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Transcript of Chapter 55
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 55Chapter 55
Conservation Biology and Restoration Ecology
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Important Information!
• I have not edited this ppt. You may go through it, but it does not have audio like the other ppts.
• You will still have a quiz on this chapter.
• Make sure to do the outline and if you want to go through this ppt, go for it!
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Overview: The Biodiversity Crisis
– Conservation biology integrates the following fields to conserve biological diversity at all levels
– Ecology
– Evolutionary biology
– Physiology
– Molecular biology
– Genetics
– Behavioral ecology
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• Restoration ecology applies ecological principles
– In an effort to return degraded ecosystems to conditions as similar as possible to their natural state
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• Tropical forests
– Contain some of the greatest concentrations of species
– Are being destroyed at an alarming rate
Figure 55.1
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• Throughout the biosphere, human activities
– Are altering ecosystem processes on which we and other species depend
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• Concept 55.1: Human activities threaten Earth’s biodiversity
• Rates of species extinction
– Are difficult to determine under natural conditions
• The current rate of species extinction is high
– And is largely a result of ecosystem degradation by humans
• Humans are threatening Earth’s biodiversity
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The Three Levels of Biodiversity
• Biodiversity has three main components
– Genetic diversity
– Species diversity
– Ecosystem diversity
Genetic diversity in a vole population
Species diversity in a coastal redwood ecosystem
Community and ecosystem diversityacross the landscape of an entire regionFigure 55.2
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Genetic Diversity
• Genetic diversity comprises
– The genetic variation within a population
– The genetic variation between populations
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Species Diversity
• Species diversity
– Is the variety of species in an ecosystem or throughout the biosphere
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• An endangered species
– Is one that is in danger of becoming extinct throughout its range
• Threatened species
– Are those that are considered likely to become endangered in the foreseeable future
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• Conservation biologists are concerned about species loss
– Because of a number of alarming statistics regarding extinction and biodiversity
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• Harvard biologist E. O. Wilson has identified the Hundred Heartbeat Club
– Species that number fewer than 100 individuals and are only that many heartbeats from extinction
(a) Philippine eagle
(b) Chinese river dolphin
(c) Javan rhinocerosFigure 55.3a–c
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Ecosystem Diversity
• Ecosystem diversity
– Identifies the variety of ecosystems in the biosphere
– Is being affected by human activity
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Biodiversity and Human Welfare
• Human biophilia
– Allows us to recognize the value of biodiversity for its own sake
• Species diversity
– Brings humans many practical benefits
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Benefits of Species and Genetic Diversity
• Many pharmaceuticals
– Contain substances originally derived from plants
Figure 55.4
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• The loss of species
– Also means the loss of genes and genetic diversity
• The enormous genetic diversity of organisms on Earth
– Has the potential for great human benefit
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Ecosystem Services
• Ecosystem services encompass all the processes
– Through which natural ecosystems and the species they contain help sustain human life on Earth
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• Ecosystem services include
– Purification of air and water
– Detoxification and decomposition of wastes
– Cycling of nutrients
– Moderation of weather extremes
– And many others
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Four Major Threats to Biodiversity
• Most species loss can be traced to four major threats
– Habitat destruction
– Introduced species
– Overexploitation
– Disruption of “interaction networks”
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Habitat Destruction
• Human alteration of habitat
– Is the single greatest threat to biodiversity throughout the biosphere
• Massive destruction of habitat
– Has been brought about by many types of human activity
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• Many natural landscapes have been broken up
– Fragmenting habitat into small patches
Figure 55.5
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• In almost all cases
– Habitat fragmentation and destruction leads to loss of biodiversity
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Introduced Species
• Introduced species
– Are those that humans move from the species’ native locations to new geographic regions
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• Introduced species that gain a foothold in a new habitat
– Usually disrupt their adopted community(a) Brown tree snake, intro- duced to Guam in cargo
(b) Introduced kudzu thriving in South CarolinaFigure 55.6a, b
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Overexploitation
• Overexploitation refers generally to the human harvesting of wild plants or animals
– At rates exceeding the ability of populations of those species to rebound
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• The fishing industry
– Has caused significant reduction in populations of certain game fish
Figure 55.7
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Disruption of Interaction Networks
• The extermination of keystone species by humans
– Can lead to major changes in the structure of communities
Figure 55.8
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• Concept 55.2: Population conservation focuses on population size, genetic diversity, and critical habitat
• Biologists focusing on conservation at the population and species levels
– Follow two main approaches
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Small-Population Approach
• Conservation biologists who adopt the small-population approach
– Study the processes that can cause very small populations finally to become extinct
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The Extinction Vortex
• A small population is prone to positive-feedback loops
– That draw the population down an extinction vortex
Smallpopulation
InbreedingGenetic
drift
Lower reproduction
Higher mortality
Loss ofgenetic
variabilityReduction inindividual
fitness andpopulationadaptability
Smallerpopulation
Figure 55.9
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• The key factor driving the extinction vortex
– Is the loss of the genetic variation necessary to enable evolutionary responses to environmental change
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Case Study: The Greater Prairie Chicken and the Extinction Vortex
• Populations of the greater prairie chicken
– Were fragmented by agriculture and later found to exhibit decreased fertility
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• As a test of the extinction vortex hypothesis
– Scientists imported genetic variation by transplanting birds from larger populations
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• The declining population rebounded
– Confirming that it had been on its way down an extinction vortex
EXPRIMENT Researchers observed that the population collapse of the greater prairie chicken was mirrored in a reduction in fertility, as measured by the hatching rate of eggs. Comparison of DNA samples from the Jasper County, Illinois, population with DNA from feathers in museum specimens showed that genetic variation had declined in the study population. In 1992, researchers began experimental translocations of prairie chickens from Minnesota, Kansas, and Nebraska in an attempt to increase genetic variation.
RESULTS After translocation (blue arrow), the viability of eggs rapidly improved, and the population rebounded.
CONCLUSION The researchers concluded that lack of genetic variation had started the Jasper County population of prairie chickens down the extinction vortex.
Num
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(b) Hatching rate
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301970-74 1975-79 1980-84 1985-89 1990 1993-97
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Figure 55.10
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Minimum Viable Population Size
• The minimum viable population (MVP)
– Is the minimum population size at which a species is able to sustain its numbers and survive
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• A population viability analysis (PVA)
– Predicts a population’s chances for survival over a particular time
– Factors in the MVP of a population
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Effective Population Size
• A meaningful estimate of MVP
– Requires a researcher to determine the effective population size, which is based on the breeding size of a population
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Case Study: Analysis of Grizzly Bear Populations
• One of the first population viability analyses
– Was conducted as part of a long-term study of grizzly bears in Yellowstone National Park
Figure 55.11
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• This study has shown that the grizzly bear population
– Has grown substantially in the past 20 yearsN
umb
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f in
div
idua
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150
100
50
01973 1982 1991 2000
Females with cubs
Cubs
YearFigure 55.12
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Declining-Population Approach
• The declining-population approach
– Focuses on threatened and endangered populations that show a downward trend, regardless of population size
– Emphasizes the environmental factors that caused a population to decline in the first place
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Steps for Analysis and Intervention
• The declining-population approach
– Requires that population declines be evaluated on a case-by-case basis
– Involves a step-by-step proactive conservation strategy
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Case Study: Decline of the Red-Cockaded Woodpecker
• Red-cockaded woodpeckers
– Require specific habitat factors for survival
– Had been forced into decline by habitat destruction
(a) A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine.
(b) Forest that can sustain red-cockaded woodpeckers has low undergrowth.
(c) Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds.Figure 55.13a–c
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• In a study where breeding cavities were constructed
– New breeding groups formed only in these sites
• On the basis of this experiment
– A combination of habitat maintenance and excavation of new breeding cavities has enabled a once-endangered species to rebound
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Weighing Conflicting Demands
• Conserving species often requires resolving conflicts
– Between the habitat needs of endangered species and human demands
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• Concept 55.3: Landscape and regional conservation aim to sustain entire biotas
• In recent years, conservation biology
– Has attempted to sustain the biodiversity of entire communities, ecosystems, and landscapes
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• One goal of landscape ecology, of which ecosystem management is part
– Is to understand past, present, and future patterns of landscape use and to make biodiversity conservation part of land-use planning
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Landscape Structure and Biodiversity
• The structure of a landscape
– Can strongly influence biodiversity
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Fragmentation and Edges
• The boundaries, or edges, between ecosystems
– Are defining features of landscapes
(a) Natural edges. Grasslands give way to forest ecosystems in Yellowstone National Park.
(b) Edges created by human activity. Pronounced edges (roads) surround clear-cuts in this photograph of a heavily logged rain forest in Malaysia.Figure 55.14a, b
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• As habitat fragmentation increases
– And edges become more extensive, biodiversity tends to decrease
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• Research on fragmented forests has led to the discovery of two groups of species
– Those that live in forest edge habitats and those that live in the forest interior
Figure 55.15
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Corridors That Connect Habitat Fragments
• A movement corridor
– Is a narrow strip of quality habitat connecting otherwise isolated patches
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• In areas of heavy human use
– Artificial corridors are sometimes constructed
Figure 55.16
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• Movement corridors
– Promote dispersal and help sustain populations
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Establishing Protected Areas
• Conservation biologists are applying their understanding of ecological dynamics
– In establishing protected areas to slow the loss of biodiversity
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• Much of the focus on establishing protected areas
– Has been on hot spots of biological diversity
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Finding Biodiversity Hot Spots
• A biodiversity hot spot is a relatively small area
– With an exceptional concentration of endemic species and a large number of endangered and threatened species
Terrestrial biodiversity hot spots
Equator
Figure 55.17
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• Biodiversity hot spots are obviously good choices for nature reserves
– But identifying them is not always easy
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Philosophy of Nature Reserves
• Nature reserves are biodiversity islands
– In a sea of habitat degraded to varying degrees by human activity
• One argument for extensive reserves
– Is that large, far-ranging animals with low-density populations require extensive habitats
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• In some cases
– The size of reserves is smaller than the actual area needed to sustain a population
Biotic boundary forshort-term survival;MVP is 50 individuals.
Biotic boundary forlong-term survival;MVP is 500 individuals.
Grand TetonNational Park
Wyo
min
g
Idah
o
43
42
41
40
0 50 100
Kilometers
Snake R.
Yellowstone National Park
Shoshone R.
Montana
Wyoming
Montana
Idaho
Mad
ison
R.
Gal
latin
R.
Yellowstone R.
Figure 55.18
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Zoned Reserves
• The zoned reserve model recognizes that conservation efforts
– Often involve working in landscapes that are largely human dominated
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• Zoned reserves
– Are often established as “conservation areas”
(a) Boundaries of the zoned reserves are indicated by black outlines.
(b) Local schoolchildren marvel at the diversity of life in one of Costa Rica’s reserves.
Nicaragua
CostaRica
Pan
amaNational park land
Buffer zone
PACIFIC OCEAN
CARIBBEAN SEA
Figure 55.19a, b
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• Some zoned reserves in the Fiji islands are closed to fishing
– Which actually helps to improve fishing success in nearby areas
Figure 55.20
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• Concept 55.4: Restoration ecology attempts to restore degraded ecosystems to a more natural state
• The larger the area disturbed
– The longer the time that is required for recovery
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• Whether a disturbance is natural or caused by humans
– Seems to make little difference in this size-time relationship
Rec
over
y tim
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ears
)(lo
g sc
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104
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103 102 101 1 10 100 1,000 104
Natural disasters
Human-caused disasters
Natural OR human-caused disasters
Meteorstrike
Groundwaterexploitation
Industrialpollution
Urbanization Salination
Modernagriculture Flood
Volcaniceruption
Acidrain
Forestfire
Nuclearbomb
Tsunami
Oilspill
Slash& burn
Land-slide
Treefall
Lightningstrike
Spatial scale (km2)(log scale)
Figure 55.21
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• One of the basic assumptions of restoration ecology
– Is that most environmental damage is reversible
• Two key strategies in restoration ecology
– Are bioremediation and augmentation of ecosystem processes
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Bioremediation
• Bioremediation
– Is the use of living organisms to detoxify ecosystems
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Biological Augmentation
• Biological augmentation
– Uses organisms to add essential materials to a degraded ecosystem
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Exploring Restoration
• The newness and complexity of restoration ecology
– Require scientists to consider alternative solutions and adjust approaches based on experience
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• Exploring restoration worldwide
Truckee River, Nevada. Kissimmee River, Florida.
Equator
Figure 55.22
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Tropical dry forest, Costa Rica. Succulent Karoo, South Africa.
Rhine River, Europe. Coastal Japan.Figure 55.22
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• Concept 55.5: Sustainable development seeks to improve the human condition while conserving biodiversity
• Facing increasing loss and fragmentation of habitats
– How can we best manage Earth’s resources?
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Sustainable Biosphere Initiative
• The goal of this initiative is to define and acquire the basic ecological information necessary
– For the intelligent and responsible development, management, and conservation of Earth’s resources
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Case Study: Sustainable Development in Costa Rica
• Costa Rica’s success in conserving tropical biodiversity
– Has involved partnerships between the government, other organizations, and private citizens
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• Human living conditions in Costa Rica
– Have improved along with ecological conservationIn
fan
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live
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Life expectancyInfant mortality
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Figure 55.23
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Biophilia and the Future of the Biosphere
• Our modern lives
– Are very different from those of early humans who hunted and gathered and painted on cave walls
(a) Detail of animals in a Paleolithic mural, Lascaux, FranceFigure 55.24a
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• But our behavior
– Reflects remnants of our ancestral attachment to nature and the diversity of life, the concept of biophilia
(b) Biologist Carlos Rivera Gonzales examining a tiny tree frog in PeruFigure 55.24b
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• Our innate sense of connection to nature
– May eventually motivate a realignment of our environmental priorities