chapter 8 population ecology. chapter overview questions what are the major characteristics of...

Chapter 8Chapter 8

Population EcologyPopulation Ecology

Chapter Overview QuestionsChapter Overview Questions

What are the major characteristics of What are the major characteristics of populations?populations?

How do populations respond to changes in How do populations respond to changes in environmental conditions?environmental conditions?

How do species differ in their reproductive How do species differ in their reproductive patterns?patterns?

They were over-They were over-hunted to the hunted to the brink of extinction brink of extinction by the early by the early 1900’s and are 1900’s and are now making a now making a comeback.comeback.

Core Case Study: Core Case Study: Southern Sea Otters: Are They Back Southern Sea Otters: Are They Back

from the Brink of Extinction?from the Brink of Extinction?

Figure 8-1Figure 8-1

Core Case Study: Core Case Study: Southern Sea Otters: Are They Back Southern Sea Otters: Are They Back

from the Brink of Extinction?from the Brink of Extinction?

Sea otters are an Sea otters are an important important keystone species keystone species for sea urchins for sea urchins and other kelp-and other kelp-eating organisms.eating organisms.


POPULATION DYNAMICS AND POPULATION DYNAMICS AND CARRYING CAPACITYCARRYING CAPACITY

Most populations live in clumps although other Most populations live in clumps although other patterns occur based on resource distribution.patterns occur based on resource distribution.


Fig. 8-2a, p. 162(a) Clumped (elephants)

Fig. 8-2b, p. 162(b) Uniform (creosote bush)

Fig. 8-2c, p. 162(c) Random (dandelions)

Changes in Population Size: Changes in Population Size: Entrances and ExitsEntrances and Exits

Populations increase through births and Populations increase through births and immigrationimmigration

Populations decrease through deaths and Populations decrease through deaths and emigrationemigration

Age Structure: Young Populations Age Structure: Young Populations Can Grow FastCan Grow Fast

How fast a population grows or declines How fast a population grows or declines depends on its age structure.depends on its age structure. Prereproductive agePrereproductive age: not mature enough to : not mature enough to

reproduce.reproduce. Reproductive ageReproductive age: those capable of : those capable of

reproduction.reproduction. Postreproductive agePostreproductive age: those too old to : those too old to

reproduce.reproduce.

Limits on Population Growth: Limits on Population Growth: Biotic Potential vs. Environmental Biotic Potential vs. Environmental

ResistanceResistance

No population can increase its size No population can increase its size indefinitely.indefinitely. The intrinsic rate of increase (The intrinsic rate of increase (rr) is the rate at ) is the rate at

which a population would grow if it had unlimited which a population would grow if it had unlimited resources.resources.

Carrying capacity (Carrying capacity (KK): the maximum population ): the maximum population of a given species that a particular habitat can of a given species that a particular habitat can sustain indefinitely without degrading the habitat.sustain indefinitely without degrading the habitat.

Exponential and Logistic Population Exponential and Logistic Population Growth: J-Curves and S-CurvesGrowth: J-Curves and S-Curves

Populations Populations grow rapidly with grow rapidly with ample ample resources, but resources, but as resources as resources become limited, become limited, its growth rate its growth rate slows and levels slows and levels off.off.


Fig. 8-3, p. 163

EnvironmentalResistance

Time (t)

Po

pu

lat i

on

si z

e (N

)

Carrying capacity (K)

ExponentialGrowth

BioticPotential

Animation: Exponential GrowthAnimation: Exponential Growth

PLAYANIMATION

Video: Logistic GrowthVideo: Logistic Growth

PLAYVIDEO

Exponential and Logistic Population Exponential and Logistic Population Growth: J-Curves and S-CurvesGrowth: J-Curves and S-Curves

As a population As a population levels off, it levels off, it often fluctuates often fluctuates slightly above slightly above and below the and below the carrying carrying capacity.capacity.


Fig. 8-4, p. 164

Carrying capacity

Year

Nu

mb

er o

f sh

eep

(m

illi

on

s)Overshoot

Exceeding Carrying Capacity: Move, Exceeding Carrying Capacity: Move, Switch Habits, or Decline in SizeSwitch Habits, or Decline in Size

Members of Members of populations which populations which exceed their exceed their resources will die resources will die unless they adapt or unless they adapt or move to an area with move to an area with more resources.more resources.


Fig. 8-6, p. 165

Nu

mb

er o

f re

ind

eer

Populationovershootscarryingcapacity

Carryingcapacity

Year

PopulationCrashes

Exceeding Carrying Capacity: Move, Exceeding Carrying Capacity: Move, Switch Habits, or Decline in SizeSwitch Habits, or Decline in Size

Over time species may increase their Over time species may increase their carrying capacity by developing adaptations.carrying capacity by developing adaptations.

Some species maintain their carrying Some species maintain their carrying capacity by migrating to other areas.capacity by migrating to other areas.

So far, technological, social, and other So far, technological, social, and other cultural changes have extended the earth’s cultural changes have extended the earth’s carrying capacity for humans.carrying capacity for humans.

Population Density and Population Population Density and Population Change: Effects of CrowdingChange: Effects of Crowding

Population density: the number of individuals Population density: the number of individuals in a population found in a particular area or in a population found in a particular area or volume.volume. A population’s density can affect how rapidly it A population’s density can affect how rapidly it

can grow or decline.can grow or decline.• e.g. biotic factors like diseasee.g. biotic factors like disease

Some population control factors are not affected Some population control factors are not affected by population density.by population density.• e.g. abiotic factors like weathere.g. abiotic factors like weather

Types of Population Change Types of Population Change Curves in NatureCurves in Nature

Population sizes may stay the same, increase, Population sizes may stay the same, increase, decrease, vary in regular cycles, or change decrease, vary in regular cycles, or change erratically.erratically. StableStable: fluctuates slightly above and below carrying : fluctuates slightly above and below carrying

capacity.capacity. IrruptiveIrruptive: populations explode and then crash to a : populations explode and then crash to a

more stable level.more stable level. CyclicCyclic: populations fluctuate and regular cyclic or : populations fluctuate and regular cyclic or

boom-and-bust cycles.boom-and-bust cycles. IrregularIrregular: erratic changes possibly due to chaos or : erratic changes possibly due to chaos or

drastic change. drastic change.

Types of Population Change Types of Population Change Curves in NatureCurves in Nature

Population sizes often vary in regular cycles Population sizes often vary in regular cycles when the predator and prey populations are when the predator and prey populations are controlled by the scarcity of resources.controlled by the scarcity of resources.


Fig. 8-7, p. 166

Po

pu

lati

on

siz

e (t

ho

usa

nd

s)

Year

LynxHare

Animation: Capture-Recapture Animation: Capture-Recapture Method Method

PLAYANIMATION

Case Study: Exploding White-Tailed Case Study: Exploding White-Tailed Deer Populations in the United StatesDeer Populations in the United States

Since the 1930s the white-tailed deer Since the 1930s the white-tailed deer population has exploded in the United States.population has exploded in the United States. Nearly extinct prior to their protection in 1920’s.Nearly extinct prior to their protection in 1920’s.

Today 25-30 million white-tailed deer in U.S. Today 25-30 million white-tailed deer in U.S. pose human interaction problems.pose human interaction problems. Deer-vehicle collisions (1.5 million per year).Deer-vehicle collisions (1.5 million per year). Transmit disease (Lyme disease in deer ticks).Transmit disease (Lyme disease in deer ticks).

REPRODUCTIVE PATTERNSREPRODUCTIVE PATTERNS

Some species reproduce without having sex Some species reproduce without having sex (asexual).(asexual). Offspring are exact genetic copies (clones).Offspring are exact genetic copies (clones).

Others reproduce by having sex (sexual).Others reproduce by having sex (sexual). Genetic material is mixture of two individuals.Genetic material is mixture of two individuals. Disadvantages: males do not give birth, increase Disadvantages: males do not give birth, increase

chance of genetic errors and defects, courtship chance of genetic errors and defects, courtship and mating rituals can be costly.and mating rituals can be costly.

Major advantages: genetic diversity, offspring Major advantages: genetic diversity, offspring protection.protection.

Sexual Reproduction: CourtshipSexual Reproduction: Courtship

Courtship rituals Courtship rituals consume time and consume time and energy, can transmit energy, can transmit disease, and can disease, and can inflict injury on males inflict injury on males of some species as of some species as they compete for they compete for sexual partners.sexual partners.


Reproductive Patterns:Reproductive Patterns:Opportunists and CompetitorsOpportunists and Competitors

Large number of Large number of smaller offspring with smaller offspring with little parental care (r-little parental care (r-selected species).selected species).

Fewer, larger Fewer, larger offspring with higher offspring with higher invested parental invested parental care (K-selected care (K-selected species).species).


Fig. 8-9, p. 168

r species;experiencer selection

Time

Nu

mb

er o

f in

div

idu

als

KCarrying capacity

K species;experienceK selection

Reproductive PatternsReproductive Patterns

r-selected species tend to be opportunists r-selected species tend to be opportunists while K-selected species tend to be while K-selected species tend to be competitors.competitors.


Fig. 8-10a, p. 168

Many small offspring

Little or no parental care and protection of offspring

Early reproductive age

Most offspring die before reaching reproductive age

Small adults

Adapted to unstable climate and environmental conditions

High population growth rate (r)

Population size fluctuates wildly above and below carrying capacity (K)

Generalist niche

Low ability to compete

Early successional species

r-Selected SpeciesCockroach

Dandelion

Fig. 8-10b, p. 168

Fewer, larger offspring

High parental care and protection of offspring

Later reproductive age

Most offspring survive to reproductive age

Larger adults

Adapted to stable climate and environmental conditions

Lower population growth rate (r)

Population size fairly stable and usually close to carrying capacity (K)

Specialist niche

High ability to compete

Late successional species

K-Selected Species

SaguaroElephant

Survivorship Curves: Survivorship Curves: Short to Long LivesShort to Long Lives

The way to represent the age structure of a The way to represent the age structure of a population is with a population is with a survivorship curvesurvivorship curve.. Late loss populationLate loss population live to an old age. live to an old age. Constant loss populationConstant loss population die at all ages. die at all ages. Most members of Most members of early loss populationearly loss population, die at , die at

young ages.young ages.

Survivorship Curves: Survivorship Curves: Short to Long LivesShort to Long Lives

The populations The populations of different of different species vary in species vary in how long how long individual individual members typically members typically live.live.


Fig. 8-11, p. 169

Per

cen

tag

e su

rviv

ing

(lo

g s

cale

)

Age

Early loss

Late loss

Constant loss

Animation: Life History PatternsAnimation: Life History Patterns

PLAYANIMATION

Chapter 11Chapter 11

Sustaining Biodiversity: Sustaining Biodiversity: The Species ApproachThe Species Approach

Chapter Overview QuestionsChapter Overview Questions

How do biologists estimate extinction rates, How do biologists estimate extinction rates, and how do human activities affect these and how do human activities affect these rates?rates?

Why should we care about protecting wild Why should we care about protecting wild species?species?

Which human activities endanger wildlife?Which human activities endanger wildlife? How can we help prevent premature How can we help prevent premature

extinction of species?extinction of species? What is reconciliation ecology, and how can it What is reconciliation ecology, and how can it

help prevent premature extinction of species?help prevent premature extinction of species?

Core Case Study: Core Case Study: The Passenger Pigeon - Gone The Passenger Pigeon - Gone

ForeverForever Once the most Once the most

numerous bird on earth.numerous bird on earth. In 1858, Passenger In 1858, Passenger

Pigeon hunting became Pigeon hunting became a big business.a big business.

By 1900 they became By 1900 they became extinct from over-extinct from over-harvest and habitat harvest and habitat loss.loss.


Animation: Humans Affect BiodiversityAnimation: Humans Affect Biodiversity

PLAYANIMATION

SPECIES EXTINCTIONSPECIES EXTINCTION

Species can become extinct: Species can become extinct: LocallyLocally: A species is no longer found in an area : A species is no longer found in an area

it once inhabited but is still found elsewhere in it once inhabited but is still found elsewhere in the world.the world.

EcologicallyEcologically: Occurs when so few members of a : Occurs when so few members of a species are left they no longer play its ecological species are left they no longer play its ecological role.role.

Globally (biologically)Globally (biologically): Species is no longer : Species is no longer found on the earth.found on the earth.

Global ExtinctionGlobal Extinction

Some animals have become prematurely Some animals have become prematurely extinct because of human activities.extinct because of human activities.


Fig. 11-2, p. 223

Aepyornis(Madagascar)

Passenger pigeon Great auk Dodo Dusky seaside sparrow

Endangered and Threatened Species: Endangered and Threatened Species: Ecological Smoke AlarmsEcological Smoke Alarms

Endangered speciesEndangered species: so few individual : so few individual survivors that it could soon become extinct.survivors that it could soon become extinct.

Threatened speciesThreatened species: still abundant in its : still abundant in its natural range but is likely to become natural range but is likely to become endangered in the near future.endangered in the near future.


Fig. 11-3, p. 224

Some species Some species have have characteristics characteristics that make them that make them vulnerable to vulnerable to ecological and ecological and biological biological extinction.extinction.

SPECIES SPECIES EXTINCTIONEXTINCTION


Fig. 11-4, p. 225

Low reproductive rate(K-strategist)

Specialized niche

Narrow distribution

Feeds at high trophic level

Fixed migratory patterns

Rare

Commercially valuable

Large territories

Characteristic

Blue whale, giant panda,rhinoceros

Blue whale, giant panda,Everglades kite

Many island species,elephant seal, desert pupfish

Bengal tiger, bald eagle,grizzly bear

Blue whale, whooping crane,sea turtles

Many island species,African violet, some orchids

Snow leopard, tiger, elephant, rhinoceros, rare plants and birds

California condor, grizzly bear, Florida panther

Examples


Scientists use measurements and models to Scientists use measurements and models to estimate extinction rates.estimate extinction rates. The International Union for the Conservation of The International Union for the Conservation of

Nature and Natural Resources (IUCN) publishes Nature and Natural Resources (IUCN) publishes an annual an annual Red ListRed List, listing the world’s threatened , listing the world’s threatened species.species.

The 2004 Red List contains 15,589 species at The 2004 Red List contains 15,589 species at risk for extinction.risk for extinction.


Video: Penguin RescueVideo: Penguin Rescue

From ABC News, Biology in the Headlines, 2005 DVD.From ABC News, Biology in the Headlines, 2005 DVD.

PLAYVIDEO


Percentage of various species types Percentage of various species types threatened with premature extinction from threatened with premature extinction from human activities.human activities.


Fig. 11-5, p. 225

12%Birds

Plants

Reptiles

Mammals

Fish 34% (51% of freshwater species)

25%

20%

14%


Scientists use Scientists use models to models to estimate the risk estimate the risk of particular of particular species becoming species becoming extinct or extinct or endangered.endangered.


Fig. 11-6, p. 226

5 million

Number of years until one millionspecies are extinct

100,000 extinct per year



Numberof speciesexisting Effects of a 0.1% extinction rate


100 million

50 million

14 million

IMPORTANCE OF WILD SPECIES IMPORTANCE OF WILD SPECIES We should not cause the premature We should not cause the premature

extinction of species because of the extinction of species because of the economic and ecological services they economic and ecological services they provide.provide.

Some believe that each wild species has an Some believe that each wild species has an inherent right to exist.inherent right to exist. Some people distinguish between the survival Some people distinguish between the survival

rights among various types of species (plants vs. rights among various types of species (plants vs. animals).animals).

HABITAT LOSS, DEGRADATION, HABITAT LOSS, DEGRADATION, AND FRAGMENTATIONAND FRAGMENTATION

Conservation biologists summarize the most Conservation biologists summarize the most important causes of premature extinction as important causes of premature extinction as “HIPPO”: “HIPPO”: Habitat destruction, degradation, and Habitat destruction, degradation, and

fragmentationfragmentation Invasive speciesInvasive species Population growthPopulation growth PollutionPollution OverharvestOverharvest

Animation: Habitat Loss and Animation: Habitat Loss and FragmentationFragmentation

PLAYANIMATION


The greatest threat to a species is the loss, The greatest threat to a species is the loss, degradation, and fragmentation of where it lives.degradation, and fragmentation of where it lives.


Fig. 11-7, p. 229

Introducing nonnative species

Basic Causes

Secondary Causes

• Population growth• Rising resource use • No environmental

accounting• Poverty

Predator and pest control

Climate change

Overfishing Pollution

Commercial hunting and poaching

Sale of exotic pets and decorative plants

Habitatloss

Habitat degradationand fragmentation


Reduction in Reduction in ranges of four ranges of four wildlife species, wildlife species, mostly due to mostly due to habitat loss habitat loss and and overharvest.overharvest.


Fig. 11-8a, p. 230

Range 100 years ago

Indian Tiger

Range today(about 2,300 left)

Fig. 11-8b, p. 230

Range in 1700

Black Rhino

Range today(about 3,600 left)

Fig. 11-8c, p. 230

Probable range 1600

African Elephant

Range today

Fig. 11-8d, p. 230

Range today(34,000–54,000 left)

Asian or Indian Elephant

Former range

Video: Bachelor Pad at the ZooVideo: Bachelor Pad at the Zoo


PLAYVIDEO

Case Study: Case Study: A Disturbing Message from the BirdsA Disturbing Message from the Birds

Human activities are causing serious declines Human activities are causing serious declines in the populations of many bird species.in the populations of many bird species.


Fig. 11-10, p. 232

Bachman’s warbler

Cerulean warbler Sprague’s pipit Bichnell’s thrush Black-capped vireo

Golden-cheeked warbler

Florida scrub jay California gnatcatcher

Kirtland’s warbler Henslow’s sparrow

Video: Bird Species and BirdsongsVideo: Bird Species and Birdsongs

PLAYVIDEO

Case Study: Case Study: A Disturbing Message from the BirdsA Disturbing Message from the Birds

The majority of the The majority of the world’s bird species are world’s bird species are found in South found in South America.America. Threatened with habitat Threatened with habitat

loss and invasive loss and invasive species.species.


Fig. 11-9, p. 2311

609

Number ofbird species

400

200

INVASIVE SPECIESINVASIVE SPECIES

Many nonnative Many nonnative species provide us species provide us with food, medicine, with food, medicine, and other benefits and other benefits but a a few can wipe but a a few can wipe out native species, out native species, disrupt ecosystems, disrupt ecosystems, and cause large and cause large economic losses.economic losses.

Kudzu vine was introduced in Kudzu vine was introduced in the southeastern U.S. to the southeastern U.S. to control erosion. It has taken control erosion. It has taken over native species habitats.over native species habitats.

Figure 11-AFigure 11-A


Many invasive species have been introduced Many invasive species have been introduced intentionally.intentionally.


Fig. 11-11a, p. 234

Deliberately Introduced Species

Purple loosestrife European starling African honeybee(“Killer bee”)

Nutria Salt cedar(Tamarisk)

European wild boar(Feral pig)

Marine toad(Giant toad)

Water hyacinth Japanese beetle

Hydrilla


Many invasive species have been introduced Many invasive species have been introduced unintentionally.unintentionally.


Fig. 11-11b, p. 234

Gypsy moth larvae

Accidentally Introduced Species

Sea lamprey(attached to lake trout)

Argentina fire ant

Brown tree snake

Eurasian ruffe Common pigeon(Rock dove)

Formosan termite Zebra mussel Asian long-horned beetle

Asian tiger mosquito

Fig. 11-11, p. 234


The Argentina fire The Argentina fire ant was introduced ant was introduced to Mobile, Alabama to Mobile, Alabama in 1932 from South in 1932 from South America.America. Most probably from Most probably from

ships.ships. No natural No natural

predators.predators.


INVASIVE INVASIVE SPECIESSPECIES

Prevention is the Prevention is the best way to reduce best way to reduce threats from threats from invasive species, invasive species, because once they because once they arrive it is almost arrive it is almost impossible to slow impossible to slow their spread.their spread.


Fig. 11-14, p. 236

• Do not allow wild animals to escape.

• Do not spread wild plants to other areas.

• Do not dump the contents of an aquarium into waterways, wetlands, or storm drains.

• When camping use wood near your campsite instead of bringing firewood from somewhere else.

• Do not dump unused bait into the water.

• After dogs visit woods or the water brush them before taking them home.

• After each use clean your vehicle, mountain bike, surfboard, kayaks, canoes, boats, tent, hiking boots, and other gear before heading for home.

• Empty all water from canoes, kayaks, dive gear, and other outdoor equipment before heading home.

• Plant a variety of trees, shrubs, and other plants in your yard to reduce losses from invasive species.

• Do not buy plants from overseas or swap them with others using the Internet.

What Can You Do?

Invasive Species

Fig. 11-13, p. 236

• Climate similar to habitat of invader

• Absence of predators on invading species

• Early successional systems

• Low diversity of native species

• Absence of fire

• Disturbed by human activities

Characteristics ofSuccessful

Invader Species

• High reproductive rate, short generation time (r-selected species)

• Pioneer species

• Long lived

• High dispersal rate

• Release growth-inhibiting chemicals into soil

• Generalists

• High genetic variability

Characteristics ofEcosystems Vulnerable

to Invader Species

POPULATION GROWTH, POPULATION GROWTH, POLLUTION, AND CLIMATE POLLUTION, AND CLIMATE

CHANGECHANGE

Population growth, affluenza, and pollution Population growth, affluenza, and pollution have promoted the premature extinction of have promoted the premature extinction of some species.some species.

Projected climate change threatens a number Projected climate change threatens a number of species with premature extinction.of species with premature extinction.

PollutionPollution Each year pesticides:Each year pesticides:

Kill about 1/5Kill about 1/5thth of the of the U.S. honeybee U.S. honeybee colonies.colonies.

67 million birds.67 million birds. 6 -14 million fish.6 -14 million fish. Threaten 1/5Threaten 1/5thth of the of the

U.S.’s endangered U.S.’s endangered and threatened and threatened species.species.

Example of biomagnification Example of biomagnification of DDT in an aquatic food of DDT in an aquatic food chain.chain.


Fig. 11-15, p. 237

DDT in water 0.000003 ppm, or 3 ppt

DDT in fish-eating birds (ospreys)

25 ppm

DDT in large fish (needle fish) 2 ppm

DDT in small fish (minnows) 0.5 ppm

DDT in zooplankton 0.04 ppm

OVEREXPLOITATIONOVEREXPLOITATION

Some protected species are killed for their Some protected species are killed for their valuable parts or are sold live to collectors.valuable parts or are sold live to collectors.

Killing predators and pests that bother us or Killing predators and pests that bother us or cause economic losses threatens some cause economic losses threatens some species with premature extinction.species with premature extinction.

Legal and illegal trade in wildlife species Legal and illegal trade in wildlife species used as pets or for decorative purposes used as pets or for decorative purposes threatens some species with extinction.threatens some species with extinction.

PROTECTING WILD SPECIES: PROTECTING WILD SPECIES: LEGAL AND ECONOMIC LEGAL AND ECONOMIC

APPROACHESAPPROACHES International treaties have helped reduce the International treaties have helped reduce the

international trade of endangered and international trade of endangered and threatened species, but enforcement is threatened species, but enforcement is difficult.difficult. One of the most powerful is the 1975 Convention One of the most powerful is the 1975 Convention

on International Trade of Endangered Species on International Trade of Endangered Species (CITES).(CITES).• Signed by 169 countries, lists 900 species that cannot Signed by 169 countries, lists 900 species that cannot

be commercially traded.be commercially traded.

Case Study: Case Study: The U.S. Endangered Species ActThe U.S. Endangered Species Act

One of the world’s most far-reaching and One of the world’s most far-reaching and controversial environmental laws is the 1973 controversial environmental laws is the 1973 U.S. Endangered Species Act (ESA).U.S. Endangered Species Act (ESA). ESA forbids federal agencies (besides defense ESA forbids federal agencies (besides defense

department) to carry out / fund projects that department) to carry out / fund projects that would jeopardize an endangered species.would jeopardize an endangered species.

ESA makes it illegal for Americans to engage in ESA makes it illegal for Americans to engage in commerce associated with or hunt / kill / collect commerce associated with or hunt / kill / collect endangered or threatened species.endangered or threatened species.

Case Study: Case Study: The U.S. Endangered Species ActThe U.S. Endangered Species Act

Biodiversity hotspots in relation to the largest Biodiversity hotspots in relation to the largest concentrations of rare and potentially concentrations of rare and potentially endangered species in the U.S.endangered species in the U.S. Figure 11-18Figure 11-18

Fig. 11-18, p. 241

Top Six Hot Spots1 Hawaii2 San Francisco Bay

area3 Southern

Appalachians4 Death Valley5 Southern California6 Florida Panhandle

Concentration of rare species

High Low Moderate

Endangered SpeciesEndangered Species

Because of Because of scarcity of scarcity of inspectors, inspectors, probably no probably no more than 1/10more than 1/10thth of the illegal of the illegal wildlife trade in wildlife trade in the U.S. is the U.S. is discovered.discovered.


Endangered SpeciesEndangered Species

Congress has amended the ESA to help Congress has amended the ESA to help landowners protect species on their land.landowners protect species on their land.

Some believe that the ESA should be Some believe that the ESA should be weakened or repealed while others believe it weakened or repealed while others believe it should be strengthened and modified to should be strengthened and modified to focus on protecting ecosystems.focus on protecting ecosystems.

Many scientists believe that we should focus Many scientists believe that we should focus on protecting and sustaining biodiversity and on protecting and sustaining biodiversity and ecosystem function as the best way to ecosystem function as the best way to protect species.protect species.

PROTECTING WILD SPECIES: THE PROTECTING WILD SPECIES: THE SANCTUARY APPROACHSANCTUARY APPROACH

The U.S. has set aside 544 The U.S. has set aside 544 federal refuges for wildlife, federal refuges for wildlife, but many refuges are but many refuges are suffering from environmental suffering from environmental degradation.degradation.

Pelican Island was the Pelican Island was the nation’s first wildlife refuge.nation’s first wildlife refuge.


PROTECTING WILD SPECIES: THE PROTECTING WILD SPECIES: THE SANCTUARY APPROACHSANCTUARY APPROACH

Gene banks, botanical gardens and using Gene banks, botanical gardens and using farms to raise threatened species can help farms to raise threatened species can help prevent extinction, but these options lack prevent extinction, but these options lack funding and storage space.funding and storage space.

Zoos and aquariums can help protect Zoos and aquariums can help protect endangered animal species by preserving endangered animal species by preserving some individuals with the long-term goal of some individuals with the long-term goal of reintroduction, but suffer from lack of space reintroduction, but suffer from lack of space and money. and money.

Video: Hsing Hsing DiesVideo: Hsing Hsing Dies


PLAYVIDEO

RECONCILIATION ECOLOGYRECONCILIATION ECOLOGY

Reconciliation ecology involves finding ways Reconciliation ecology involves finding ways to share places we dominate with other to share places we dominate with other species.species. Replacing monoculture grasses with native Replacing monoculture grasses with native

species.species. Maintaining habitats for insect eating bats can Maintaining habitats for insect eating bats can

keep down unwanted insects.keep down unwanted insects. Reduction and elimination of pesticides to protect Reduction and elimination of pesticides to protect

non-target organisms (such as vital insect non-target organisms (such as vital insect pollinators).pollinators).

Using Reconciliation Ecology to Using Reconciliation Ecology to Protect BluebirdsProtect Bluebirds

Putting up bluebird Putting up bluebird boxes with holes too boxes with holes too small for (nonnative) small for (nonnative) competitors in areas competitors in areas where trees have where trees have been cut down have been cut down have helped reestablish helped reestablish populations.populations.

Figure 11-BFigure 11-B

Fig. 11-21, p. 246

• Do not buy furs, ivory products, and other materials made from endangered or threatened animal species.

• Do not buy wood and paper products produced by cutting remaining old-growth forests in the tropics.

• Do not buy birds, snakes, turtles, tropical fish, and other animals that are taken from the wild.

• Do not buy orchids, cacti, and other plants that are taken from the wild.

• Spread the word. Talk to your friends and relatives about this problem and what they can do about it.

What Can You Do?

Protecting Species

chapter 8 population ecology. chapter overview questions what are the major characteristics of...

Documents

population levels

population change

population dynamics

maximum population

logistic population

populations density

growth rate

young populations