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Transcript of Globally, 12% of birds, 21% of mammals, and 32% of amphibians are threatened with extinction More...
![Page 1: Globally, 12% of birds, 21% of mammals, and 32% of amphibians are threatened with extinction More than 50% of wetlands in the contiguous United States.](https://reader034.fdocuments.us/reader034/viewer/2022051621/5697bf6f1a28abf838c7d1e1/html5/thumbnails/1.jpg)
Globally, 12% of birds, 21% of mammals, and 32% of amphibians are threatened with extinction
More than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems
![Page 2: Globally, 12% of birds, 21% of mammals, and 32% of amphibians are threatened with extinction More than 50% of wetlands in the contiguous United States.](https://reader034.fdocuments.us/reader034/viewer/2022051621/5697bf6f1a28abf838c7d1e1/html5/thumbnails/2.jpg)
In the United States, 25% of prescriptions contain substances originally derived from plants
For example, the North Atlantic bluefin tuna population decreased by 80% in ten years
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LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures byErin Barley
Kathleen Fitzpatrick
Conservation Biology and Global Change
Chapter 56
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Overview: Striking Gold
• Scientists have named and described 1.8 million species
• Biologists estimate 10–100 million species exist on Earth
• Tropical forests contain some of the greatest concentrations of species and are being destroyed at an alarming rate
• Humans are rapidly pushing many species toward extinction
© 2011 Pearson Education, Inc.
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Figure 56.1
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Figure 56.2
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• Conservation biology, which seeks to preserve life, integrates several fields
– Ecology
– Physiology
– Molecular biology
– Genetics
– Evolutionary biology
© 2011 Pearson Education, Inc.
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Concept 56.1: Human activities threaten Earth’s biodiversity
• Rates of species extinction are difficult to determine under natural conditions
• The high rate of species extinction is largely a result of ecosystem degradation by humans
• Humans are threatening Earth’s biodiversity
© 2011 Pearson Education, Inc.
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Three Levels of Biodiversity
• Biodiversity has three main components– Genetic diversity
– Species diversity
– Ecosystem diversity
© 2011 Pearson Education, Inc.
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Figure 56.3
Genetic diversityin a vole population
Species diversityin a coastalredwood ecosystem
Community andecosystem diversityacross thelandscape ofan entire region
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Genetic Diversity
• Genetic diversity comprises genetic variation within a population and between populations
© 2011 Pearson Education, Inc.
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Species Diversity
• Species diversity is the variety of species in an ecosystem or throughout the biosphere
• According to the U.S. Endangered Species Act– An endangered species is “in danger of
becoming extinct throughout all or a significant portion of its range”
– A threatened species is likely to become endangered in the foreseeable future
© 2011 Pearson Education, Inc.
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Figure 56.4Philippine eagle
Javanrhinoceros
Yangtze Riverdolphin
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Figure 56.4a
Philippine eagle
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Figure 56.4b
Yangtze River dolphin
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Figure 56.4c
Javan rhinoceros
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Ecosystem Diversity
• Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere
• More than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems
© 2011 Pearson Education, Inc.
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• The local extinction of one species can have a negative impact on other species in an ecosystem
– For example, flying foxes (bats) are important pollinators and seed dispersers in the Pacific Islands
© 2011 Pearson Education, Inc.
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Figure 56.5
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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 practical benefits
© 2011 Pearson Education, Inc.
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Benefits of Species and Genetic Diversity
• Species related to agricultural crops can have important genetic qualities
– For example, plant breeders bred virus-resistant commercial rice by crossing it with a wild population
• In the United States, 25% of prescriptions contain substances originally derived from plants
– For example, the rosy periwinkle contains alkaloids that inhibit cancer growth
© 2011 Pearson Education, Inc.
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Figure 56.6
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• The loss of species also means loss of genes and genetic diversity
• The enormous genetic diversity of organisms has potential for great human benefit
© 2011 Pearson Education, Inc.
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Ecosystem Services
• Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life
• Some examples of ecosystem services– Purification of air and water
– Detoxification and decomposition of wastes
– Cycling of nutrients
– Moderation of weather extremes
© 2011 Pearson Education, Inc.
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Threats to Biodiversity
• Most species loss can be traced to four major threats
– Habitat destruction
– Introduced species
– Overharvesting
– Global change
© 2011 Pearson Education, Inc.
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Habitat Loss
• Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere
• In almost all cases, habitat fragmentation and destruction lead to loss of biodiversity
• For example – In Wisconsin, prairie occupies <0.1% of its
original area
– About 93% of coral reefs have been damaged by human activities
© 2011 Pearson Education, Inc.
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Figure 56.7
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Introduced Species
• Introduced species are those that humans move from native locations to new geographic regions
• Without their native predators, parasites, and pathogens, introduced species may spread rapidly
• Introduced species that gain a foothold in a new habitat usually disrupt their adopted community
© 2011 Pearson Education, Inc.
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• Sometimes humans introduce species by accident– For example, the brown tree snake arrived in
Guam as a cargo ship “stowaway” and led to extinction of some local species
© 2011 Pearson Education, Inc.
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Figure 56.8
(a) Brown tree snake
(b) Kudzu
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Figure 56.8a
(a) Brown tree snake
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• Humans have deliberately introduced some species with good intentions but disastrous effects– For example, kudzu was intentionally introduced
to the southern United States
© 2011 Pearson Education, Inc.
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Figure 56.8b
(b) Kudzu
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Overharvesting
• Overharvesting is human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound
• Large organisms with low reproductive rates are especially vulnerable to overharvesting– For example, elephant populations declined
because of harvesting for ivory
© 2011 Pearson Education, Inc.
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• DNA analysis can help conservation biologists identify the source of illegally obtained animal products
– For example, DNA from illegally harvested ivory can be used to trace the original population of elephants to within a few hundred kilometers
© 2011 Pearson Education, Inc.
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Figure 56.9
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• Overfishing has decimated wild fish populations– For example, the North Atlantic bluefin tuna
population decreased by 80% in ten years
© 2011 Pearson Education, Inc.
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Figure 56.10
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Global Change
• Global change includes alterations in climate, atmospheric chemistry, and broad ecological systems
• Acid precipitation contains sulfuric acid and nitric acid from the burning of wood and fossil fuels
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• Air pollution from one region can result in acid precipitation downwind
– For example, industrial pollution in the midwestern United States caused acid rain in eastern Canada in the 1960s
• Acid precipitation kills fish and other lake-dwelling organisms
• Environmental regulations have helped to decrease acid precipitation
– For example, sulfur dioxide emissions in the United States decreased 31% between 1993 and 2002
© 2011 Pearson Education, Inc.
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Year
pH
1960 ‘65 ‘75 ‘80‘70 ‘85 ‘90 ‘95 2000 ‘05 ‘10
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4.0
Figure 56.11
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Concept 56.2: 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
– The small-population approach
– The declining-population approach
© 2011 Pearson Education, Inc.
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Small-Population Approach
• The small-population approach studies processes that can make small populations become extinct
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The Extinction Vortex: Evolutionary Implications of Small Population Size
• A small population is prone to inbreeding and genetic drift, which draw it down an extinction vortex
• The key factor driving the extinction vortex is loss of the genetic variation necessary to enable evolutionary responses to environmental change
• Small populations and low genetic diversity do not always lead to extinction
© 2011 Pearson Education, Inc.
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Smallpopulation
GeneticdriftInbreeding
Lowerreproduction
Reduction inindividual
fitness andpopulationadaptability
Highermortality
Loss of genetic
variability
Smallerpopulation
Figure 56.12
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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
• To test the extinction vortex hypothesis, scientists imported genetic variation by transplanting birds from larger populations
• The declining population rebounded, confirming that low genetic variation had been causing an extinction vortex
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Figure 56.13
(a) Population dynamics
(b) Hatching rate
Translocation
Year
Year
1970 19951975 1980 1985 1990
1970–‘74 ‘90‘75–‘79 ‘80–‘84 ‘85–‘89 ‘93–‘97
RESULTS
200
150
100
90
80
70
60
50
40
30
50
0
100
Nu
mb
er o
f m
ale
bir
ds
Eg
gs
hat
ched
(%
)
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Figure 56.13a
Translocation
Year1970 19951975 1980 1985 1990
RESULTS
200
150
50
0
(a) Population dynamics
100
Nu
mb
er
of
ma
le b
ird
s
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Figure 56.13b
(b) Hatching rateYear
1970–‘74 ‘90‘75–‘79 ‘80–‘84 ‘85–‘89 ‘93–‘97
100
90
80
70
60
50
40
30
Eg
gs
hat
ched
(%
)RESULTS
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Figure 56.13c
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Minimum Viable Population Size
• Minimum viable population (MVP) is the minimum population size at which a species can survive
• The MVP depends on factors that affect a population’s chances for survival over a particular time
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Effective Population Size
• A meaningful estimate of MVP requires determining the effective population size, which is based on the population’s breeding potential
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• Effective population size (Ne) is estimated by
– where Nf and Nm are the number of females and the number of males, respectively, that breed successfully
• Viability analysis is used to predict a population’s chances for survival over a particular time interval
4NfNm
Nf + Nm
Ne =
© 2011 Pearson Education, Inc.
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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
• It is estimated that a population of 100 bears would have a 95% chance of surviving about 200 years
• This grizzly population is about 400, but the Ne is about 100
• How could you increase the viability of a small, isolated population of animals?
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Figure 56.14
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• The Yellowstone grizzly population has low genetic variability compared with other grizzly populations
• Introducing individuals from other populations would increase the numbers and genetic variation
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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
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Steps for Analysis and Intervention
• The declining-population approach involves several steps1. Confirm that the population is in decline
2. Study the species’ natural history
3. Develop hypotheses for all possible causes of decline
4. Test the hypotheses in order of likeliness
5. Apply the results of the diagnosis to manage for recovery
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Case Study: Decline of the Red-Cockaded Woodpecker
• Red-cockaded woodpeckers require living trees in mature pine forests
• These woodpeckers require forests with little undergrowth
• Logging, agriculture, and fire suppression have reduced suitable habitat
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Figure 56.15
Red-cockaded woodpecker
(a) Forests with low undergrowth (b) Forests with high, dense undergrowth
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Figure 56.15a
(a) Forests with low undergrowth
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• They have a complex social structure where one breeding pair has up to four “helper” individuals
• Individuals often have a better chance of reproducing by helping and waiting for an available cavity, instead of excavating new cavities
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Figure 56.15b
(b) Forests with high, dense undergrowth
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Figure 56.15c
Red-cockaded woodpecker
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• In a study where breeding cavities were constructed, new breeding groups formed only in these sites
• Based on this experiment, a combination of habitat maintenance and excavation of breeding cavities enabled this endangered species to rebound
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Weighing Conflicting Demands
• Conserving species often requires resolving conflicts between habitat needs of endangered species and human demands
• For example, in the U.S. Pacific Northwest, habitat preservation for many species is at odds with timber and mining industries
• Managing habitat for one species might have positive or negative effects on other species
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Concept 56.3: Landscape and regional conservation help sustain biodiversity
• Conservation biology has attempted to sustain the biodiversity of entire communities, ecosystems, and landscapes
• Ecosystem management is part of landscape ecology, which seeks 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
• Some species take advantage of edge communities to access resources from both adjacent areas
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Figure 56.16
(a) Natural edges
(b) Edges created by human activity
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Figure 56.16a
(a) Natural edges
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Figure 56.16b
(b) Edges created by human activity
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• The Biological Dynamics of Forest Fragments Project in the Amazon examines the effects of fragmentation on biodiversity
• Landscapes dominated by fragmented habitats support fewer species due to a loss of species adapted to habitat interiors
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Figure 56.17
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Corridors That Connect Habitat Fragments
• A movement corridor is a narrow strip of quality habitat connecting otherwise isolated patches
• Movement corridors promote dispersal and help sustain populations
• In areas of heavy human use, artificial corridors are sometimes constructed
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Figure 56.18
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Establishing Protected Areas
• Conservation biologists apply understanding of ecological dynamics in establishing protected areas to slow the loss of biodiversity
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Preserving Biodiversity Hot Spots
• A biodiversity hot spot is a relatively small area with a great concentration of endemic species and many endangered and threatened species
• Biodiversity hot spots are good choices for nature reserves, but identifying them is not always easy
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• Designation of hot spots is often biased toward saving vertebrates and plants
• Hot spots can change with climate change
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Video: Coral Reef
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Figure 56.19
Terrestrial biodiversityhot spots
Marine biodiversityhot spots
Equator
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Philosophy of Nature Reserves
• Nature reserves are biodiversity islands in a sea of habitat degraded by human activity
• Nature reserves must consider disturbances as a functional component of all ecosystems
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• An important question is whether to create fewer large reserves or more numerous small reserves
• One argument for large reserves is that large, far-ranging animals with low-density populations require extensive habitats
• Smaller reserves may be more realistic and may slow the spread of disease throughout a population
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Kilometers
1000 50
WYOMING
MONTANA
MONTANA
IDAHO
IDA
HO
WY
OM
ING
neSho sho
R.
ows R.
Yelltone
Snake R.
Yellowstone National Park
Grand TetonNational Park Biotic boundary for
short-term survival;MVP is 50 individuals.
Biotic boundary forlong-term survival;MVP is 500 individuals.
Figure 56.20
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Zoned Reserves
• The zoned reserve model recognizes that conservation often involves working in landscapes that are largely human dominated
• A zoned reserve includes relatively undisturbed areas and the modified areas that surround them and that serve as buffer zones
• Zoned reserves are often established as “conservation areas”
• Costa Rica has become a world leader in establishing zoned reserves
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Nicaragua
CostaRica
CARIBBEAN SEA
PACIFIC OCEAN
National park landBuffer zone
Pan
ama
(a) Zoned reserves in Costa Rica
(b) Tourists in one of Costa Rica’s zoned reserves
Figure 56.21
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Nicaragua
CostaRica
CARIBBEAN SEA
PACIFIC OCEAN
National park landBuffer zone
Pana
ma
(a) Zoned reserves in Costa Rica
Figure 56.21a
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Figure 56.21b
(b) Tourists in one of Costa Rica’s zoned reserves
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• Some zoned reserves in the Fiji islands are closed to fishing, which actually improves fishing success in nearby areas
• The United States has adopted a similar zoned reserve system with the Florida Keys National Marine Sanctuary
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Figure 56.22
FLORIDAGULF OF MEXICO
Florida Keys NationalMarine Sanctuary
50 km
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Figure 56.22a
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Concept 56.4: Earth is changing rapidly as a result of human actions
• The locations of preserves today may be unsuitable for their species in the future
• Human-caused changes in the environment include
– Nutrient enrichment– Accumulation of toxins– Climate change– Ozone depletion
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Nutrient Enrichment
• In addition to transporting nutrients from one location to another, humans have added new materials, some of them toxins, to ecosystems
• Harvest of agricultural crops exports nutrients from the agricultural ecosystem
• Agriculture leads to the depletion of nutrients in the soil
• Fertilizers add nitrogen and other nutrients to the agricultural ecosystem
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Figure 56.23
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• Critical load is the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity
• Nutrients that exceed the critical load leach into groundwater or run off into aquatic ecosystems– Agricultural runoff and sewage lead to phytoplankton
blooms in the Atlantic Ocean• Decomposition of phytoplankton blooms causes “dead
zones” due to low oxygen levels
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Figure 56.24
Winter Summer
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Figure 56.24a
Winter
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Figure 56.24b
Summer
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Toxins in the Environment
• Humans release many toxic chemicals, including synthetics previously unknown to nature
• In some cases, harmful substances persist for long periods in an ecosystem
• One reason toxins are harmful is that they become more concentrated in successive trophic levels
• Biological magnification concentrates toxins at higher trophic levels, where biomass is lower
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• PCBs and many pesticides such as DDT are subject to biological magnification in ecosystems
• Herring gulls of the Great Lakes lay eggs with PCB levels 5,000 times greater than in phytoplankton
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Herringgull eggs124 ppm
Lake trout4.83 ppm
Smelt1.04 ppm
Phytoplankton0.025 ppm
Zooplankton0.123 ppm
Co
nce
ntr
atio
n o
f P
CB
s
Biological magnification
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• In the 1960s Rachel Carson brought attention to the biomagnification of DDT in birds in her book Silent Spring
• DDT was banned in the United States in 1971• Countries with malaria face a trade-off between
killing mosquitoes (malarial vectors) and protecting other species
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Figure 56.26
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Greenhouse Gases and Global Warming
• One pressing problem caused by human activities is the rising level of atmospheric CO2
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Rising Atmospheric CO2 Levels
• Due to burning of fossil fuels and other human activities, the concentration of atmospheric CO2 has been steadily increasing
• Most plants grow faster when CO2 concentrations increase
• C3 plants (for example, wheat and soybeans) are more limited by CO2 than C4 plants (for example, corn)
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Year
CO2
Temperature
CO
2 co
nce
ntr
atio
n (
pp
m)
Ave
rag
e g
lob
al t
emp
erat
ure
(°C
)
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
390
380
370
360
350
340
330
320
310
300
14.9
14.8
14.7
14.6
14.5
14.4
14.3
14.2
14.1
14.0
13.9
13.8
13.7
13.6
Figure 56.27
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Figure 56.28
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How Elevated CO2 Levels Affect Forest Ecology: The FACTS-I Experiment
• The FACTS-I experiment is testing how elevated CO2 influences tree growth, carbon concentration in soils, insect populations, soil moisture, and other factors
• The CO2-enriched plots produced more wood than the control plots, though less than expected
• The availability of nitrogen and other nutrients appears to limit tree growth and uptake of CO2
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The Greenhouse Effect and Climate
• CO2, water vapor, and other greenhouse gases reflect infrared radiation back toward Earth; this is the greenhouse effect
• This effect is important for keeping Earth’s surface at a habitable temperature
• Increasing concentration of atmospheric CO2 is linked to increasing global temperature
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• Climatologists can make inferences about past environments and their climates
– Pollen and fossil plant records reveal past vegetation
– CO2 levels are inferred from bubbles trapped in glacial ice
– Chemical isotope analysis is used to infer past temperature
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• Northern coniferous forests and tundra show the strongest effects of global warming– For example, in 2007 the extent of Arctic sea ice
was the smallest on record• A warming trend would also affect the
geographic distribution of precipitation
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• Many organisms may not be able to survive rapid climate change
• Some ecologists support assisted migration, the translocation of a species to a favorable habitat beyond its native range
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• Global warming can be slowed by reducing energy needs and converting to renewable sources of energy
• Stabilizing CO2 emissions will require an international effort
• Recent international negotiations have yet to reach a consensus on a global strategy to reduce greenhouse gas emissions
• Reduced deforestation would also decrease greenhouse gas emissions
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Depletion of Atmospheric Ozone
• Life on Earth is protected from damaging effects of UV radiation by a protective layer of ozone molecules in the atmosphere
• Satellite studies suggest that the ozone layer has been gradually thinning since the mid-1970s
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Figure 56.29
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• Destruction of atmospheric ozone results mainly from chlorofluorocarbons (CFCs) produced by human activity
• CFCs contain chlorine, which reacts with ozone to make O2
• This decreases the amount of ozone in the atmosphere
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Chlorine atom
Sunlight
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CIO
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Figure 56.30
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• The ozone layer is thinnest over Antarctica and southern Australia, New Zealand, and South America
• Ozone levels have decreased 2–10% at mid-latitudes during the past 20 years
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Figure 56.31
September 1979 September 2009
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Figure 56.31a
September 1979
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Figure 56.31b
September 2009
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• Ozone depletion causes DNA damage in plants and poorer phytoplankton growth
• An international agreement signed in 1987 has resulted in a decrease in ozone depletion
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Concept 56.5: Sustainable development can improve human lives while conserving biodiversity
• The concept of sustainability helps ecologists establish long-term conservation priorities
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Sustainable Biosphere Initiative
• Sustainable development is development that meets the needs of people today without limiting the ability of future generations to meet their needs
• The goal of the Sustainable Biosphere Initiative is to define and acquire basic ecological information for responsible development, management, and conservation of Earth’s resources
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• Sustainable development requires connections between life sciences, social sciences, economics, and humanities
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Case Study: Sustainable Development in Costa Rica
• Costa Rica’s conservation of tropical biodiversity involves partnerships between the government, nongovernmental organizations (NGOs), and private citizens
• Human living conditions (infant mortality, life expectancy, literacy rate) in Costa Rica have improved along with ecological conservation
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Life expectancyInfant mortality
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Figure 56.32
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The Future of the Biosphere
• Our lives differ greatly from those of early humans, who hunted and gathered and painted on cave walls
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(a) Detail of animals in a 36,000- year-old cave painting, Lascaux, France
(b) A 30,000-year-old ivory carving of a water bird, found in Germany
(d) A young biologist holding a songbird
(c) Nature lovers on a wildlife- watching expedition
Figure 56.33
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(a) Detail of animals in a 36,000-year-oldcave painting, Lascaux, France
Figure 56.33a
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Figure 56.33b
(b) A 30,000-year-old ivory carving of a water bird, found in Germany
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(c) Nature lovers on a wildlife-watching expedition
Figure 56.33c
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Figure 56.33d
(d) A young biologist holding a songbird
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• Our behavior reflects remnants of our ancestral attachment to nature and the diversity of life—the concept of biophilia
• Our sense of connection to nature may motivate realignment of our environmental priorities
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Genetic diversity: source of variations that enablepopulations to adapt to environmental changes
Species diversity: important in maintaining structureof communities and food webs
Ecosystem diversity: provides life-sustaining servicessuch as nutrient cycling and waste decomposition
Figure 56.UN01
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Figure 56.UN02-1
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Figure 56.UN02-2