So, when we lose biodiversity, we lose access to many different plants and animals that we might need. Many of our prescription drugs were first made from plants and animals. If we continue to lose species, especially those not well researched such as those in tropical forests, will lose out on potentially valuable medicinal cures. Ecosystems also help clean the air we breathe and the water we drink. Without wetlands to purify water and forests to screen out pollutants from the air, we would need machines to provide this service.
Biodiversity stabilizes the ecosystem.
It keeps our options open for the future. There may be resources out there that we don't yet understand their potentials, and we don't want to destroy them before we even know about them. Biodiversity also increases the beauty of the planet. Trying to preserve either a single animal or even the ecosystem are both good ideas if in the long run they work to save the area. When you try to save an individual animal, especially a keystone species , you must provide it with a place to live and food to eat.