Chapter 55 ~ Conservation Biology. Overview: The Biodiversity Crisis –Conservation biology...

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