Chapter 5 Summary

  Global climate change, including warmer temperatures and changing precipitation patterns, is already occurring because of the large amounts of carbon dioxide and other greenhouse gases produced by the burning of fossil fuels and deforestation. Predicted temperature increases may be so rapid in coming decades that many species will be unable to adjust their ranges and will become extinct.

  Overexploitation is driving many species to extinction and can consequently undermine entire ecosystems. Overexploitation is the result of increasingly efficient methods of harvesting and marketing, increasing demand for products, and increased access to remote areas.

  Humans have deliberately and accidentally moved thousands of species to new regions of the world. Some of these nonnative species have become invasive, greatly increasing their numbers at the expense of native species.

  Levels of disease often increase when animals are confined to nature reserves, zoos, or habitat fragments and cannot disperse over wide areas. In zoos and botanical gardens, diseases sometimes spread between related species of animals and plants. Diseases may also spread between domesticated species and wild species, and even between humans and both wild and domesticated animals.

  Species may be threatened by a combination of factors, all of which must be addressed in a comprehensive conservation plan.