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Chapter 55 ~ Conservation Biology
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
Restoration ecology
applies ecological principles– In an effort to return degraded ecosystems to
conditions as similar as possible to their natural state
Tropical forests– Contain some of the greatest concentrations of
species– Are being destroyed at an alarming rate
Figure 55.1
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
The Three Levels of Biodiversity Biodiversity has three main
components– Genetic diversity
– Species diversity
– Ecosystem diversity
Genetic Diversity
Genetic diversity comprises– The genetic variation within a population– The genetic variation between populations
Species Diversity
Species diversity– Is the variety of species in an ecosystem or
throughout the biosphere
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
(a) Philippine eagle
(b) Chinese river dolphin
(c) Javan rhinocerosFigure 55.3a–c
Conservation biologists , such as E.O. Wilson, are concerned about species loss
the Hundred Heartbeat Club
– Species that number fewer than 100 individuals and are only that many heartbeats from extinction
Ecosystem Diversity
Ecosystem diversity– Identifies the variety of ecosystems in the
biosphere– Is being affected by human activity
Biodiversity and Human Welfare
Species diversity– Brings humans many practical benefits
Benefits of Species and Genetic Diversity
Many pharmaceuticals– Contain substances originally derived from
plants
Figure 55.4
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
Ecosystem Services
Our welfare is directly linked to biotic components of ecosystems– Nutrient cycling– Detoxification of waste waters– Purifying air– Preserve fertile sol– Need I go on!!
Four Major Threats to Biodiversity
– Habitat destruction—NUMERO UNO!– Introduced species– Overexploitation– Disruption of “interaction networks”
1. 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
Many natural landscapes have been broken up– Fragmenting habitat into small patches
Figure 55.5
In almost all cases– Habitat fragmentation and destruction leads to
loss of biodiversity
2. Introduced Species Introduced
species/invasive/exotic/nonnative– May be
Intentional Nonintentional
( you all should remember this—remember the Kudzu; Zebra mussels?)
Introduced species that gain a foothold in a new habitat– Usually disrupt their
adopted community– No natural predators– Outcompete native
organisms
(a) Brown tree snake, intro- duced to Guam in cargo
(b) Introduced kudzu thriving in South CarolinaFigure 55.6a, b
3. 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
The fishing industry
Tuna at risk!! Swordfish too! Salmon!!
This impacts other as well—Dolphins caught in tuna nets!
Figure 55.7
4. Disruption of Interaction Networks
The extermination of keystone species by humans– Can lead to major changes
in the structure of communities
– Keystone species Not necessarily abundant But,exerts string control on
community structure due to its ecological niche
More info at http://www.bagheera.com/
inthewild/spot_spkey.htm
Figure 55.8
Elephants Sea otters
Biologists focusing on conservation at the population and species levels– Follow two main approaches
Small-Population Approach
Conservation biologists who adopt the small-population approach– Study the processes that can cause very small
populations finally to become extinct
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
The key factor driving the extinction vortex
– Is the loss of the genetic variation necessary to enable evolutionary responses to environmental change
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
As a test of the extinction vortex hypothesis– Scientists imported genetic variation by
transplanting birds from larger populations
The declining population rebounded– Confirming that it had been on its way down an
extinction vortexEXPRIMENT 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
ber
of m
ale
bird
s
(a) Population dynamics
(b) Hatching rate
200
150
100
50
0
1970 1975 1980 1985 1990 1995 2000
Year
Egg
s ha
tche
d (%
)
100
90
80
70
60
50
40
301970-74 1975-79 1980-84 1985-89 1990 1993-97
Years
Figure 55.10
Case Study: Analysis of Grizzly Bear Populations
population viability analyses– Was conducted as part of a long-term study of
grizzly bears in Yellowstone National Park
Figure 55.11
This study has shown that the grizzly bear population– Has grown substantially in the past 20 years
Num
ber
of
ind
ivid
uals
150
100
50
01973 1982 1991 2000
Females with cubs
Cubs
YearFigure 55.12
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
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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
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
Fragmentation and Edges The boundaries, or edges, between ecosystems– As habitat fragmentation increases– And edges become more extensive, biodiversity
tends to decrease
(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
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
Corridors:Connect Habitat Fragments
A movement corridor– Is a narrow strip of quality habitat connecting
otherwise isolated patches
In areas of heavy human useArtificial corridors are sometimes
constructed
Figure 55.16
15th panther killed on Florida roadways this year, breaking previous records
September 2007 (www.wildlifeextra.com )
Establishing Protected Areas
Conservation biologists are applying their understanding of ecological dynamics– In establishing protected areas to slow the loss
of biodiversity
Much of the focus on establishing protected areas– Has been on hot spots of biological diversity
Biological Hot Spots 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
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
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
Zoned Reserves
The zoned reserve model recognizes that conservation efforts– Often involve working in landscapes that are
largely human dominated
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
Some zoned reserves in the Fiji islands are closed to fishing– Which actually helps to improve fishing success
in nearby areas
Figure 55.20
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
Whether a disturbance is natural or caused by humans
– Seems to make little difference in this size-time relationship
Rec
over
y tim
e (y
ears
)(lo
g sc
ale)
104
1,000
100
10
1
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
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
Bioremediation
Bioremediation– Is the use of living organisms to detoxify
ecosystems
Biological Augmentation
Biological augmentation– Uses organisms to add essential materials to a
degraded ecosystem
Exploring Restoration
The newness and complexity of restoration ecology– Require scientists to consider alternative
solutions and adjust approaches based on experience
Exploring restoration worldwide
Truckee River, Nevada. Kissimmee River, Florida.
Equator
Figure 55.22
Tropical dry forest, Costa Rica. Succulent Karoo, South Africa.
Rhine River, Europe. Coastal Japan.Figure 55.22
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?
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
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
Human living conditions in Costa Rica– Have improved along with ecological
conservation
Infa
nt
mo
rta
lity
(pe
r 1
,00
0 li
ve b
irth
s)
200
150
100
50
01900 1950 2000
80
70
60
50
40
30
Year
Life expectancyInfant mortality
Life
exp
ect
an
cy (
yea
rs)
Figure 55.23
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
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
Our innate sense of connection to nature– May eventually motivate a realignment of our
environmental priorities