Download Species Diversity


Describe the diversity of species types on
Earth, relating the difference between known
numbers and estimated numbers.

List and describe three levels of biodiversity.

Explain four ways in which biodiversity is
important to ecosystems.

Analyze the potential value of a single
species.
Why are some species better suited for
certain habitats than others? Why might a
species become less well suited for its habitat
over time? What must the species do if it is
no longer well suited for its habitat? - Write in
complete sentences. At least 5 lines.

Biodiversity – short for “biological diversity,” refers to
the number of different species in an area

Certain areas of the planet have an extraordinary
variety of species; i.e. the tropical rainforest

Relationships between species are complex so it is
important that we preserve biodiversity for our own
survival

To understand biodiversity we must identify
all of the species that exist on Earth. This is a
never ending task!

The known number of species is 1.7 million,
mostly insects.

Most scientists estimate there are about 10
million species. Many unidentified species
may be in the ocean or in remote wilderness.

Levels of Diversity:
 Species Diversity – number of different species in an area;
also known as biodiversity
 Ecosystem Diversity – variety of habitats, communities,
and ecological processes
 Genetic Diversity – all of the different genes contained by
the members of a population
▪ Gene – a piece of DNA that codes for a specific trait that
can be inherited by an organism’s offspring

Species Are Connected to Ecosystems

A healthy ecosystem has balanced cycles of energy and
nutrients. Species are part of these cycles.

Species have important roles in their ecosystems and either
depend on or are depended upon by one or more other
species. When one species disappears it might have serious
implications for the ecosystem.
 Check Your Understanding: We have learned about several cycles
(food webs, carbon cycle, nitrogen cycle). Give a few examples of how
organisms are part of these cycles.

Keystone Species – a species that is clearly
critical to the functioning of an ecosystem.
The ecosystem changes or collapses with out
this species.

Example of Keystone Species:
 Sea Otter – sea otter prey on sea urchin. Without
sea otter the urchin population grows out of control
and destroys the kelp bed ecosystem

Genetic diversity is critical to species survival.
It increases a species chance for survival
environmental changes.

Small, isolated populations are less likely to
survive changes.

We use other organisms for food, clothing,
shelter, and medicine.
 Check Your Understanding: Give some examples of
other species we use.

About 25% of the drugs prescribed in the
United States come from plants. There may
be other medicine that can come from plants
we have not yet discovered.

Reasons Why We Should Preserve
Biodiversity:
 Ethics – Species have the right to exist
 Aesthetics – Organisms and wildlife are beautiful
so they should be preserved
 Recreation – We should preserve species so we
have places to camp and hike. Ecotourism is
tourism that happens in ecologically unique areas.

Define and give examples of endangered and threatened
species.

Describe several ways that species are being threatened with
extinction globally.

Explain which types of threats are having the largest impact
on biodiversity.

List areas of the world that have high levels of biodiversity
and many threats to species.

Compare the amount of biodiversity in the United States to
that of the rest of the world.

It is estimated that between 1800 and 2100, up to
25% of all species on Earth may have become
extinct.

Species Prone to Extinction
 Endangered Species – a species that is likely to become
extinct if protective measures are not taken immediately
 Threatened Species – a species that has declining
populations and is likely to become endangered

Habitat Destruction and Fragmentation
 As our population grows we build more homes and use
more resources. This results in the destruction of habitats
or fragmentation. Fragmentation is when we break a
habitat up into smaller parts. This is a problem for
organism that require a large territory.

Invasive Exotic Species
 Exotic species are species that are not native to a
particular region. These are many times brought to the
new area by humans. These species may become
invasive, meaning they take over, because they have no
predators to control their populations.

Harvesting, Hunting, and Poaching
 Excessive hunting and harvesting of species can
also lead to extinction. Many countries now have
laws to regulate hunting, fishing, and harvesting.
However, poaching, which is illegal hunting of a
species, still happens frequently.

Pollution
 Pesticides, cleaning agents, drugs, and other
chemicals used by humans can affect the food
web.

Endemic Species – species that are native to
and found only within a limited area

Tropical Rain Forest
 Remaining tropical rain forest is less than 7% of
the Earth’s surface. However, scientists estimate
that over half of the world’s species live there!

Coral Reefs and Coastal Ecosystems
 Coral reefs occupy only a small fraction of the marine
environment yet contain a majority of the biodiversity
there. They also provide food and tourism revenue.
Nearly 60% of the Earth’s coral reefs are threatened by
human activities like overfishing and pollution.

Islands
 Islands contain species that have specially evolved to live
on those islands. These species may not be found
anywhere else in the world.

The most threatened areas of high species
diversity have been labeled biodiversity
hotspots.

Most of these hot spots have lost at least 70%
of their original vegetation.

Hotspots are mostly tropical rain forests,
coastal areas, and islands.

Biodiversity hotspots in the United States
include the Florida Everglades, the California
coastal region, Hawaii, the Midwestern
prairies, and forests of the Pacific Northwest.