Biodiversity:

What are ways in which preserving biodiversity locally might have a global effect?
Drugs(medicine) that have not yet been found might be in a plant or an animal native to an area but if something were to happen to that area than that drug/ cure might be gone for good. When we hurt our world we hurt ourselves.

How do habitat destruction and loss of species effect more than just one area?
If you harm a species or multiple species in one area than the species predator may have to go looking other places and venture from theirs. This creates a smaller food supply and could cause that species to go extinct.

How does preserving biodiversity enhance the life of people?
Better air because more is being produced by plants. Animals will not wander into homes if their's are not destroyed first.