55 conservation text

8/14/2019 55 Conservation Text

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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for

Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 55

Conservation Biology and

Restoration Ecology


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Overview: The Biodiversity Crisis

Conservation biology integrates the following fieldsto 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 ofspecies

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 weand other species depend


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Concept 55.1: Human activities threaten

Earths 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 ecosystemdegradation by humans

Humans are threatening Earths 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

Community and ecosystem diversity

across the landscape of an entire region

Figure 55.2



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 orthroughout the biosphere



An endangered species

Is one that is in danger of becoming extinctthroughout its range

Threatened species

Are those that are considered likely to become

endangered in the foreseeable future



Conservation biologists are concerned about

species loss Because of a number of alarming statistics

regarding extinction and biodiversity



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 riverdolphin

(c) Javan

rhinocerosFigure 55.3ac



Ecosystem Diversity

Ecosystem diversity

Identifies the variety of ecosystems in thebiosphere

Is being affected by human activity


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Biodiversity and Human Welfare

Human biophilia

Allows us to recognize the value of biodiversityfor 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 fromplants

Figure 55.4


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The loss of species

Also means the loss of genes and geneticdiversity

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 biodiversitythroughout 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 toloss of biodiversity


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Introduced species that gain a foothold in a

new habitat Usually disrupt their adopted community

(a) Brown tree

snake, intro-

duced to Guam

in cargo

(b) Introduced kudzu thriving in South Carolina

Figure 55.6a, b


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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 populationsof certain game fish

Figure 55.7

Di i f I i N k


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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

S ll P l ti A h


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Small-Population Approach

Conservation biologists who adopt the small-

population approach

Study the processes that can cause very small

populations finally to become extinct

Th E i i V


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The Extinction Vortex

A small population is prone to positive-

feedback loops

That draw the population down an extinction

vortexSmall

population

InbreedingGenetic

drift

Lower

reproduction

Higher

mortality Loss of

genetic

variabilityReduction in

individual

fitness and

population

adaptability

Smaller

population

Figure 55.9


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The key factor driving the extinction vortex

Is the loss of the genetic variation necessary toenable evolutionary responses to

environmental change

C St d Th G t P i i Chi k d th


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Case Study: The Greater Prairie Chicken and theExtinction 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 bytransplanting birds from larger populations


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The declining population rebounded

Confirming that it had been on its way down anextinction vortex

EXPRIMENTResearchers 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 DNAfrom 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.

RESULTSAfter translocation (blue arrow), the viability of

eggs rapidly improved, and the population rebounded.

CONCLUSIONThe researchers concluded that lack of genetic

variation had started the Jasper County population of prairie

chickens down the extinction vortex.

Numberofmalebirds

(a) Population dynamics

(b) Hatching rate

200

150

100

50

0

1970 1975 1980 1985 1990 1995 2000

Year

Eggshatched(%)

100

90

80

70

60

50

40

30

1970-74 1975-79 1980-84 1985-89 1990 1993-97

Years

Figure 55.10

Mi i Vi bl P l ti Si


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Minimum Viable Population Size

The minimum viable population (MVP)

Is the minimum population size at which aspecies is able to sustain its numbers and

survive


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A population viability analysis (PVA)

Predicts a populations chances for survivalover a particular time

Factors in the MVP of a population

Effective Population Size


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Effective Population Size

A meaningful estimate of MVP

Requires a researcher to determine theeffective population size, which is based on the

breeding size of a population

Case Study: Analysis of Grizzly Bear Populations


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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 ofgrizzly 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

Num

berofindividuals

150

100

50

01973 1982 1991 2000

Females with cubs

Cubs

Year

Figure 55.12

Declining Population Approach


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Declining-Population Approach

The declining-population approach

Focuses on threatened and endangeredpopulations that show a downward trend,

regardless of population size

Emphasizes the environmental factors thatcaused a population to decline in the first place

Steps for Analysis and Intervention


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Steps for Analysis and Intervention

The declining-population approach

Requires that population declines be evaluatedon a case-by-case basis

Involves a step-by-step proactive conservation

strategy

Case Study: Decline of the Red Cockaded


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Case Study: Decline of the Red-CockadedWoodpecker

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 55.13ac


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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 torebound

Weighing Conflicting Demands


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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, andlandscapes


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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

Landscape Structure and Biodiversity


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Landscape Structure and Biodiversity

The structure of a landscape

Can strongly influence biodiversity


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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

Corridors That Connect Habitat Fragments


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Corridors That Connect Habitat Fragments

A movement corridor

Is a narrow strip of quality habitat connectingotherwise 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 sustainpopulations

Establishing Protected Areas


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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

Finding Biodiversity Hot Spots


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i di g iodive sity ot Spots

A biodiversity hot spot is a relatively small area

With an exceptional concentration of endemicspecies 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

Philosophy of Nature Reserves


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p y f

Nature reserves are biodiversity islands

In a sea of habitat degraded to varyingdegrees by human activity

One argument for extensive reserves

Is that large, far-ranging animals with low-

density populations require extensive habitats


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In some cases

The size of reserves is smaller than the actualarea needed to sustain a population

Biotic boundary for

short-term survival;

MVP is 50 individuals.

Biotic boundary for

long-term survival;

MVP is 500 individuals.

Grand Teton

National Park

Wyoming

Idaho

43

42

41

40

0 50 100

Kilometers

SnakeR

.

Yellowstone

NationalPark

Shoshone R.

Montana

Wyoming

Montana

Idaho

MadisonR.

GallatinR.

YellowstoneR.

Figure 55.18


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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 Ricas reserves.

Nicaragua

Costa

Rica

Panam

aNational park land

Buffer zone

PACIFIC OCEAN

CARIBBEAN SEA

Figure 55.19a, b


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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 forrecovery


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Whether a disturbance is natural or caused by

humans

Seems to make little difference in this size-

time relationship

Recoverytime(years)

(logscale)

104

1,000

100

10

1

103 102 101 1 10 100 1,000 104

Natural disasters

Human-caused disasters

Natural OR human-

caused disastersMeteor

strike

Groundwater

exploitationIndustrial

pollution

Urbanization Salination

Modern

agriculture FloodVolcanic

eruptionAcidrain

Forest

fire

Nuclear

bomb

Tsunami

Oilspill

Slash& burn

Land-slide

Tree

fallLightning

strike

Spatial scale (km2)(log scale)

Figure 55.21


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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


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Bioremediation

Is the use of living organisms to detoxifyecosystems

Biological Augmentation


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Biological augmentation

Uses organisms to add essential materials to adegraded ecosystem

Exploring Restoration


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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

Truckee River, Nevada. Kissimmee River, Florida.

Equator

Figure 55.22


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Tropical dry forest, Costa Rica. Succulent Karoo, South Africa.

Rhine River, Europe. Coastal Japan.Figure 55.22


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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 Earths resources?

Sustainable Biosphere Initiative


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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 Earths resources

Case Study: Sustainable Development in Costa


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Rica

Costa Ricas 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 ecologicalconservation

Infantm

ortality(per1,000livebirths)

200

150

100

50

0

1900 1950 2000

80

70

60

50

40

30

Year

Life expectancy

Infant mortality

Lifeexpectancy(years)

Figure 55.23

Biophilia and the Future of the Biosphere


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Our modern lives

Are very different from those of early humanswho hunted and gathered and painted on cave

walls

(a) Detail of animals in a Paleolithic mural, Lascaux, FranceFigure 55.24a


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But our behavior

Reflects remnants of our ancestral attachmentto nature and the diversity of life, the concept

of biophilia

(b) Biologist Carlos Rivera Gonzales examining a tiny tree frog in

PeruFigure 55.24b


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Our innate sense of connection to nature

May eventually motivate a realignment of ourenvironmental priorities

55 conservation text

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