A big frakking plant

aspen by dpatricklewis
The Earth’s Elder:
[Via Discover Magazine | RSS]

The largest organism on Earth, and probably the oldest multicellular organism, is named Pando. Kind of a cutesy name for such an impressive specimen, don’t you think?
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Aspens are nice looking trees. And this one is 80,000 years old and weighs six million kilograms. I guess this is a nice case of vegetative reproduction.

It is as if the trees just keep cloning themselves. This works really well if conditions do not change. This is one of the paradoxes of evolution. Natural selection would seem to drive a species to the single best version, to the top of the fitness peak. Animals on lesser hills would lose the battle.

This is fine as long as the peak fits the conditions. But if things change, it is very risky to have all the eggs in one basket. Then another peak may be the best but since no individual occupies it, there is little hope for the species.

Under changing condition, the best strategy is to have as much diversity in the gene pool as possible. The species that dominate here are those with the greatest dissimilarity between the genetic makeup of individuals. This results in the greatest chance that some of the individuals will survive.

So, in times of stasis, similarity would be a good genetic strategy. In times of crisis, diversity is best. What is a good strategy to have both?

There are many strategies but sex works well. Sex allows genetic diversity to remain high by reshuffling genetic combinations every generation. Enough of the offspring will be similar for the static times but enough diversity can remain for the critical times.

Pando grew to its size by not using sex. And while there is some discussion of the conditions required to get aspens to spread by seeds, they can reproduce by sex when the conditions require it. I would imagine that if events warranted it Pando would find some female aspen to mate with and send out lots of seedlings, just like any other metazoan.

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