Biology
Sylvia S. Mader
Michael Windelspecht
Chapter 47
Conservation of
Biodiversity
Lecture Outline
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Outline
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47.1 Conservation Biology and Biodiversity
47.2 Value of Biodiversity
47.3 Causes of Extinction
47.4 Conservation Techniques
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47.1 Conservation Biology and
Biodiversity
• Considers all aspects of biodiversity
– General goal is conserving natural resources
for this and future generations
– Primary goal is the management of
biodiversity
• The variety of life on Earth
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Conservation Biology and
Biodiversity
• For conservation biology to be effective,
scientists must evaluate larger connections
within the biosphere
– High level of biodiversity is desirable
– Causes of present-day extinction, how to prevent
future extinctions from occurring, and consequences
of reduced biodiversity
– Bioinformatics is utilized to protect biodiversity
• Collecting of, analyzing, and making readily available
biological information, using modern computer technology
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Conservation Biology and
Biodiversity
• Biodiversity
– At its simplest level, biodiversity refers to the
variety of species on Earth
• Estimated that between 10 and 50 million species
currently exist
• Endangered Species
– One that is in peril of immediate extinction throughout all
or most of its range
• Threatened Species
– Organisms that are likely to become endangered in the
near future
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Conservation Biology and
Biodiversity
• Biodiversity
– Ecologists describe biodiversity as a
combination of three levels of biological
organization:
• Genetic diversity
• Community diversity
• Landscape diversity
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Conservation Biology and
Biodiversity
• Biodiversity
– Genetic diversity refers to variations among
the members of a population
• Populations with high genetic diversity are more
likely to have some individuals that can survive a
change in the structure of their ecosystem
• If a species’ population is small and isolated, it is
more likely to become extinct due to a limited
genetic diversity.
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Conservation Biology and
Biodiversity
• Biodiversity
– Ecosystem diversity is dependent on
interactions of species in a particular area
• A diverse community composition will increase the
levels of biodiversity in the biosphere
• An effective approach to conservation is to
conserve species that play a key role within the
ecosystem
– Saving an entire community can save many species
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Conservation Biology and
Biodiversity
• Biodiversity
– Landscape diversity involves a group of
interacting ecosystems within one landscape
• Landscape – Ex: mountains, rivers, grasslands
• Fragmentation of the landscape reduces
reproductive capacity and food availability
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Number of Described Species
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plants 240,000
fungi 63,665
insects 900,000
animals 280,000
bacteria and
archaea 5,000
protists 55,000
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Conservation Biology and
Biodiversity
• Distribution of Biodiversity
– Biodiversity is not evenly distributed
throughout the biosphere
– Biodiversity is highest at the tropics
– Biodiversity hotspots
• Contain about 44% of known higher plant species
and 35% of terrestrial vertebrate species
• Represent only about 1.4% of earth’s land area
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47.2 Value of Biodiversity
• Direct Value
– A great number of species perform services
from which humans can derive an economic
value.
• These include:
– Medicinal value
– Agricultural value
– Consumptive Use Value
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Value of Biodiversity
• Direct Value (continued)
– Medicinal Value
• Most of the prescription drugs currently used in the
United States were originally derived from living
organisms
– Worth about $200 billion
• Ex: Rosy Periwinkle
– Chemicals from this plant are currently used to treat
leukemia and Hodgkin disease
– These drugs have significantly increased survival rates
for children
• Other examples include the use of penicillin in the
treatment of bacterial infections; the use of blood from
Limulus used to ensure that medical devices remain
free of bacteria
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Value of Biodiversity
• Direct Value (continued)
– Agricultural Value
• Wheat, corn, and rice are derived from wild plants
that were modified to increase their yield
• Natural predators of plant pests have been
introduced to agricultural systems to reduce the
impact of the pest on plant yields
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Value of Biodiversity
• Direct Value (continued)
– Consumptive Use Value
• Humans have had success cultivating crops,
domesticating animals, growing trees in
plantations, etc.
– However, most freshwater and marine harvests must be
hunted, rather than grown via aquaculture, for human
consumption
• Additional products associated with the
environment are sold commercially
– Wild fruits, vegetables, skins, fibers, beeswax and
seaweed
– Profits from the sale of these products provide an
economic benefit to the human population
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Value of Biodiversity
• Indirect Value
– Based on the services ecosystems provide
simply by their own existence.
– These include:
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Biogeochemical cycles
Waste recycling
Provision of Fresh Water
Prevention of Soil Erosion
Regulation of Climate
Ecotourism
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Value of Biodiversity
• Indirect Value (continued)
– Biogeochemical Cycles
• The biodiversity within ecosystems contributes to
the workings of the water, carbon, nitrogen,
phosphorous, and other biogeochemical cycles
• Humans are dependent upon these cycles for
fresh water, removal of carbon dioxide from the
atmosphere, uptake of excess soil nitrogen, and
provision of phosphate
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Value of Biodiversity
• Indirect Value (continued)
– Waste Recycling
• Decomposers break down dead organic matter
and other types of wastes into inorganic nutrients
used by producers within ecosystems.
• This function aids humans
– The human population dumps millions of tons of waste
material into natural ecosystems each year
– If it were not for decomposition this waste would soon
cover the entire surface of the Earth
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Value of Biodiversity
• Indirect Value (continued)
– Provision of Fresh Water
• The water cycle provides fresh water to terrestrial
ecosystems
• Humans use this fresh water in innumerable ways
• Freshwater ecosystems provide us with a large
diversity of species we can use as a source of food
• Forests and some other natural ecosystems soak
up water and release it at a regular rate, thereby
reducing flooding
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Value of Biodiversity
• Indirect Value (continued)
– Prevention of Soil Erosion
• Intact ecosystems naturally retain soil and prevent
soil erosion
• The importance of this attribute is particularly
observed after deforestation
– Results in silt buildup
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Value of Biodiversity
• Indirect Value (continued)
– Regulation of Climate
• Trees provide shade and reduce the need for fans
and air conditioners in the summer
• Globally, forests restore the climate by
incorporating carbon dioxide from the atmosphere
• Reduction of forests reduces the carbon dioxide
uptake and oxygen output through photosynthesis
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Value of Biodiversity
• Indirect Value (continued)
– Ecotourism
• In the United States, nearly $4 billion is spent on
fees, travel, lodging, and food within natural
settings
• Many underdeveloped countries in tropical regions
take advantage of this by offering “ecotours” of the
local biodiversity
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Value of Biodiversity
• Biodiversity and Natural Ecosystems
– Large-scale changes in biodiversity have
significant impacts on ecosystems:
• Ecosystem performance improves with increasing
biodiversity
• Rate of photosynthesis increases as biodiversity
increases
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Influence of Biodiversity on Community
Productivity
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Rate of Photosynthesis
3.0
2.5
2.0
1.5
1.0
1 2
4
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Number of Plant Species
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47.3 Causes of Extinction
• Known causes of species extinction are
due to:
– Habitat loss (85%)
– Exotic species (50%)
– Pollution (24%)
– Overexploitation (17%)
– Disease (3%)
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Causes of Extinction
• Habitat Loss
– Occurs in all ecosystems
– Recent concern focuses on tropical rain
forests and coral reefs because they are rich
in species
– Loss of habitat affects terrestrial, freshwater,
and marine biodiversity
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Habitat Loss
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Roads cut through forest
Habitat Loss
Exotic Species
Pollution
Overexploitation
Forest occurs in patches
Disease
0 20
a. Threats to
wildlife
40 60 80 100
% Species
Affected by Threat
b. Macaws
Destroyed areas
c. Wildlife habitat is reduced.
b: © IT Stock/PunchStock RF; c (top): Courtesy Woods Hole Research Center; c (center): Courtesy R.O. Bierregaard;
c (bottom): Courtesy Thomas Stone, Woods Hole Research Center
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Causes of Extinction
• Exotic Species
– Nonnative species that migrate, or are
introduced, into a new ecosystem
– Humans introduce exotic species into
ecosystems through:
• Colonization
• Horticulture and Agriculture
• Accidental Transport
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Exotic Species
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a.
b.
a: © Chuck Pratt/Bruce Coleman, Inc.; b: © Chris Johns/National Geographic Image Collection
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Causes of Extinction
• Impact of Exotics on Islands
– Islands are particularly susceptible to
environmental discord due to the introduction
of exotic species
• Island inhabitants have native species closely
adapted to one another and do not compete well
with exotic species
– Ex:
» Myrtle tree introduced to the Hawaiian Islands
» Brown tree snake introduced to Pacific islands
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Causes of Extinction
• Pollution
– Any environmental change that adversely
affects living things
– Third main cause of extinction
– Biodiversity is particularly threatened by
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Acid deposition
Eutrophication
Ozone depletion
Synthetic organic chemicals
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Causes of Extinction
• Pollution (continued)
– Acid Deposition
• Sulfur dioxides and nitrogen oxides in automobile
gas react with water in the atmosphere to form
acids that are returned to Earth as either wet or dry
deposition
– Weakens trees and increases their susceptibility to
disease
– Kills small decomposers and invertebrates, thereby
disrupting entire ecosystems
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Causes of Extinction
• Pollution (continued)
– Eutrophication
• Excess nutrient runoff from terrestrial
environments result in algal growth in lakes
• As these algae die, the decomposers in the lake
break them down and reduce the amount of
oxygen in the lake.
– Results in death of fish and other aquatic organisms
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Causes of Extinction
• Pollution (continued)
– Ozone Depletion
• Ozone (O3) protects the surface of the Earth from
harmful UV rays
– Chlorofluorocarbons released from products such freon
used in older refrigerators destroy ozone
» Leads to impaired crop and tree growth, death of
plankton, and impairment of immune system function
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Causes of Extinction
• Pollution (continued)
– Organic Chemicals
• Organic chemicals such as nonylphenols used in a
variety of human products mimic the effect of
hormones
– Harms wildlife
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Causes of Extinction
• Climate Change
– Refers to recent changes in the Earth’s
climate
– Increased temperature of the Earth results in
drastic climatic changes
• Temperature increase is caused, in part, by
increased concentrations of greenhouse gases,
such as CO2 that serve to trap heat within the
atmosphere
– Results in ecosystem disruption and extinction
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Climate Change
Mean Global Temperature Change (°C)
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5.5
4.5
3.5
maximum likely increase
most probable temperature
increase for 2 × CO2
2.5
1.5
minimum likely increase
0.5
–0.5
1860
1940
2020 2060 2100
Year
a.
b.
b: Courtesy Walter C. Jaap/Florida Fish & Wildlife Conservation Commission
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Causes of Extinction
• Overexploitation
– The number of individuals taken from the population
is so great that the population becomes severely
reduced in numbers
– Positive feedback cycle
• The smaller the population, the more valuable its members,
and the greater the incentive to capture the few remaining
organisms
– The market forces driving overexploitation:
• Exotic Pets
• Poaching
• Overfishing
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Overexploitation of Asian Turtles
• Collection and trade of terrestrial and freshwater turtles for human
consumption has surged in Asia
– 40% - 60% of all species are currently endangered
• Due to their life history characteristics (slow growth, low reproductive
rates), wild populations are not likely to recover after they have been
plundered.
• Major Challenges Today and in the Future include:
– Lack of knowledge of range, natural history, and conservation needs of
turtle species
– Need for legislation of diverse countries to be passed that ensures the
long-term survival of turtle populations
– Threat of invasive species and spread of disease from aquaculture
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47.4 Conservation Techniques
• Habitat preservation and restoration are
important in preserving biodiversity
– Habitat Preservation
• Biodiversity hotspots, small areas with large numbers of
endemic species not found anyplace else, are important
targets for conservation
• Keystone Species
– Species that influence the viability of a community
– Extinction of these species can lead to additional extinctions
and loss of biodiversity
• Flagstone Species
– Charismatic species that evoke a strong emotional response in
humans
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Conservation Techniques
• Habitat Preservation (continued)
– Metapopulation
• Small population isolated because of habitat
fragmentation
– Source Population
» One that most likely lives in a favorable area and its
birth rate is most likely higher than its death rate
– Sink Population
» Organisms that have moved from a source
population to an environment not as favorable and
where the birth and death rates are approximately
equal
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Conservation Techniques
• Landscape Preservation
– Landscape protection for one species benefits
other wildlife in the same space
• The Edge Effect
– The edge around a patch of habitat has
conditions different from the patch interior
– An edge reduces the amount of habitat typical
for an ecosystem
• Can result in a significant reduction in population
size
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Edge Effect
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30.55%
increasing percentage of
patch influenced by edge effects
43.75%
64%
habitat patch
a.
brown-headed
cowbird chick
88.8%
yellow warbler
chick
area subject
to edge effect
b.
b: © Jeff Foott Productions
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Conservation Techniques
• Habitat Restoration
– Restoration ecology seeks scientific ways to
return ecosystems to their state prior
• Three Principles of restoration ecology:
– Begin as soon as possible before remaining
fragments are lost
– Once natural history is understood, use
biological techniques to mimic natural
processes
– Goal is sustainable development
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