To speak about the problems of rare species, you need the appropriate vocabulary.
Inflict on - to make someone suffer by doing something unpleasant to them;
Wipe out - to destroy something completely;
Evolution - the way in which living things gradually change and develop over millions of years;
Survive -  to continue to live after almost dying because of an accident, illness, etc;
Endangered - animals or plants which may soon not exist because there are very few now alive;
On the brink of extinction - on the point close to the situation when animals or plants will not exist;
Ivory - a hard, white substance from the tusks (= long teeth) of some animals, such as elephants (= large, grey animals);
Pesticide - a chemical that is used to kill insects which damage plants;
Toxic - poisonous;
Habitat - the natural environment of an animal or plant;
Ecosystem - all the living things in an area and the way they affect each other and the environment;
Reverse - to change a situation or change the order of things so that it becomes the opposite;
Wildlife - animals, birds, and plants living in their natural environment;
Deleterious - harmful.
Tourism is damaging the fragile ecosystem of the reef.
Many species are on the brink of extinction.
Elephants were being hunted for their ivory.