How can a mutualism between two species arise? I have thinking about this for a while and I have come up with the following points 1.If mutualism gives one specie a competitive edge over its competitors then it could arise. Suppose you are being really pounded by your competitors and there is now way you can survive except if you give in to mutualism, even if it means "selling your soul". 2.The benefits received from the partner species outweighs the costs involved in helping it out.
I cannot think of any more examples. Please suggest a few; also point out if there are flaws in my reasoning.