"Species" is, in and of itself, a man made construct. To define your own morals by an arbitrary distinction isn't just simplistic, it's downright dangerous.

It wasn't long ago that certain people were considered "subhuman", and therefore open to all kinds of abuse. Did you learn nothing from that?

And of course, the same is true for your ridiculous "might makes right" argument. Have you considered making other horribly uneducated arguments, like "it's natural"? Maybe add some "we've always done it that way".