Copyright Pearson Prentice Hall BIOLOGY CHAPTER 6, SECTIONS 3-4 (edited for Keystone emphasis) SECTION 3. BIODIVERSITY © Sun Star/Stock Photos Hawaii Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Value of Biodiversity Biological diversity, or biodiversity, is the sum total of the genetically based variety of all organisms in an area (or in the entire biosphere). One important aspect is the number of different species. Ecosystem diversity includes the variety of habitats, communities, and ecological processes in the living world. Copyright Pearson Prentice Hall

THE VALUE OF BIODIVERSITY Biodiversity is one of Earth's greatest natural resources. Species of many kinds have provided us with foods, industrial products, and medicines—including painkillers, antibiotics, heart drugs, and anticancer drugs. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Threats to Biodiversity Human activity can reduce biodiversity by: altering habitats removing or reducing a population hunting species to extinction introducing toxic compounds into food webs introducing foreign species to new environments Copyright Pearson Prentice Hall

THREATS TO BIODIVERSITY Extinction occurs when a species disappears from all or part of its range. A species whose population size is declining in a way that places it in danger of extinction is called an endangered species. As the population of an endangered species declines, the species loses genetic diversity. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Habitat Alteration When land is developed, natural habitats may be destroyed. Development often splits ecosystems into pieces, a process called habitat fragmentation. The smaller a species’ habitat is, the more vulnerable the species is to further disturbance. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Habitat Alteration Examples of changes that can eliminate habitats: Eutrophication of lakes (overgrowth due to excessive nutrients, such as algal blooms) Deforestation of wooded area Rising sea levels Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Pollution Many forms of pollution can threaten biodiversity. One of the most serious problems occurs when toxic compounds accumulate in the tissues of organisms. DDT, one of the first pesticides, is a good example of this. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall POLLUTION For a long time DDT was considered harmless, and it drained into rivers and streams in low concentrations. However, DDT has two hazardous properties: It is nonbiodegradable, which means that it cannot be broken down by organisms. Once DDT is picked up by organisms, it cannot be eliminated from their bodies. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall POLLUTION When DDT enters food webs, it undergoes biological magnfication. In biological magnification, concentrations of a harmful substance increase in organisms at higher trophic levels in a food chain or food web. In 1962, biologist Rachel Carson wrote Silent Spring, which alerted people to the dangers of biological magnification. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Magnification of DDT Concentration Pollution Magnification of DDT Concentration In the process of biological magnification, the concentration of a pollutant such as DDT—represented here by orange dots—is multiplied as it passes up the food chain from producers to consumers. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall POLLUTION The widespread use of DDT threatened populations of many animals—especially fish-eating birds like the bald eagle—with extinction. By the early 1970s, DDT was banned in the U.S. and in most other industrialized countries; as a result, affected bird populations have recovered. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Introduced Species Another threat to biodiversity comes from plants and animals that humans transport around the world either accidentally or intentionally. Invasive species are introduced species that reproduce rapidly because their new habitat lacks the predators that would control their population. Copyright Pearson Prentice Hall

The introduced species are also referred to as nonnative species. The species already present are called native or endemic. Ex. - a small fish, the round goby, was first reported in Pennsylvania waters in 1996. It is competing with similar endemic fish, such as the mottled sculpin.

Some have been released deliberately. INTRODUCED SPECIES Some endemic species arrive accidentally on ships from other parts of the world. Some have been released deliberately. Some may have been pets that were released.

Copyright Pearson Prentice Hall INTRODUCED SPECIES Nonnative species use more of the ecosystem’s resources. They may also reduce other populations directly through predation. Hundreds of invasive species—including zebra mussels in the Great Lakes and the leafy spurge across the Northern Great Plains—are already causing ecological problems in the United States. Copyright Pearson Prentice Hall

SECTION 4. CHARTING A COURSE FOR THE FUTURE Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Researchers are gathering data to monitor and evaluate the effects of human activities on important systems in the biosphere. Two of these systems are: the ozone layer high in the atmosphere the global climate system Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall OZONE DEPLETION Ozone in the atmosphere protects the surface from ultraviolet (UV) radiation Exposure to UV can: cause cancer damage eyes decrease organisms' resistance to disease damage plant leaf tissue and phytoplankton in the oceans Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall OZONE DEPLETION In the 1970s, scientists discovered a hole in the ozone layer over Antarctica. After it was first discovered, the ozone hole grew larger. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall OZONE DEPLETION Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall OZONE DEPLETION Ozone depletion was caused by reactions with CFCs (chlorofluorocarbons) released into the atmosphere. CFCs were once widely used: as propellants in aerosol cans as coolant in refrigerators, freezers, and air conditioners in the production of plastic foams The U.S. and other nations began reducing the use of CFCs in 1987, and eventually banned them. Copyright Pearson Prentice Hall

Ozone Depletion

Global Climate Change The term used to describe the increase in the average temperature of the biosphere is global warming. Burning of fossil fuels is increasing the content of carbon dioxide in the atmosphere.

GLOBAL WARMING As discussed earlier, carbon dioxide is a greenhouse gas, trapping heat in the atmosphere. The increase in carbon dioxide has led to an increase in world temperatures.

GLOBAL WARMING http://www.iflscience.com/environment/hottest-year-record-signals-global-warming-alive-and-well

Consequences of global warming: Disruption of ecosystems - plants and animals face temperatures for which they are not adapted Sea level is rising, due to melting ice caps plus expansion of the ocean water. This floods coastal areas with unique ecosystems. Increased floods, droughts, and severe storms. Droughts can lead to wildfires