Natural Pressure

[alextemplet]

I think introduction of species can be caused by other animals also what do you say?

Yes, it can.

[AstusAleator]

Well, we might be getting back into the nature vs humans debate again, or maybe it's just semantics, but I generally think of "introduced" species as species that wouldn't have "naturally" found their way to a particular area.
For example, I think it's natural when an eagle catches a female bass full of fertilized eggs, and then accidentally drops her corpse into a pond somewhere remote where bass could never have been through the process of biogeography. The bass are being introduced, but by natural means.
So yes, species can be introduced naturally, but I don't see that as anything more than an extension of genetic drift. The theory of island biogeography includes in it the possibilities of this sort of genetic drift.
I think that natural species introduction is fairly well integrated into the theory of evolution. However, unnatural "human" introduction is not accounted for very well by the TOE.

[Khaiy]

I think that the current TOE does cover that, since the species that are introduced/were already there would feel selection pressures presented by the other organisms. It doesn't cover what would naturally happen without any human intervention, but the TOE really just describes pressures and responses to them. Am I forgetting something from the theory?