1. Concept 56.1: Human activities threaten Earth’s biodiversity
Rates of species extinction are difficult to determine under natural conditions
The high rate of species extinction is largely a result of ecosystem degradation by humans
Humans are threatening Earth’s biodiversity

2. Three Levels of Biodiversity
Biodiversity has three main components:
Genetic diversity
Species diversity
Ecosystem diversity

3. Genetic diversity in a vole population
Fig. 56-3
Genetic diversity in a vole population
Species diversity in a coastal redwood ecosystem
Figure 56.3 Three levels of biodiversity
Community and ecosystem diversity
across the landscape of an entire region

4. Genetic Diversity
Genetic diversity comprises genetic variation within a population and between populations

5. According to the U.S. Endangered Species Act:
Species Diversity
Species diversity is the variety of species in an ecosystem or throughout the biosphere
According to the U.S. Endangered Species Act:
An endangered species is “in danger of becoming extinct throughout all or a significant portion of its range”
A threatened species is likely to become endangered in the foreseeable future

6. Conservation biologists are concerned about species loss because of alarming statistics regarding extinction and biodiversity
Globally, 12% of birds, 20% of mammals, and 32% of amphibians are threatened with extinction

7. (a) Philippine eagle Fig. 56-4a
Figure 56.4 A hundred heartbeats from extinction
(a) Philippine eagle

8. (b) Yangtze River dolphin
Fig. 56-4b
Figure 56.4 A hundred heartbeats from extinction
(b) Yangtze River dolphin

9. (c) Javan rhinoceros Fig. 56-4c
Figure 56.4 A hundred heartbeats from extinction
(c) Javan rhinoceros

10. Ecosystem Diversity
Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere
More than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems

11. Biodiversity and Human Welfare
Human biophilia allows us to recognize the value of biodiversity for its own sake
Species diversity brings humans practical benefits

12. Benefits of Species and Genetic Diversity
In the United States, 25% of prescriptions contain substances originally derived from plants
For example, the rosy periwinkle contains alkaloids that inhibit cancer growth

13. Fig. 56-6
Figure 56.6 The rosy periwinkle (Catharanthus roseus), a plant that saves lives

14. The loss of species also means loss of genes and genetic diversity
The enormous genetic diversity of organisms has potential for great human benefit

15. Some examples of ecosystem services:
Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life
Some examples of ecosystem services:
Purification of air and water
Detoxification and decomposition of wastes
Cycling of nutrients
Moderation of weather extremes

16. Three Threats to Biodiversity
Most species loss can be traced to three major threats:
Habitat destruction
Introduced species
Overexploitation

17. Habitat Loss
Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere
In almost all cases, habitat fragmentation and destruction lead to loss of biodiversity
For example
In Wisconsin, prairie occupies <0.1% of its original area
About 93% of coral reefs have been damaged by human activities

18. Fig. 56-7
Figure 56.7 Habitat fragmentation in the foothills of Los Angeles

19. Introduced Species
Introduced species are those that humans move from native locations to new geographic regions
Without their native predators, parasites, and pathogens, introduced species may spread rapidly
Introduced species that gain a foothold in a new habitat usually disrupt their adopted community

20. Sometimes humans introduce species by accident, as in case of the brown tree snake arriving in Guam as a cargo ship “stowaway”

21. Fig. 56-8a
Figure 56.8 Two introduced species
(a) Brown tree snake

22. Humans have deliberately introduced some species with good intentions but disastrous effects
An example is the introduction of kudzu in the southern United States

23. Overexploitation
Overexploitation is human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound
Overexploitation by the fishing industry has greatly reduced populations of some game fish, such as bluefin tuna

24. Fig. 56-9
Figure 56.9 Overexploitation

25. DNA analysis can help conservation biologists to identify the source of illegally obtained animal products

26. Concept 56.4: Restoration ecology attempts to restore degraded ecosystems to a more natural state
Given enough time, biological communities can recover from many types of disturbances
Restoration ecology seeks to initiate or speed up the recovery of degraded ecosystems
A basic assumption of restoration ecology is that most environmental damage is reversible
Two key strategies are bioremediation and augmentation of ecosystem processes

27. (a) In 1991, before restoration
Fig a
Figure A gravel and clay mine site in New Jersey before and after restoration
(a) In 1991, before restoration

28. (b) In 2000, near the completion of restoration
Fig b
Figure A gravel and clay mine site in New Jersey before and after restoration
(b) In 2000, near the completion of restoration

29. Bioremediation
Bioremediation is the use of living organisms to detoxify ecosystems
The organisms most often used are prokaryotes, fungi, or plants
These organisms can take up, and sometimes metabolize, toxic molecules

30. (a) Unlined pits filled with wastes containing uranium
Fig a
Figure Bioremediation of groundwater contaminated with uranium at Oak Ridge National Laboratory, Tennessee
(a) Unlined pits filled with wastes containing uranium

31. soluble uranium (µM) Concentration of
Fig b 6 5 4
soluble uranium (µM)
Concentration of 3 2 1
Figure Bioremediation of groundwater contaminated with uranium at Oak Ridge National Laboratory, Tennessee 50
100
150
200
250
300
350
400
Days after adding ethanol
(b) Uranium in groundwater

32. Biological Augmentation
Biological augmentation uses organisms to add essential materials to a degraded ecosystem
For example, nitrogen-fixing plants can increase the available nitrogen in soil

33. Exploring Restoration
The newness and complexity of restoration ecology require that ecologists consider alternative solutions and adjust approaches based on experience