Biology.ppt

1、Copyright Pearson Prentice Hall,Biology,Copyright Pearson Prentice Hall,6-3 Biodiversity,Copyright Pearson Prentice Hall,The Value of Biodiversity,The Value of Biodiversity Biological diversity, or biodiversity, is the sum total of the genetically based variety of all organisms in the biosphere. Eco

2、system diversity includes the variety of habitats, communities, and ecological processes in the living world.,Copyright Pearson Prentice Hall,The Value of Biodiversity,Species diversity is the number of different species in the biosphere. Genetic diversity is the sum total of all the different forms

3、 of genetic information carried by all organisms living on Earth today.,Copyright Pearson Prentice Hall,The Value of Biodiversity,Why is biodiversity important?,Copyright Pearson Prentice Hall,The Value of Biodiversity,Biodiversity is one of Earths greatest natural resources. Species of many kinds h

4、ave provided us with foods, industrial products, and medicinesincluding painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs.,Copyright Pearson Prentice Hall,Threats to Biodiversity,What are the current threats to biodiversity?,Copyright Pearson Prentice Hall,Threats to Biodi

5、versity,Threats to Biodiversity Human activity can reduce biodiversity by: altering habitats 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 speci

6、es 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,Habitat

7、 Alteration,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 H

8、all,Demand for Wildlife Products,Demand for Wildlife Products Throughout history, humans have pushed some animal species to extinction by hunting them for food or other products. Today, in the U.S., endangered species are protected from hunting.,Copyright Pearson Prentice Hall,Demand for Wildlife Pr

9、oducts,The Convention on International Trade in Endangered Species, CITES, bans international trade in products derived from endangered species.,Copyright Pearson Prentice Hall,Pollution,Pollution Many forms of pollution can threaten biodiversity. One of the most serious problems occurs when toxic c

10、ompounds accumulate in the tissues of organisms. DDT, one of the first pesticides, is a good example of this.,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

11、: 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,Pollution,When DDT enters food webs, it undergoes biological magnfication. In biological magnification, con

12、centrations 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,Pollution,Magnification of DDT Concent

13、ration,Copyright Pearson Prentice Hall,Pollution,Magnification of DDT Concentration,Copyright Pearson Prentice Hall,Pollution,Magnification of DDT Concentration,Copyright Pearson Prentice Hall,Pollution,Magnification of DDT Concentration,Copyright Pearson Prentice Hall,Pollution,Magnification of DDT

14、 Concentration,Copyright Pearson Prentice Hall,Pollution,Magnification of DDT Concentration,Copyright Pearson Prentice Hall,Pollution,The widespread use of DDT threatened populations of many animalsespecially fish-eating birds like the bald eaglewith extinction. By the early 1970s, DDT was banned in

15、 the U.S. and in most other industrialized countries; as a result, affected bird populations have recovered.,Copyright Pearson Prentice Hall,Introduced Species,Introduced Species Another threat to biodiversity comes from plants and animals that humans transport around the world either accidentally o

16、r 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,Introduced Species,Hundreds of invasive speciesincluding zebra mussels in the Great Lakes and the leafy s

17、purge across the Northern Great Plainsare already causing ecological problems in the United States.,Copyright Pearson Prentice Hall,Conserving Biodiversity,Conserving BiodiversityConservation is the wise management of natural resources, including the preservation of habitats and wildlife.,Copyright

18、Pearson Prentice Hall,Conserving Biodiversity,Strategies for Conservation Many conservation efforts are aimed at managing individual species to keep them from becoming extinct.,Copyright Pearson Prentice Hall,Conserving Biodiversity,What is the goal of conservation biology?,Copyright Pearson Prentic

19、e Hall,Conserving Biodiversity,Conservation efforts focus on protecting entire ecosystems as well as single species. Protecting an ecosystem will ensure that the natural habitats and the interactions of many different species are preserved at the same time.,Copyright Pearson Prentice Hall,Conserving

20、 Biodiversity,Conservation Challenges Protecting resources for the future can require people to change the way they earn their living today. Conservation regulations must be informed by solid research and must try to maximize benefits while minimizing economic costs.,Copyright Pearson Prentice Hall,

21、6-3,Copyright Pearson Prentice Hall,6-3,The type of biodiversity that includes the inheritance information carried by the Earths organisms is called biological magnification. ecological diversity. genetic diversity. species diversity.,Copyright Pearson Prentice Hall,6-3,Populations of invasive speci

22、es tend to decrease. increase rapidly. remain constant. increase, then decrease.,Copyright Pearson Prentice Hall,6-3,The wise management of natural resources, including the preservation of habitats and wildlife, is known as biodiversity. conservation. habitat alteration. ecosystem diversity.,Copyrig

23、ht Pearson Prentice Hall,6-3,By focusing on protecting specific ecosystems, biologists hope to preserve global biodiversity. biological magnification. invasive species. habitat fragmentation.,Copyright Pearson Prentice Hall,6-3,In a food pyramid, biological magnification results in the increased amount of a toxic substance in organisms at the lowest level. increased amount of a toxic substance in organisms at the highest level. decreased number of levels in the food pyramid. increased amount of a toxic substance in the surrounding air or water.,END OF SECTION,