Gender Separation in Nature

[Archangel]

Very recently, I begun pondering on something that might be a little much for me alone to grasp...

What is it that caused multi-cell organisms to split into genders?

Or even - why they became hermaphroditic in the first place?

Reasonably speaking, to put the survival of the species, or even the continuation of one's own genes into the hands of another doesn't seem very wise or "fit". We could say that it increased the chances for mutation and accelerated evolution, but on the other hand, it means very little compared to the most resilient organisms on the planet - I'm talking about various single-cell organisms, who reproduce by mitosis and seem to be able to adapt to just about anything one can throw at them. They can even withstand severe conditions like the ones on the Moon surface, probably on Mars also, extreme temperature and pressure variations etc.

So, what is the upside to "genderization"? How does becoming dependent on another for reproduction make a species more fit than the alternative? What mechanism fathered it?

[Calrid]

I think the answer is complexity.

"It is not the fittest of the species that survive but those most able to adapt."

The Darwinator.

Single cells can adapt rapidly through cloning themselves because they don't need to invest a large amount of time in the process so mutation occurs regularly. Complex organisms cannot produce offspring quickly so adaptation would be limited. Hence more rapid adaptation of complex life fathered it, with the complex organisms who cloned themselves being more likely to fall to disease, predation etc. I think it was a continuum though, as you say hermaphroditism may well of come first, followed by discrete sexes. I suppose it's complex though as some organisms can actually change sex.

[Archangel]

I see..

But, if complex organisms cannot adapt quickly enough, why didn't they simply disappear? Revert to being just single-cell? Instead, they maintained complexity and continued further from there...?

[Calrid]

I see..

But, if complex organisms cannot adapt quickly enough, why didn't they simply disappear? Revert to being just single-cell? Instead, they maintained complexity and continued further from there...?

They could not adapt quickly enough through cloning.

They found a way through sexual selection to adapt quickly enough, probably took millions of years for something like sexual selection to appear and millions more for it actually to appear.

I'm no expert so:

http://en.wikipedia.org/wiki/Evolution_ ... production

It's all pretty hypothetical stuff but the logic is pretty clear.