Chapter 55

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell & Jane Reece

Lectures by Chris Romero

Chapter 55Chapter 55

Conservation Biology & Restoration Ecology


Overview: The Biodiversity Crisis

• Conservation biology integrates these fields:

– Ecology

– Evolutionary biology

– Physiology

– Molecular biology

– Genetics

– Behavioral ecology


• Restoration ecology applies ecological principles to return degraded ecosystems to cond’s as similar as possible to their natural state


• Tropical forests containing some of the greatest concentrations of spp are being destroyed at an alarming rate

• Throughout the biosphere, human activities are altering ecosystem processes on which we & other spp depend



Concept 55.1: Human activities threaten Earth’s biodiversity

• Rates of spp extinction are difficult to determine under natural conditions

• The high rate of spp extinction is largely a result of ecosystem degradation by humans

• Humans are threatening Earth’s biodiversity


The 3 Levels of Biodiversity

• Biodiversity- 3 main parts:

– Genetic diversity

– spp diversity

– Ecosystem diversity

LE 55-2LE 55-2

Genetic diversity in a vole pop

spp diversity in a coastal redwood ecosystem

Community & ecosystem diversityacross the landscape of an entire region


Genetic Diversity

• Genetic diversity- genetic variation w/in a pop & b/w pop's


spp Diversity

• spp diversity- variety of spp in an ecosystem or the biosphere

• endangered spp- danger of becoming extinct through its range

• threatened spp- likely to become endangered in the future


• Conservation biologists are concerned about spp loss because of alarming statistics regarding extinction & biodiversity

• Researchers estimate that at current rates of extinction more than ½ of current plant & animal spp will disappear in this century

• Harvard biologist E. O. Wilson has identified the Hundred Heartbeat Club: spp w/ fewer than 100 indiv's

LE 55-3LE 55-3Philippine eagle

Chinese riverdolphin

Javanrhinoceros


Ecosystem Diversity

• Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere


Biodiversity & Human Welfare

• Human biophilia allows us to recognize the value of biodiversity for its own sake

• spp diversity brings humans practical benefits


Benefits of spp & Genetic Diversity

• Many pharmaceuticals contain substances originally derived from plants

• For example, the rosy periwinkle contains alkaloids that inhibit cancer growth



• The loss of spp also means loss of genes & genetic diversity

• The enormous genetic diversity of organisms has potential for great human benefit


Ecosystem Services

• Ecosystem services encompass all the processes through which natural ecosystems & their spp help sustain human life

• Some examples of ecosystem services:

– Purification of air & water

– Detoxification & decomposition of wastes

– Cycling of nutrients

– Moderation of weather extremes


Four Major Threats to Biodiversity

• Most spp loss can be traced to four major threats:

– Habitat destruction

– Introduced spp

– Overexploitation

– Disruption of “interaction networks”


Habitat Destruction

• Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere

• Many natural landscapes have been broken up, fragmenting habitat into small patches

• In almost all cases, habitat fragmentation & destruction lead to loss of biodiversity



Introduced spp

• Introduced spp are those that humans move from native locations to new geographic regions

• Introduced spp that gain a foothold in a new habitat usually disrupt their adopted community


• Sometimes humans introduce spp by accident, as in case of the brown tree snake arriving in Guam as a cargo ship “stowaway”

LE 55-6LE 55-6Brown treesnake, intro-duced to Guamin cargo.

Introduced kudzu thriving in South Carolina


• Humans have deliberately introduced some spp w/ good intentions but disastrous effects

• An example is the introduction of kudzu in the southern United States


Overexploitation

• Overexploitation- human harvesting of wild plants or animals at rates exceeding the ability of pop's of those spp to rebound

• For example, the fishing industry has greatly reduced pop's of some game fish, such as bluefin tuna



Disruption of Interaction Networks

• Extermination of keystone spp by humans can lead to major changes in community structure



Concept 55.2: pop conservation focuses on pop size, genetic diversity, & critical habitat

• Biologists focusing on conservation at the pop & spp levels follow 2 main approaches:

– The small-population approach

– The declining pop approach


Small-Population Approach

• The small-pop approach studies processes that can make small pop's become extinct


The Extinction Vortex

• A small pop is prone to positive-feedback loops that draw it down an extinction vortex

LE 55-9LE 55-9

Reduction inindiv

fitness &pop

adaptability

Smallpop

Loss ofgenetic

variability

Highermortality

GeneticdriftInbreeding

Lowerreproduction

Smallerpop


• The key factor driving the extinction vortex is loss of the genetic variation necessary to enable evolutionary responses to environmental change


Case Study: The Greater Prairie Chicken & the Extinction Vortex

• pop's of the greater prairie chicken were fragmented by agriculture & later found to exhibit decreased fertility

• To test the extinction vortex hypothesis, scientists imported genetic variation by transplanting birds from larger pop's

• The declining pop rebounded, confirming it had been on its way down an extinction vortex

LE 55-10LE 55-10

pop dynamics

1970 1975 1980 1985 1990 1995 2000Year

# o

f m

ale

bir

ds

100

200

150

50

0

Hatching rate

1970–74

Years

Eg

gs

ha

tch

ed

(%

)

100

90

80

70

60

50

40

301975–79 1980–84 1985–89 1990 1993–97


Minimum Viable pop Size

• Minimum viable pop (MVP) is the minimum pop size at which a spp can survive

• The MVP factors into a pop viability analysis (PVA), which predicts a pop’s chances for survival over a particular time


Effective pop Size

• A meaningful estimate of MVP requires determining the effective pop size, which is based on the pop's breeding size


Case Study: Analysis of Grizzly Bear pop's

• One of the first pop viability analyses was conducted as part of a long-term study of grizzly bears in Yellowstone National Park



• This study showed that the grizzly bear pop has grown substantially in the past 20 years

LE 55-12LE 55-12

1973

Year

# o

f in

div

's150

100

50

01982 1991 2000

Females w/ cubs

Cubs


Declining-Population Approach

• The declining-population approach

– Focuses on threatened & endangered pop's that show a downward trend, regardless of pop size

– Emphasizes the environmental factors that caused a pop to decline


Steps for Analysis & Intervention

• The declining-population approach

– Requires that declines in pop be evaluated on a case-by-case basis

– Involves a step-by-step proactive conservation strategy


Case Study: Decline of the Red-Cockaded Woodpecker

• Red-cockaded woodpeckers had been forced into decline by habitat destruction

LE 55-13LE 55-13

A red-cockaded woodpecker perches at the entrance to its nest site in a longleaf pine.

Forest that can sustain red-cockaded woodpeckers has low undergrowth.

Forest that cannot sustain red-cockaded woodpeckers has high, dense undergrowth that impacts the woodpeckers’ access to feeding grounds.


• 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 & excavation of breeding cavities enabled this endangered spp to rebound


Weighing Conflicting Demands

• Conserving spp often requires resolving conflicts b/w habitat needs of endangered spp & human demands


Concept 55.3: Landscape & regional conservation aim to sustain entire biotas

• Conservation biology has attempted to sustain the biodiversity of entire communities, ecosystems, & landscapes

• Ecosystem management is part of landscape ecology, which seeks to make biodiversity conservation part of land-use planning


Landscape Structure & Biodiversity

• The structure of a landscape can strongly influence biodiversity


Fragmentation & Edges

• The boundaries, or edges, b/w ecosystems are defining features of landscapes

• Some edges are natural, but some are created by human activity

LE 55-14LE 55-14

Natural edges. Grasslands give way to forest ecosystems in Yellowstone National Park.

Edges created by human activity. Pronounced edges (roads) surround clear-cuts in this photograph of a heavily logged rain forest in Malaysia.


• Biodiversity ↓'s as habitat fragmentation ↑'s & edges become more extensive

• Research led to discovery of 2 groups of spp;

• those that live in forest edge habitats

• & those that live in forest interior



Corridors That Connect Habitat Fragments

• mvmt corridor- narrow strip of quality habitat connecting otherwise isolated patches

• Movement corridors promote dispersal & help sustain pop's

• In areas of heavy human use, artificial corridors are sometimes constructed



Establishing Protected Areas

• Conservation biologists apply understanding of ecological dynamics in establishing protected areas to slow the loss of biodiversity

• Much of their focus has been on hot spots of biological diversity


Finding Biodiversity Hot Spots

• biodiversity hot spot- relatively small area w/ a great concen of endemic spp & many endangered & threatened spp

• Biodiversity hot spots are good choices for nature reserves, but identifying them is not always easy

Video: Coral Reef

LE 55-17LE 55-17

Terrestrialbiodiversityhot spots

Equator


Philosophy of Nature Reserves

• Nature reserves are biodiversity islands in a sea of habitat degraded by human activity

• One argument for extensive reserves is that large, far-ranging animals w/ low-density pop's require extensive habitats

• In some cases, reserves are smaller than the area needed to sustain a pop

LE 55-18LE 55-18

Kilometers

0 50 100

43°

YellowstoneNational

Park

Mad

iso

n R

.

Idaho

MontanaG

all a

tin

R.

42°

41°

40°

Grand TetonNational Park

Wyoming

Snake R.

Montana

Idah

o

Wyo

min

g

Yellowstone R.

Shoshone R.


Zoned Reserves

• The zoned reserve model recognizes that conservation often involves working in landscapes that are largely human dominated

• Zoned reserves are often established as “conservation areas”

LE 55-19aLE 55-19a

National park land

Buffer zone

PACIFIC OCEAN

CARIBBEAN SEANicaragua

CostaRica

Panam

a

Boundaries of the zoned reserves are indicated by black outlines.

LE 55-19bLE 55-19b

Local schoolchildren marvel at the diversity of life in one of Costa Rica’s reserves.


• Some zoned reserves in the Fiji islands are closed to fishing, which actually improves fishing success in nearby areas



Concept 55.4: Restoration ecology attempts to restore degraded ecosystems to a more natural state

• Given enough time, biological communities can recover from many types of disturbances

• Recovery time depends more on the spatial scale than on the type of disturbance

• Whether a disturbance is natural or caused by humans seems to make little diff in this size-time relationship

LE 55-21LE 55-21

Natural disasters

GroundwaterexploitationIndustrial

pollution

Meteorstrike

Human-caused disasters

Natural OR human-caused disasters

104

1,000

100

Rec

ove

ry t

i me

( yea

rs)

( lo

g s

cale

)

10

1

10–3 10–110–2 1 104

Spatial scale (km2)(log scale)

1,00010010

Salination

Flood

Urbanization

TsunamiOil

spill

Modernagriculture

Forestfire

Nuclearbomb

Acidrain

Volcaniceruption

Lightningstrike

Treefall

Land-slide

Slash& burn


• A basic assumption of restoration ecology is that most environmental damage is reversible

• 2 key strategies:

• bioremediation &

• augmentation of ecosystem processes


Bioremediation

• Bioremediation- 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 & complexity of restoration ecology require considering alternative solns & adjusting approaches based on experience









Concept 55.5: Sustainable development seeks to improve the human condition while conserving biodiversity

• Facing increasing loss & fragmentation of habitats, how can we manage Earth’s resources?


Sustainable Biosphere Initiative

• The goal of the Sustainable Biosphere Initiative is to define & acquire basic ecological info for responsible development, management, & conservation of Earth’s resources

• Sustainable development is the long-term prosperity of human societies & the ecosystems that support them


Case Study: Sustainable Development in Costa Rica

• Costa Rica’s conservation of tropical biodiversity involves partnerships b/w the government, other organizations, & private citizens

• Human living conditions in Costa Rica have improved along w/ ecological conservation

LE 55-23LE 55-23

Life expectancy

Infa

nt

mo

rtal

i ty

(per

1,0

00 l

i ve

bi r

ths)

Li f

e ex

pe c

tan

cy (

yea r

s)

Infant mortality

80

70

60

50

40

30

200

1900

150

100

50

0

1950 2000

Year


Biophilia & the Future of the Biosphere

• Our lives differ greatly from early humans who hunted & gathered & painted on cave walls

LE 55-24LE 55-24

Detail of animals in a 36,000-year-old cave painting, Lascaux, France Biologist Carlos Rivera Gonzales examining a tiny tree frog in Peru


• But our behavior reflects remnants of our ancestral attachment to nature & 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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Chapter 55