• Biodiversity refers to the variety of species in a specific area.

• The simplest and most common measure of biodiversity is the number of different species that live in a certain area.

Biological DiversityBiological Diversity

• Think Pair Share: Identify the area with the most/least biodiversity

• Areas around the world differ in biodiversity.

• Biodiversity increases as you move toward the equator.

Where is biodiversity found?Where is biodiversity found?• Think Pair Share: what part of the planet would

you expect to find the most biodiversity? The least?.

Where is biodiversity found?Where is biodiversity found?• Tropical regions contain two-thirds of all land

species on Earth.

• The richest environments for biodiversity all seem to be warm places: tropical rain forests, coral reefs, and large tropical lakes.

Importance to natureImportance to nature• Living things are interdependent.

• Living things can be niches for other living things.

• Populations are adapted to live together in communities.

Importance to natureImportance to nature

• Scientists now know that if a species is lost from an ecosystem, the loss may have consequences for other living things in the area.

Biodiversity brings stabilityBiodiversity brings stability• More biodiversity = more stability.

• A pest could destroy all the corn in a farmer’s field, but it would be more difficult for it to destroy all the corn (or representative species) in a rain forest.

Importance to peopleImportance to people

• Humans depend on other organisms for their needs.

• only a few species of plants and animals supply the major portion of the food eaten by the human population.

• Biodiversity could help breeders produce additional food crops.

Importance to peopleImportance to people

• Preserving biodiversity ensures there will be a supply of living things, some of which may provide future drugs.

Penicillium

Loss of BiodiversityLoss of Biodiversity

• Extinction: disappearance of a species when the last of its members dies.

• a natural process Earth has had several mass extinctions during its history.

Loss of BiodiversityLoss of Biodiversity

• estimated that background extinction ~ 1 – 10 species/yr.

• !! current rate exceeds that by many times.

• always a level of natural extinction (background extinction)

Loss of BiodiversityLoss of Biodiversity• endangered species: when numbers so low

extinction is possible.

• When a species is likely to become endangered, is threatened.

Loss of BiodiversityLoss of Biodiversity

Habitat lossHabitat loss• One biggest reasons for

decline in biodiversity.

Threats to BiodiversityThreats to Biodiversity

Habitat fragmentationHabitat fragmentation

• the separation of wilderness areas from other wilderness areas.

Habitat fragmentationHabitat fragmentation

Habitat fragmentation contributes to:

• increased extinction.

• disruption of ecological processes.

• changes in biodiversity.

• invasions by exotic species.

• risk of fire.

Habitat fragmentationHabitat fragmentation

• smaller fragment = less biodiversity.

• Geographic isolation can → genetic isolation.

• makes recolonizing difficult.

Edge effectEdge effect• Conditions at the edge of a habitat are different

from those within.

• When an edge changes, animals might migrate because there isn’t enough space from which to gather food.

• Organisms might be exposed to new organisms or abiotic conditions (predators, prey, temperature, light, plant life)

• habitat degradation the damage to a habitat by pollution.

• air, water, & land.

Habitat degradationHabitat degradation

• Pollutants enter atmosphere in many ways—volcanic eruptions, forest fires.

Habitat degradationHabitat degradation

• Burning fossil fuels is source of air pollutants like sulfur dioxide.

• Acid precipitation—rain, snow, sleet, and fog with low pH values—linked to damage of forests and lakes.

Habitat degradationHabitat degradation• ozone layer absorbs

sun’s ultraviolet waves reducing the UV radiation reaching Earth’s surface.

Click image to view movie.

• synthetic chemicals like chlorofluorocarbons (CFC’s) react with ozone to create “holes” in its layer.

Water pollutionWater pollution• Water pollution degrades aquatic habitats in

streams, rivers, lakes, and oceans.

• can affect aquatic life.

Water pollutionWater pollution

• Excess fertilizers and animal wastes are carried by rain into streams and lakes.

• The sudden availability of nutrients causes algal blooms, the excessive growth of algae, which decreases oxygen levels.

Land pollutionLand pollution• solid waste, cans,

bottles, paper, plastic, metals, spoiled food, cleaners, or paint may contain chemicals that leach into soil and ground water.

Click image to view movie.

• Solution: Recycling

Land pollution factsLand pollution facts

• The average American produces ~ 1.8 kg of solid waste daily.

• ~ 657 kg of waste/person/yr.

• some may decompose, most becomes solid waste buried in landfills.

Land pollutionLand pollution

• The use of pesticides and other chemicals can also lead to habitat degradation.

Exotic speciesExotic species

• People may introduce a new species to an ecosystem.

• can cause problems for native species.

Kudzu

Exotic speciesExotic species

• When exotic species are introduced, can grow faster because are not as vulnerable to local competitors or predators as native species.

• Example: exotic snakes in Florida

Question 1

The term that refers to the variety of species in a specific area is _________.

D. endangered species

C. biodiversity

B. conservation biology

A. ecology

The answer is C. The simplest measure of biodiversity is the number of different species that live in a certain area.

Question 2

Describe the possible effect on a biological community of removing one species.

Because living things are interdependent, removing a single species from a community can remove a food source or otherwise break symbiotic relationships causing remaining organisms to suffer. This decreases the stability of the ecosystem.

Question 3

When the population of a species begins to significantly decline in numbers, it is __________.

D. diverse

C. fragmented

B. extinct

A. threatened

The answer is A. When the population of a species is declining and likely to become endangered, it is said to be a threatened species.

Listing status Current Range

African elephant Mammals T Africa

*U.S. Fish & Wildlife Service Threatened and Endangered Species System (TESS)

Through the Fish and Wildlife Service, information is available to the public on all species threatened or endangered T, under Listing Status, refers to threatened. An E would indicate endangered.

GroupCommon NameScientific Name

Loxodonta africana

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