BiodiversityCHAPTER 5 LESSON 1 – P116-121

Biodiversity• The variety of life in an area that is determined by the number of

different species there

• The greater the biodiversity the more stable an ecosystem is

• As species become extinct, biodiversity decreases and so does the health of the ecosystem

• There are 3 types of biodiversity:• Genetic Diversity• Species Diversity• Ecosystem Diversity

Genetic Diversity• The variety of genes or inheritable traits in a

population

• Visible Traits• Color• Shape• Size

• Invisible Advantageous Traits• Resistance to diseases• Ability to recover from diseases• Ability to get energy from new food sources if old ones

disappear

Genetic Diversity• Increases a populations chance of survival during environmental

changes or disease

• Genetic differences may give some individuals advantages

Species Diversity• The number of different species and the relative amounts of each

species in a biological community

• A habit with many species present at healthy numbers has high species diversity

• Species diversity changes across ecosystems and biomes• Polar regions have low species diversity• Areas near the equator have high species diversity

Ecosystem Diversity• The variety of ecosystems that are present in the biosphere• Ecosystems include interacting populations and abiotic factors• Different abiotic factors support different types of life

• Tropical rainforest have abiotic factors necessary to support tropical bird species

• The loss of ecosystem diversity would likely result in a decrease in species diversity

The Importance of Biodiversity

Direct Economic Value• There are several reasons to preserve biodiversity

• Direct Resource Value• Organisms we use for food, clothing, medicine, energy, and shelter

• Direct Genetic Value• Organisms we do not use readily (wild species)• Provide sources of desirable traits• Possible transfer of desirable genes by genetic engineering

• Resistance to insects• Increased nutritional value• Resistance to spoilage

Direct Economic Value• Medicine• Many medicines today are derived from plants• Many species may have medicinal value that have not be

discovered yet

• Agriculture• The world’s food crops come from just a few species • Little genetic diversity• Transferring of genes by genetic engineering has helped

many crops

http://www.businessinsider.com/10-crops-that-feed-the-world-2011-9?op=1

Direct Economic Value• Example: Teosinte and Corn• Teosinte is a distant relative of the corn we eat• Teosinte is a wild plant with no direct resource value• Later scientists found that teosinte is disease-resistant against a viral

disease that was damaging corn crops• Using teosinte, scientists made disease-resistant corn varieties

• http://www.hhmi.org/biointeractive/breeding-corn-teosinte

Indirect Economic Value• A healthy biosphere provides many services to humans• Green plants make oxygen• Removal of carbon dioxide• Natural processes clean drinking water• Protect against floods and droughts• Generate and preserve fertile soils• Detoxify and decompose wasters• Regulate climate

• These advantages are difficult to attach economic value

NYC Watershed• In the 1990s NYC wanted to improve the

quality of its drinking water• NYC’s drinking water was supplied by the

Catskill and Delaware Watersheds that were highly polluted

• The city had two options:• 1. Build a new filtration system for 6 billion dollars• 2. Clean up and preserve the watersheds for 1.5 billion

dollars

• The answer was clear.• Often, preservation of a healthy ecosystem can

provide the same services as technology but at less expensive costs and long lasting results.

Aesthetic and Scientific Values• It is difficult to determine the economic value of having a beautiful and

healthy ecosystem• It’s also difficult to find the economic value of studying healthy ecosystem

and how to protect them.

Threats to Biodiversity

Extinction Rates• Many species become extinct because of natural processes like climate

change, other organisms, or natural disasters.• These occurred even before humans existed

• This natural gradual process of extinction is known as background extinction.• These types of extinctions are normal and not what scientists are concerned about.

Extinction Rates• Many scientists are worried about the recent increase in the rate of

extinction.• Some estimate the current rate of extinction is 1000 times the normal

background extinction rate.• Most of these extinctions are occurring near the equator.

Extinction Rates• Some scientists believe we are witnessing a period of

mass extinction.• A large percentage of living species become extinct in a short amount

of time• Scientists predict 1/3 to 2/3s of all plants and animals will become

extinct in the second half of the century.• The last mass extinction happened 65 million years ago when the last

remaining dinosaurs died out.

Extinction Rates• Island species are most vulnerable to extinction.• Many evolved with no natural predators• New nonnative species can bring diseases• Relatively small population sizes• Species rarely travel between islands

Factors That Threaten Biodiversity• Today’s current rate of extinction is different from past mass extinctions.

• Why is it special?

• After a mass extinction in the past, new species evolved and biodiversity recovered over time (several millions of years)

• Today, humans are changing the conditions on Earth faster than new traits can evolve to adapt

• Evolving species might not have the natural resources they need• Minerals, fossil fuels, nuclear energy, plants, animals, soil, clean water and air, solar energy

Factors That Threaten Biodiversity• 8 factors that threaten biodiversity:• 1. habitat loss• 2. destruction of habitat• 3. disruption of habitat• 4. overexploitation• 5. fragmentation of habitat• 6. Pollution• 7. Acid Rain• 8. Eutrophication

Overexploitation• The excessive use of species

that have economic value• Overhunting• Bison• Passenger pigeons• Ocelot• White rhinoceros

• Historically, overexploitation was the primary cause of species extinction.

Habitat loss• Destruction of Habitat• Clearing of rain forests• Over half of all species live in the tropical rain forest

Habitat loss• Disruption of Habitat• Factors that cause a decline of an important species• When one species plays a large role in an ecosystem, that species is

called a keystone species• California Sea Otter• Pisaster Starfish

Habitat loss• Fragmentation of habitat• The separation of an ecosystem into small pieces of land• Unable or unwilling to cross human barriers

Habitat loss• Fragmentation of habitat• Consequences:• Smaller land = fewer species it can support• Decreased genetic diversity• Less able to resist disease and respond to environmental

changes• Edge effect• Carving a large ecosystem into smaller pieces increases the

number of edges• Conditions change along the boundaries of an ecosystem• Temperature, wind, humidity

Pollution• Pollution changes the composition of air, soil, and water• Threaten biodiversity and global stability• Types:• Substances• Acid precipitation• Eutrophication• Introduced species

Pollution: Substance• Man-made chemicals • Pesticides (DDT) and industrial chemicals like (PCBs)

• Polluted drinking water• Eating other organisms that contain toxic substances• Some substances can be digested or excreted• Some substances accumulate in the tissues

• Harmful to organisms• DDT -> thin weak eggshells

Pollution: Substance• Biological Magnification• The increase of toxic substances in

organisms as you go up the tropic levels

Pollution: Acid Precipitation• When fossil fuels are burned sulfur dioxide and nitrogen dioxide are

released into the air• These compound react with water to form sulfuric acid and nitric acid• These acids fall to Earth as rain, sleet, or snow• Removes calcium, potassium, and other nutrients from the soil• Damages plant tissues and slows growth• High acid concentrations in lakes and rivers cause organisms to die

Pollution: Eutrophication• Fertilizers, animal waste, sewage, or other substances rich in nitrogen and

phosphorus flow into waterways causing extensive algae growth

• Algae use up the oxygen supply• Growth• Decomposition

• Other organisms suffocate

• Eutrophication can occur naturally

• Humans accelerate normal rates

Pollution: Introduced Species• Nonnative species are any species that has been transported to a

new habitat

• In their new habitats they lack natural predators, parasites, and composition for resources

• Often leads to increased reproduction

• When a nonnative species threatens the biodiversity of an area they are called invasive species