Chapter 10: Biodiversity Section 10.1: Biodiversity at Risk

The last dinosaurs died about 65 million years ago. The dinosaurs disappearance was part of a mass extinction.

Mass extinctions are the extinctions of many species during a relatively short period of time. Akiapola’au

Biodiversity refers to the number and variety of species on Earth. The number of species known to science is about 1.6 million – most of which are insects. The actual number of species can range to about 13 million. Blunt-Nosed Leopard Lizard

Hawksbill Sea Turtle The human population of the world is increasing at a rate of 220,000 people per day. Because the human population is growing so rapidly and changing the environment so dramatically, we are causing other species to become extinct at an accelerated rate.

WHIPSNAKE Why is the increase in the human population so devastating to other species? As humans take up more and more space and deplete more resources, we destroy the habitats of other species. Unregulated hunting and the introduction of nonnative species also contribute to extinctions.

It is estimated that habitat loss causes almost 75% of the extinctions now occurring. Houston Toad

Two United States species being destroyed by habitat destruction is the Florida panther and the whooping crane.

However, most extinctions are occurring in tropical rainforests when the land is cleared for farming or cattle grazing.

Unregulated hunting in the U. S Unregulated hunting in the U.S. has lead to the decline of many species including the passenger pigeon and the bison.

Legal hunting is no longer a problem in developed countries. BONE CAVE HARVESTMAN Legal hunting is no longer a problem in developed countries.

Illegal hunting called poaching, threatens developing countries’ organisms.

An exotic species is a species that is not native to a particular region. European Eel                                          Exotic species can threaten native species, which have no defenses against them.

The Value of Biodiversity

Saving species preserves ecosystems It is important to maintain healthy ecosystems because they ensure a healthy biosphere by regulating the flow of energy and the cycling of nutrients. Blackburn’s Sphinx Moth

Practical Use of Species The mass extinction of species represents the loss of a potential gold mine of valuable products. Comal Springs Riffle Beetle

About 40% of all prescription drugs used in the U. S About 40% of all prescription drugs used in the U.S. were originally made from living things. Digitoxin – Common Foxglove Cardiac Stimulant Taxol – Pacific Yew Anticancer Agent

Ethical and Aesthetic Reasons Most people agree that we should preserve biodiversity for ethical reasons. People also value biodiversity for aesthetic reasons – time spent with other living things renews our sense of connection with nature. Appalachian Monkeyface