as much sunlight as
> > possible. Given that task, you would /expect/ leaves to evolve to be
> > huge flat sheets.

> Huge flat sheets would mean that only the outher layers get sunlight. 
> Inner branches might just as well commit suicide immediately.

  From an evolutionary point of view, trees are the result of an
evolutionary arms race.

  Tree trunks are basically a huge waste or resources. A tree doesn't
benefit much from an enormous trunk of wood; it doesn't serve much
biological purpose. The only reason why trees have such enormous wastes
of resources is to simply get its leaves higher than the competition.

  If all the trees in a forest were like 1 meter high, that would be
enough. However, immediately when one of the trees gets a slight mutation
that makes it grow a bit taller than the rest, it gets a survival advantage
while at the same time lessening the survival chances of the other trees
around it (because now the taller tree is blocking the sun for them for
a period of time). One such tree might not do much damage to others, but
when it reproduces and its offspring start shadowing other trees en masse,
those other trees are going to have a hard time getting any sunlight at all.
Thus the tallest of those other tree species are going to get naturally
selected from among their shorter brethren, and so on. Thus we end up with
gigantic trees which may reach even 100 meters.

  Dense forests with tall trees tend to be relatively barren of other
plant life, save for plants that survive on low light conditions. Something
like this: http://i304.photobucket.com/albums/nn198/toshi0723/CIMG1966.jpg
(Compare to something like
http://en.wikipedia.org/wiki/File:Hokkaido,_Sarobetsu_Plain.jpg )

-- 
                                                          - Warp

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