According to a biology conference, there are many definitions of keystone species. 1 says that if it goes extinct there will be a drastic change in the rest of the ecosystem. But the other one says that if it goes extinct all other species in the ecosystem will go extinct. I do highly disagree with the second definition because that would put us in the catagory of the top predator but we are not the top predator in any ecosystem because even though we are feared by most species we do not nessesarily feed off of them