How might an introduced plant species kill native plant species?

Is anyone else getting discouraged by all the questions advocating the eradication of one species or another?

• What I mean is questions like "Why don't we kill all the flies?" or "why dont we kill all sharks and alligators, what purpose do they serve anyway?" Seriously it makes me very sad to think that people can so casually suggest and accept genocide of an entire species, I mean who are we to play God or Mother nature? We haven't even begun to understand the complexity of interspecies relationships and the impact extinction can have on an ecosystem. What little we know shows how devastating the loss of any species can be, just look at what happened in Yellowstone when they killed all of the wolves the impact was tremendous and affected every other species of animal and plant in the park. I mean how can someone actually want to kill every single member of an entire species and not feel bad about it? What do you think, and why? and Do you compare it to the mentality that caused the holocaust? I know I do and it scares me that people even think of killing an entire group of living creatures.

• Answer:

  What I don't understand is the need for the rationalization for the supposed "purpose" of a certain animal. People tend to be very ego-centric in terms of our world, as if God made it man's personal playground to do with as we will. So if an animal annoys us, or serves no obvious purpose, then we should eradicate it? Doesn't any living organism deserve to exist simply for the sake of existence? And if we are going by terms of "usefullness" then why not eradicate the whole human species. We are responsible for the most destruction to natural habitats on a global scale, and there is nothing in existence to balance out our overpopulation problem. So in effect we are the most detrimental to the health of our planet. See the logic in that?