Populations

OVERVIEW

• Population: all the individuals of one species in a given area

• HOW POPULATIONS GROW – Exponential vs. logistic– r VS. K– Carrying Capacity

• Human Population Statistics– Predictions

• Impact on Conservation

Fig. 9.4, p. 201

Time (t)

Po

pu

lati

on

siz

e (N

)

Exponential Growth

Exponential Growth

• Biotic Potential – Pop. Grows as fast as physiology allows.

• Unlimited resources• No pollution build up• Ideal conditions• Short lived period• Often quickly die out,

colonize new areas• R selected species

Fig. 9.4, p. 201

Time (t)P

op

ula

tio

n s

ize

(N)

K

Logistic Growth

Logistic Growth• Slower initial

growth• Long –term stable

pop. At carrying capacity (K).

• K is size of pop. Area can sustain.

• Growth slowed by limiting factors

Fig. 8-3, p. 163

EnvironmentalResistance

Time (t)

Po

pu

lat i

on

si z

e (N)

Carrying capacity (K)

ExponentialGrowth

BioticPotential

Fig. 8-4, p. 164

Carrying capacity

Year

Nu

mb

er o

f sh

eep

(m

illi

on

s)Overshoot

Fig. 8-11, p. 169

Per

cen

tag

e su

rviv

ing

(lo

g s

cale

)

Age

Early loss

Late loss

Constant loss

Reproductive Patterns

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

Figure 8-10Figure 8-10

Fig. 8-6, p. 165

Nu

mb

er o

f re

ind

eer

Populationovershootscarryingcapacity

Carryingcapacity

Year

PopulationCrashes

Fig. 8-7, p. 166

Po

pu

lati

on

siz

e (t

ho

usa

nd

s)

Year

LynxHare

Fig. 9.9, p. 204

5,000

4,000

3,000

2,000

1,000

500

Nu

mb

er o

f m

oo

se

100

90

80

70

60

50

40

30

20

10

01900 1910 1930 1950 1970 1990 2000

1997Year

Nu

mb

er of w

olves

Moose population

Wolf population

Fig. 1.1, p. 2

16

15

14

13

12

11 Billio

ns o

f peo

ple

?

?

?

10

9

8

7

6

5

4

3

2

1

02-5 million

years8000 6000 4000 2000 2000 2100

Hunting and gathering

Black Death–the Plague

Time

Industrialrevolution

Agricultural revolution

B.C. A.D.

Fig. 9-3, p. 174

Average crude death rate

Average crude birth rate

World21

9

All developedcountries

11

10

All developingcountries

27

8

9

23

Developingcountries

(w/o China)

Fig. 11.8, p. 242

Births per woman

< 2

2-2.9

3-3.9

4-4.9

5+

Data notavailable

Fig. 9-3, p. 174

14

Europe

North America

UnitedStates

Oceania

Asia

Africa

Latin andCentral America

38

15

21

6

20

7

17

7

14

8

8

11

10

Fig. 9-4, p. 1742025

1.5 billionChina 1.3 billion

India 1.1 billion1.4 billion

USA 300 million349 million

Indonesia 225 million264 million

Brazil 187 million229 million

Pakistan 166 million229 million

Bangladesh 147 million190 million

Russia 142 million130 million

135 millionNigeria199 million

Japan121 million128 million

2006

GNP per capita, 1998

Low income (Under $1,000)

Middle income ($1,000–$10,000)

High income (Above $10,000)

Fig. 1.5, p. 9

Fig. 9-5, p. 175

ReplacementLevel

Year

Bir

ths

per

wo

man

Baby boom(1946–64)

Fig. 9-7, p. 176

47 years

Homicides per100,000 people

Hourly manufacturing job wage (adjusted for inflation)

Living insuburbs

Homes withelectricity

Homes withflush toilets

High schoolgraduates

Married women workingoutside the home

Life expectancy

1.25.8

$15$3

52%10%

99%2%

98%10%

83%15%

81%

2000

1900

8%

77 years

Fig. 9-8, p. 178

1907

Year

Nu

mb

er o

f le

gal

im

mig

ran

ts (

tho

usa

nd

s)

New lawsrestrictImmigration

1914

GreatDepression

Fig. 9-9, p. 179

Expanding RapidlyGuatemala

NigeriaSaudi Arabia

Expanding SlowlyUnited States

AustraliaCanada

StableSpain

PortugalGreece

DecliningGermanyBulgaria

ItalyPrereproductive ages 0–14 Reproductive ages 15–

44Postreproductive ages 45–85+

FemaleMale Male Male Male FemaleFemaleFemale

Fig. 9-11, p. 180

Females Males

Age

Females Males

Age

Females Males

Age

Females Males

Age

1955 1985 2015 2035

Fig. 9-15, p. 186

Total fertility rate

Percentageof world

populationPopulation

Population (2050)(estimated)

Illiteracy (% of adults)

Population under age 15 (%)

Population growth rate (%)

17%20%

1.1 billion1.3 billion

1.6 billion

IndiaChina

GDP PPP per capita

Percentage livingbelow $2 per day

Life expectancy

47%17%

36%20%

1.6%0.6%

1.4 billion

$5,890$3,120

4780

70 years62 years

2758

1.6 children per women (down from 5.7 in 1972)

Infant mortality rate

2.9 children per women (down from 5.3 in 1970)

Fig. 9-16, p. 188

Biologically simplified

Mostly nonrenewable fossil fuel energy

High

Often lost or wasted

Used, destroyed, or degraded to support human activities

Property

Complexity

Energy source

Waste production

Nutrients

Net primary productivity

NaturalSystems

Biologically diverse

Renewable solar energy

Little, if any

Recycled

Shared among many species

Human-Dominated Systems

Fig. 9-17, p. 188

Reduction of biodiversity

Increasing use of the earth's net primary productivity

Increasing genetic resistance of pest species and disease-causing bacteria

Elimination of many natural predators

Deliberate or accidental introduction of potentially harmful species into communities

Using some renewable resources faster than they can be replenished

Interfering with the earth's chemical cycling and energy flow processes

Relying mostly on polluting fossil fuels

Natural Capital Degradation

Altering Nature to Meet Our Needs

Human Population growth

• For most of our history a logistic curve.

• Currently exponential growth– Not uniform around the globe– Developing nations growing fastest

• What has made the change possible?– Drop in death rate. Birth rate has fallen, not

increased.

• How long will this be sustainable?

• Future predictions for growth?

Fig. 11.14, p. 246

Infant deaths per 1,000live births

<10

10-35

36-70

71-100

100+Data notavailable

Fig. 11.3, p. 240

<1%

1-1.9%

2-2.9%

3+%

Data notavailable

Annual worldpopulation growth

Fig. 11.4, p. 240

2.5

2.0

1.5

1.0

0.5

0.01950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

Gro

wth

rat

e (p

erce

nt)

Year

Fig. 11.5, p. 241

China

India

USA

Indonesia

Brazil

Pakistan

Russia

Bangladesh

Japan

Nigeria

2000 2025

1.26 billion1.4 billion

1 billion1.4 billion

276 million

338 million

212 million273 million

170 million

221 million

151 million

227 million

145 million137 million

128 million

177 million

127 million

121 million

123 million205 million

Fig. 11.6, p. 241

Asia

Europe

Africa

LatinAmerica

NorthAmerica

Oceania

3.7 billion

4.7 billion

728 million

714 million

800 million

1.3 billion

518 million

703 million

306 million

374 million

31 million

39 million

2000 2025

Fig. 11.10, p. 243

4.0

3.5

3.0

2.5

2.02.1

1.5

1.0

0.5

01920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Bir

ths

per

wo

man

Total fertility rates in USA 1917-2000

Baby Boom(1946-64)

Below replacement rate- immigration keeps population growing

Fig. 11.12a, p. 244

Extremely Effective

Total abstinence

Sterilization

Hormonal implant(Norplant)

100%

99.6%

98%

Highly Effective

IUD with slow-releasehormones

IUD plus spermicide

Vaginal pouch(“female condom”)

IUD

Condom (good brand)plus spermicide

Oral contraceptive

98%

98%

97%

95%

95%

93%

Birth Control Methods:

Effective

Cervical cap

Condom (good brand)

Diaphragmplus spermicide

Rhythm method (Billings,Sympto-Thermal)

Vaginal sponge impreg-nated with spermicide

Spermicide (foam)

89%

86%

84%

84%

83%

82%

Moderately Effective

Spermicide (creams,jellies, suppositories)

Rhythm method (dailytemperature readings)

Withdrawl

Condom (cheap brand)

Unreliable

Douche

Chance(no method)

75%

74%

74%

70%

40%

10%

Fig. 11.12b, p. 244

Fig. 11.13a, p. 245

Developed Countries

50

40

30

20

10

01775 1800 1850 1900 1950 2000 2050

Rat

e p

er 1

,000

peo

ple

Year

Rate ofnatural increase

Crudebirth rate

Crudedeath rate

Rate of natural increase = crude birth rate = crude death rate

Fig. 11.13b, p. 245

Developing Countries

50

40

30

20

10

01775 1800 1850 1900 1950 2000 2050

Rat

e p

er 1

,000

peo

ple

Crudebirth rate

Rate ofnaturalincrease

Crudedeath rate

Year

Fig. 11.15, p. 246

110

100

90

80

70

60

50

40

30

20

100

1930 1940 1950 1960 1970 1980 1990 20001920

Years

Dea

ths

un

der

ag

e 1

per

1,0

00 li

ve b

irth

s

Demographic transition

• Death rate ( infant mortality) drops first.• Birth rate remains constant• Population increase quickly• Economy transitions from agriculture to urban.• Larger families cost more, birth rate drops.• Population. Now much larger slows its growth

rate.• Influence of other (cultural, religious) pressures• Women often lack freedom to determine family

size, education employment opportunities

Fig. 9-14, p. 183

Birth rate

Death rate

Total population

Stage 1Preindustrial

Stage 2Transitional

Stage 3Industrial

Stage 4Postindustrial

Growth rate over time

Bir

th r

ate

and

dea

th r

ate

(nu

mb

er p

er 1

,00

per

yea

r)

Rel

ativ

e p

op

ula

tio

n s

ize

Low LowLow

Increasing Very high Decreasing Zero Negative

High

Fig. 9-6, p. 175

Demographic transition Depression

End of World War II

Baby boom Baby bust Echo baby boom

Bir

ths

pe

r th

ou

sa

nd

po

pu

lati

on

Year

Some predications

• Will technology save us? • The soft landing – no population

collapse

• Will we have a crash after we have exceeded our carrying capacity?

• No one knows

Fig. 11.9, p. 242

High

Medium

Low

12

11

10

9

8

7

6

5

4

3

21950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

High10.7

Medium8.9

Low7.3

Year

Po

pu

lati

on

(b

illio

n)

Fig. 11.22, p. 249

40

35

30

25

20

15

10

5

01950 1970 1990 2010 2030 2050 2070 2090 2110 2130 2150

Year

Ag

e D

istr

ibu

tio

n (

%)

Under age 15 Age 60 or over Age 80 or over

Fig. 11.24a, p. 251

Sta

te o

f th

e W

orl

d

1900 2000 2100

Year

Industrial output

Food

Resources

Population

Pollution

Fig. 11.25a, p. 254

Sta

te o

f th

e W

orl

d

1900 2000 2100

Year

Industrial output

Food

Resources

Population

Pollution

Influence on environment• More land fro agriculture, resource

exploitation• More land for cities, roadways, suburbs• Less fish in the sea for the food chain• Deforestation• Oil, gas won’t last forever• Pollution builds up• Better “green” technologies?• Heightened awareness, concern?• Better understanding of ecosystems?

Human disturbance

Tropic of Capricorn

Equator

Predominantly naturalPartially disturbedHuman dominated

AntarcticCircle

Tropic ofCancer

ArcticCircleArcticCircle

Fig. 1.4, p. 8

World total

Developingcountries

Developedcountries

Po

pu

lati

on

(b

illi

on

s)

12

11

10

9

8

7

6

5

4

3

2

1

1950 2000 2050 2100

YearFig. 1.6, p. 9

United States

The Netherlands

India

CountryPer Captia Ecological Footprint(Hectares of land per person)

10.9

5.9

1.0

Fig. 1.10a, p. 11