Transcript CO 2

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 38
Conservation Biology
Modules 38.1 – 38.3
From PowerPoint® Lectures for Biology: Concepts & Connections
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Saving the Key Deer
• Modern human culture and the rapidly growing
global human population have created a
biodiversity crisis
– There is a rapid decrease in
the variety of species on Earth
• The decline in Key deer
populations is an example of
this crisis
– The Key deer is a miniature
subspecies of the whitetail
deer found only in the Florida
Keys
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• The Key deer was nearly exterminated by
hunting in the early 1900s
• The National Key Deer Pine Refuge was
established on Big Pine Key island in 1957
– The deer population rebounded to 600-800
• The Key deer is still on the endangered species
list
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• The human population on Big Pine Key has
increased tenfold since 1967
– Development has reduced the Key deer
habitat
– Motorists have
become the
main threat
to the deer's
survival
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• Conservation biology is a goal-oriented science
that seeks to counter the biodiversity crisis
• Conservation biology relies on research from
all levels of ecology, from populations to
ecosystems
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THE BIODIVERSITY CRISIS: AN OVERVIEW
38.1 Habitat destruction, introduced species, and
overexploitation are the major threats to
biodiversity
• Human alteration of
habitats poses the
single greatest threat
to biodiversity
– The loss of tropical
rain forests and
marine habitats are
especially
devastating
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Figure 38.1A
• Competition with introduced species also
threatens many species in their native habitats
– Introduced species are those that have been
transferred to an area where they did not
occur naturally
– Examples: European starlings, pigeons, and
house sparrows
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• One of the largest rapid-extinction events ever
recorded occurred in Lake Victoria, East Africa
– 200 species of freshwater fish were lost due to
the introduction of the Nile perch
Figure 38.1B
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• Overexploitation of wildlife also threatens many
species
– Excessive commercial harvest or sport hunting
has reduced the numbers of many species
– Examples: whales, American bison, Galápagos
tortoises, and numerous fish
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38.2 Biodiversity is vital to human welfare
• Preservation of biodiversity is important to
humans for aesthetic, ethical and practical
reasons
• Biodiversity provides humans with food,
clothing, shelter, oxygen, soil fertility, etc.
• We evolved in Earth's ecosystem
– Large-scale changes in the ecosystem threaten
us as well as other species
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• Medicinal plants and
their derivatives play
an important role in
the pharmaceutical
industry
– The rosy periwinkle
of Madagascar
provides two
substances effective
in the treatment of
Hodgkin’s disease
Figure 38.2
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38.3 Connection: Technology and the population
explosion compound our impact on habitats
and other species
• The explosive growth of the human population
and of technology continues today
• Although the populations of developing
nations are growing the fastest, it is the
resource consumption of the less populous,
developed nations that puts a greater strain on
the biosphere
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Table 38.3
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• Oil spills, acid rain,
ozone depletion, and
chemical pesticides
affect the entire world
Figure 38.3a
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• Chemical
pesticides are
concentrated in
food chains by
biological
magnification
DDT concentration:
increase of
10 million times
DDT in
fish-eating birds
25 ppm
DDT in
large fish
2 ppm
DDT in
small fish
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm
Figure 38.3B
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38.4 Connection: Rapid global warming could alter
the entire biosphere
• Burning of fossil fuels is increasing the amount
of CO2 and other greenhouse gases in the air
Figure 38.4A
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Light
CO2
Heat
CO2
CO2
Figure 38.4B
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• Projected atmospheric temperatures indicate an
increase in greenhouse gases
Figure 38.4C
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• An increase in global temperature could have
many negative effects
– Change in climate patterns
– Melting of polar ice
– Flooding of coastal regions
– Increase in the rate of species loss
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THE GEOGRAPHIC DISTRIBUTION OF
BIODIVERSITY
38.5 Some locations in the biosphere are especially
rich in biodiversity
• Environments are patchy
– As a result, species are not evenly distributed
• Geographic distribution patterns for many
species indicate an uneven density
– Example: terrestrial birds in North and Central
America
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• Density of bird
species
Figure 38.5A
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• Biodiversity hot spots are relatively small areas
with a large concentration of species
• Many species in these hot spots are endemic
– They are found nowhere else
• Biodiversity hot spots can also be hot spots of
extinction
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• Location of some biodiversity hot spots
Figure 38.5B
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• Endemic species are highly sensitive to habitat
degradation and thus prone to extinction
• Many migratory species, both terrestrial and
aquatic, require international protection
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• Monarch butterflies
migrate throughout
Canada and the United
States during the
summer months
– In the autumn months,
they migrate to local
sites in Mexico and
California
– Such overwintering
populations are
susceptible to habitat
disturbances
Figure 38.5C
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• Sea turtles, such as the loggerhead turtle, are
threatened in their ocean feeding grounds and
on land
Figure 38.5D
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CONSERVATION OF POPULATIONS AND
SPECIES
38.6 There are two approaches to studying
endangered populations
• Habitat degradation can lead to population
fragmentation
– Portions of populations
are split and
subsequently isolated
– It often results in species
being designated as
threatened or endangered
Figure 38.6A
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• The Endangered Species Act (ESA) defines an
endangered species as one that is in danger of
extinction throughout all or a significant
portion of its range
– Example: the northern
spotted owl
• The ESA defines a
threatened species as one
that is likely to become
endangered in the
foreseeable future
Figure 38.6B
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• Some conservation biologists believe that the
smallness of a population will ultimately drive it
to extinction
• The small-population approach
– Identifies the minimum viable population size
for a threatened species
– Focuses on preserving genetic variation
• The declining-population approach diagnoses
and treats the causes of a population's decline
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38.7 Identifying critical habitat factors is a central
goal in conservation research
• Identifying the specific
combination of habitat
factors that is critical for
a species is pivotal in
conservation biology
• The red-cockaded
woodpecker requires
three habitat factors
– A mature pine forest
Figure 38.7A
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– Low growth of
plants among
the mature
pine trees
– Controlled
fires to reduce
forest
undergrowth
Figure 38.7B, C
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38.8 Connection: Increased fragmentation
threatens many populations: A case study
• Increased fragmentation threatens many
species
– This includes those whose populations were
historically highly fragmented
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• One example is the endangered bull trout
– It inhabits lakes, rivers, and mountain streams
in northwestern Canada and the United States
Figure 38.8A
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• The bull trout requires cold, fast-flowing
streams with pebble-covered bottoms and little
or no silt
Figure 38.8B
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• Before human
intervention, the bull
trout population
consisted of four
subpopulations
S1
S3
S2
S4
Egg-laying sites in mountain streams
Regular, frequent dispersal and gene flow
between subpopulations
Irregular, infrequent dispersal; minimal gene
flow between subpopulations
Figure 38.8C, left
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• The bull trout
population has been
further fragmented
and reduced by
– the construction of
hydroelectric dams
– logging
– road building
– mining
s1
s2
Mill site
for silver
mine
s3
s5
s4
Hydroelectric
dam
Hydroelectric
dam
Egg-laying sites in mountain streams
Clear-cut (logged) areas
Roads
Irregular, infrequent dispersal; minimal gene
flow between subpopulations
Figure 38.8C, right
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• Conservation biologists often use computer
simulations in a population viability analysis
(PVA)
– PVA incorporates as much information about a
population's current status as available
– It predicts a species' chance for long-term
survival
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MANAGING AND SUSTAINING ECOSYSTEMS
38.9 Sustaining ecosystems and landscapes is a
conservation priority
• Conservation efforts are increasingly aimed at
learning how to sustain whole ecosystems and
landscapes
• Landscape ecology employs ecological
principles to study land-use patterns
– It aims to make species conservation a functional
part of those patterns
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• Researchers often use gap analysis to study the
distribution of organisms relative to landscape
features and habitat types
• Gap analysis employs computerized maps along
with information on the distribution of
organisms
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Map of
vegetation
patterns and
river course
Distribution
of rare,
endemic
species
Distribution
of protected
areas
Final
overlay map
Figure 38.9A
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• Gap analysis can highlight areas with the
greatest concentrations of rare and endangered
species outside of protected areas
– It can lead to
sustaining
the
biodiversity
of the whole
area
Figure 38.9B
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38.10 Edges and corridors can strongly influence
landscape biodiversity
• Boundaries between ecosystems have their own
set of features and assemblages of species
• Human activities
can create edges
that are more
abrupt than
those found
naturally
Figure 38.10A
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• The increased frequency and abruptness of
edges can increase the loss of species
– Populations of the
brown-headed cowbird,
an edge-adapted species,
are currently expanding
– Populations of songbird
species are declining
Figure 38.10B
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• Movement corridors are strips or clumps of
quality habitat that connect otherwise isolated
habitat patches
– They may be helpful or harmful to fragmented
populations
• Corridors can
promote dispersal
and reduce
inbreeding in
declining
populations
Figure 38.10C
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38.11 Restoring degraded habitats is a developing
science
• Restoration ecology uses ecological principles
to develop ways to return degraded ecosystems
to conditions as similar as possible to their
natural, predegraded state
• There are two strategies in restoration ecology
– Bioremediation
– Augmentation
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• Bioremediation is the
use of living organisms
to detoxify polluted
ecosystems
– These organisms are
usually prokaryotes,
fungi, or plants
– These lichens are
concentrating mining
wastes
Figure 38.11A
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• Augmentation of ecosystem processes involves
resupplying an area with key factors that have
been removed
• Encouraging the growth of
plants that thrive on
nutrient-poor soils can
hasten the rate of recovery
of some tropical areas
– In Puerto Rico, the legume
Albizia helped set the stage
for recolonization by native
species
Figure 38.11B
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38.12 Sustainable development is an ultimate goal
• In numbers, geographic range, and capacity to
alter the biosphere, our species is clearly one
of the most successful ones ever to inhabit
planet Earth
• Human attitudes and environmental
awareness are of utmost importance in the
search for solutions to the biodiversity crisis
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• The gray-headed flying fox symbolizes the
biodiversity crisis
• Habitat destruction and the
killing of animals as pests
has reduced the population
75% in the past 25 years
• Further decrease could
endanger this species and
hurt its ecological role in
maintaining forest
diversity by pollination and
seed dispersal
Figure 38.12
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• Understanding the biosphere's limits and
vulnerability and our own linkages to the
natural world may help us make decisions that
lead to a sustainable future
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