Transcript video slide - Biology Junction

Chapter 55
Conservation Biology and
Restoration Ecology
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
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
Figure 55.2
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Community and ecosystem diversity
across the landscape of an entire region
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
Figure 55.3a–c
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(c) Javan
rhinoceros
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, introduced to Guam
in cargo
Figure 55.6a, b
(b) Introduced kudzu thriving in South Carolina
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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 smallpopulation 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 positivefeedback loops
– That draw the population down an extinction
vortex
Small
population
Inbreeding
Genetic
drift
Lower
reproduction
Higher
mortality
Reduction in
individual
fitness and
population
adaptability
Figure 55.9
Smaller
population
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Loss of
genetic
variability
• 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
200
Number of male birds
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.
150
100
50
0
1970
RESULTS
After translocation (blue arrow), the viability of
eggs rapidly improved, and the population rebounded.
1975
1980
(a) Population dynamics
1985
1990
Year
1995
2000
100
CONCLUSION
The researchers concluded that lack of genetic
variation had started the Jasper County population of prairie
chickens down the extinction vortex.
Figure 55.10
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Eggs hatched (%)
90
80
70
60
50
40
30
1970-74 1975-79 1980-84 1985-89
Years
(b) Hatching rate
1990
1993-97
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 years
150
Females with cubs
Number of individuals
Cubs
100
50
0
1973
1991
1982
Figure 55.12
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Year
2000
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.
Figure 55.13a–c
(b) Forest that can
sustain red-cockaded
woodpeckers has
low undergrowth.
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(c) Forest that cannot sustain red-cockaded
woodpeckers has high, dense undergrowth that
impacts the woodpeckers’ access to feeding grounds.
• 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.
Figure 55.14a, b
(b) Edges created by human activity. Pronounced edges (roads)
surround clear-cuts in this photograph of a heavily logged rain
forest in Malaysia.
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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 lowdensity 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
0
50
100
Kilometers
42
Gallatin R.
Madison R.
43
Montana
Wyoming
Yellowstone
National
Park
Montana
Idaho
Shoshone R.
41
Grand Teton
National Park
Wyoming
Idaho
40
Figure 55.18
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Biotic boundary for
short-term survival;
MVP is 50 individuals.
Biotic boundary for
long-term survival;
MVP is 500 individuals.
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”
Nicaragua
Costa
Rica
National park land
Buffer zone
PACIFIC OCEAN
(a) Boundaries of the zoned reserves are indicated by black outlines.
Figure 55.19a, b
(b) Local schoolchildren marvel at the diversity of life in one of
Costa Rica’s reserves.
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CARIBBEAN SEA
• 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 sizetime relationship
104
Natural disasters
Recovery time (years)
(log scale)
Human-caused disasters
Natural OR humancaused disasters
1,000
Meteor
strike
Industrial
pollution
Groundwater
exploitation
Salination
Urbanization
Modern
Volcanic Acid
agriculture Flood eruption rain
100
Slash
& burn
Oil
spill
Forest Nuclear Tsunami
fire
bomb
Landslide
10
Tree
fall
Lightning
strike
1
103
102
101
1
10
Spatial scale (km2)
(log scale)
Figure 55.21
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100
1,000
104
• 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
Equator
Figure 55.22
Truckee River, Nevada.
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Kissimmee River, Florida.
Figure 55.22
Tropical dry forest, Costa Rica.
Succulent Karoo, South Africa.
Rhine River, Europe.
Coastal Japan.
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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
conservation
80
Life expectancy
Infant mortality
70
150
60
100
50
50
40
0
30
1900
Figure 55.23
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1950
Year
2000
Life expectancy (years)
Infant mortality (per 1,000 live births)
200
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
Figure 55.24a
(a) Detail of animals in a Paleolithic mural, Lascaux, France
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• But our behavior
– Reflects remnants of our ancestral attachment
to nature and the diversity of life, the concept
of biophilia
Figure 55.24b
(b) Biologist Carlos Rivera Gonzales examining a tiny tree frog in
Peru
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• Our innate sense of connection to nature
– May eventually motivate a realignment of our
environmental priorities
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