Chapter Summary

In this chapter, we have briefly surveyed world biodiversity and the ways humans both benefit from and threaten it. Natural causes of wildlife destruction include evolutionary replacement and mass extinction. Among the threats from humans are overharvesting of animals and plants for food and commercial products. Millions of live wild plants and animals are collected for pets, houseplants, and medical research. Among the greatest damage we do to biodiversity are habitat destruction, the introduction of exotic species and diseases, pollution of the environment, and genetic assimilation.

The potential value of the species that may be lost if environmental destruction continues could be enormous. It is also possible that the changes we are causing could disrupt vital ecological services on which we all depend for life.

The first hunting and fishing laws in the United States were introduced more than a century ago to restrict overexploitation and to preserve species for future uses. The Endangered Species Act and CITES represent a new attitude toward wildlife in which we protect organisms just because they are rare and endangered. Now we are expanding our concern from individual species to protecting habitat, threatened landscapes, and entire biogeographical regions. Social, cultural, and economic factors must also be considered if we want to protect biological resources on a long-term, sustainable basis.

Zoos can be educational and entertaining while still serving important wildlife conservation and scientific functions. Modern zoos have greatly improved the living conditions for captive animals, resulting in improved breeding success; still, there are limits to the number and types of species that we could maintain under captive conditions. Zoos need to get out of their own walls and help save animals and plants in the wild.