Chapter 10: Biodiversity Section 10.1: Biodiversity at Risk

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

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.

Hawksbill Sea Turtle

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.

WHIPSNAKE

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. 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

Illegal hunting called

poaching, threatens

developing countries’ organisms.

An exotic species is a species that is not native

to a particular region.

Exotic species can threaten native species, which have no

defenses against them.

European

Eel

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the U.S. were originally made from living things.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