Download Chapter 5 - Holden R

Biology Chapter 5
Biological Diversity & Conservation
5.1 Biological Diversity

Biodiversity- the variety of species in a
specific area



Rainforests have high biodiversity (400+ species)
Corn fields have very low biodiversity (2-3
species)
Biodiversity increases as you get closer to the
equator

Tropical regions contain 2/3 of all land species on
Earth
5.1 Importance of Biodiversity

Decreased biodiversity can impact nature
negatively:

Loss of one species can increase the species that
organism eats and decrease the species that consumes it


Removal of predators can cause the prey population to
reach the carrying capacity faster
Increased biodiversity makes an ecosystem more
stable

There are more alternate food and habitat sources with
more biodiversity, so it is easier to adapt
5.1 Importance of Biodiversity to
Humans

Humans are dependent on other organisms
for food, building materials, oxygen, etc.

Medicines are often made from plants



The more plants, the more possible medicines
Undiscovered medicines may never be discovered
if the plants are destroyed
Pest resistant or drought tolerant crops can be
created by crossbreeding wild plants & food
crops
5.1 Loss of Biodiversity

Extinction- when all of a species dies




Scientists estimate 1-10 species goes extinct each year
naturally
Humans are responsible for many times that number
going extinct each year
Endangered species- when numbers of
organisms get so low that extinction is possible
Threatened species- when an organism is at risk
of becoming endangered
5.1 Threats to Biodiversity


Habitat loss- habitats are often destroyed by
humans, causing the organisms to move or die
Habitat fragmentation- when wilderness areas are
divided, usually by human interference





Increases extinction of local species
Disrupts ecological processes
Increases risk of fire
Allows for invasion of unwanted or exotic species
Changes overall biodiversity
5.1 More Threats to Biodiversity

Edge effects- different organisms live on the edge
of habitats and have different conditions


Habitat destruction changes the edge of an ecosystem
Habitat Degradation- the damage to a habitat by
pollution


Water pollution-degrades aquatic habitats
Land pollution- degrades land by trash or introduction of
toxins to the soil, which move into the plants, and then the
animals
5.1 Exotic Species

New species are introduced into areas,
sometimes on purpose, sometimes on
accident


These species often interfere with the niche of
natural species, which disrupts the ecosystem
Exotic species often quickly overpopulate an
area and cause the native species to die out
5.2 Conservation Biology

Conservation biology- the study and
implementation of methods to protect
biodiversity


Natural resource conservation- focus on saving
natural resources such as sunlight, water, air,
soil, plants and animals
Species conservation- focus on saving animal
and plant species
5.2 Endangered Species

The US Endangered Species Act was
passed in 1973 to protect species that were
at risk of becoming extinct

This made it illegal to harm any of these species


Harm includes damaging or removing other parts
of the ecosystem where these species live
The CITES (Convention on International
trade in Endangered Species) protects
endangered species in more than 120
countries around the world
5.2 Habitat Preservation

The US has started numerous habitat
conservation programs to ensure that
species have a safe place to live

National parks & preserves were created as part
of this program


Examples include Yellowstone, Big Cypress,
Crater Lake, Big Bend & Sequoia National Parks
Habitat Corridors have also been created that
preserve migratory routes so animals can travel
between wilderness areas
5.2 Involvement of Humans

Sustainable Use- a philosophy that people
use natural resources while still maintaining
the ecosystem


People do not use more than can be regenerated
in the amount of time between harvests
This prevents us from overusing a resource and
causing it to become unavailable
5.2 Species Preservation

Reintroduction programs- release
organisms back into their natural habitat


These organisms are often grown in captivity
(held by people)
This is most successful when organisms are
reintroduced into a similar habitat to their original,
but is not the original (the original is usually
damaged)