populations. overview population: all the individuals of one species in a given area how populations...
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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