How would the native island species be affected when an invasive species is introduced? # How is pl?

That would depend entirely on the relationship of the two species. Are the introduced invasive prey? predators? competitors? commensals? mutuals? ??????

Let me state this first: I'm an animal lover, trying to be a vegetarian, and convinced that animals should be treated humanely. At first sight, humans are obviously not the centre of the universe, something so special that only they can have rights. If both smart and stupid people have rights, why not "stupid" animals? I admit that people can harm animals and I do not want to minimize these problems. I believe that the solution of the very real problems of animals do not require the invention of new rights. There are other ways to solve these problems. One can make the case that we simply have a moral duty to respect animals. However, duties are less popular than rights and hence the temptation to use the language of rights. But once you extend rights to animals you get on a slippery slope. Why not bacteria? Stones? Sand? ...