Transcript Biodiversity - Cloudfront.net

Biodiversity
•Biodiversity refers to the number and variety
of species on Earth.
•The number of known species on Earth is
about 1.6 million, most of which are insects.
•This is different from the actual number of
species on Earth, which may be closer to 100
million.
Importance of Biodiversity
•Biodiversity provides:
 a variety of products and resources
 a livable planet for us and for all other species.
•Biodiversity helps:
maintain the atmosphere
keep the soil fertile
purify water
Loss of Biodiversity
1. We share the environment with other organisms
in a complex network.
2. Each species has a role or niche to play in its
ecosystem.
3. If one species disappears from an ecosystem,
the ecosystem changes.
Keystone species are species that are so
important to the functioning of an ecosystem
that if they disappear, the ecosystem falls
apart.
An Example in Texas:
Black-tailed Prairie
Dogs
• Black-tailed prairie dogs once
roamed the western mid-west.
Now cover less than 1% of their
original territory.
Digging aerates and promotes soil
formation.
Clip back brush maintaining the
short grass prairie.
Provide food and shelter for as
many as 170 different animals.
Main Threats to
Biodiversity
• Habitat loss
• Introduced species
• Population growth
• Pollution
Habitat Loss
• the destruction of habitats is the number
one cause of species extinction.
Turn and Talk
•How does habitat loss affect biodiversity in an
ecosystem?
Introduced Species
• Nonnative or Exotic species that are not native to a
particular region.
Fire ants from South America entered the U.S. through
Mobile, Alabama, probably in soil used for ships' ballasts.
They were accidentally introduced around the 1930's and
have been spreading ever since.
Turn and Talk
•How do introduced species affect biodiversity
in an ecosystem?
Population Growth
• There are 7 billion humans living on Earth.
• Earth’s population of human beings is increasing at a rate of
about 222,000 people each day.
• Humans take up more space and deplete more resources than
any other species.
Pollution
• Can be an oil spill, acid rain, trash or
insecticides that can cause reproductive
failure in fish, birds, and mammals (like
DDT).
Turn and Talk
•How does pollution affect biodiversity in an
ecosystem?
Extinction
Extinction occurs when the last individual of a species dies.
San Marcos Gambusia, Texas, 1983
Texas red wolf, Oklahoma, Texas, 1970
Texas gray wolf, New Mexico, Texas, 1942
Mass Extinction
•
•
•
The extinction of many species during a
relatively short period of time.
Often caused by a change in climate.
Many scientists believe that we are living
in a mass extinction, and that by the year
2100, 25% or more of all species of
plants and animals that were on Earth in
1900 will have become extinct.
Turn and Talk
•How will this mass extinction affect Earth?