copyright © 2005 pearson prentice hall, inc. chapter 39 population growth and regulation

Copyright © 2005 Pearson Prentice Hall, Inc.

Chapter 39

• Population Growth and Regulation


How Does Population Size Change?

• Biotic Potential Can Produce Exponential Growth– Exponential growth curves are J-shaped (F39.1 p.

800) – The effect of death rates on population growth

(F39.2 p. 801)

number of individuals time (minutes)

time (years)

Reproduction begins at 6 years

bacteria

eagles(i)

(ii)

time number of (minutes) bacteria

0 120 240 460 880 16

100 32120 64140 128160 256180 512200 1024220 2048

time number of number of(years) eagles (i) eagles (ii)

0 2 22 2 24 4 26 8 48 14 8

10 28 1212 52 1614 100 3216 190 5418 362 8620 630 14222 1314 23824 2504 39226 4770 64428 9088 106630 17314 1764

number of individuals

time (minutes)

bacteria

time number of (minutes) bacteria

0 120 240 460 880 16

100 32120 64140 128160 256180 512200 1024220 2048


time (years)

Reproduction begins at 6 years

time number of number of(years) eagles (i) eagles (ii)

0 2 22 2 24 4 26 8 48 14 8

10 28 1212 52 1614 100 3216 190 5418 362 8620 630 14222 1314 23824 2504 39226 4770 64428 9088 106630 17314 1764

(i)

(ii)

no deaths


time (hours)

bacteria

10% die between doublings

25% die between doublings


How Is Population Growth Regulated?

• Exponential Growth Cannot Continue Indefinitely– A boom-and-bust population cycle (F39.3 p. 801) – Lemming population cycles follow a boom-

and-bust pattern (F39.4 p. 801)

population density

approximate number of lemmings per acre



• Environmental Resistance Limits Population Growth– The S-curve of population growth (F39.5 p. 803)

– The effects of exceeding carrying capacity (F39.6

p. 804)

carrying capacity

time

exponentialgrowth: J-curve

(environmental resistance)

equilibrium(bioticpotential)

num

ber

of i n

divi

dua l

s

exponentialgrowth

populationcrash

year

num

ber

of r

eind

eer

0

500

1000

1500

2000

1910 1920 1930 19501940



– Density-Independent Factors Limit Populations Regardless of Their Density

– Density-Dependent Factors Become More Effective as Population Density Increases

– Predators and Parasites Exert Density-Dependent Controls on Populations

• Predators help control prey populations (F39.7 p. 805)



– Competition for Resources Helps Control Populations

• Emigration (F39.8 p. 806)



• Survivorship in Populations Follows Three Basic Patterns– Survivorship curves (F39.9 p. 807)

1000

100

10

0

num

ber

of s

urvi

vors

age(in percentage of maximum life span)

early loss(dandelion)

constant loss(American robin)

late loss(human)


How Is the Human Population Changing?

• The Human Population Is Growing Rapidly– Human population growth (F39.10 p. 808)

Technical and cultural advances Agricultural advances Industrial andmedicaladvances

bubo

nic

plag

ue

bil li

ons

of p

eopl

e

7

6

5

4

3

2

1

0

20031999

1987

1975

1960

1930

1830

12,000 11,000 10,000 9000 8000 7000 6000 5000 4000 3000 2000 1000 B.C./A.D. 1000 2000 B.C. B.C. B.C. B.C. B.C. B.C. B.C. B.C. B.C. B.C. B.C. B.C. A.D. A.D.



• Technological Advances Have Increased Earth’s Carrying Capacity for Humans– Unnumbered Figure 1 (p. 809) – Unnumbered Figure 2 (p. 809)

time

death rate

naturalincrease

birth rate

Demographic transition

birt

h an

d de

ath

rate

2003: 6.3 billion

developing countries

developed countries

10

8

6

4

2

0

po

pu

latio

n (

bill

ion

s)

1950 1970 1990 2010 2030 2050



• The Age Structure of a Population Predicts Its Future Growth (F 3 p. 810) – Age structures compared (F39.11 p. 810) – Population change by world regions (F39.12 p.

811)

expanding stable shrinking

postreproductive(46–100 years)

reproductive(15–45 years)prereproductive(0–14 years)

Developed countries 2003 2025

postreproductive (45–79 yr)

reproductive (15–44 yr)

prereproductive (0–14 yr)

millions of people

millions of people

age

age

Developing countries

(a)

(b)

80

70

60

50

40

30

20

10

0

80

70

60

50

40

30

20

10

0

320 280 240 200 160 120 80 40 0 40 80 120 160 200 240 280 320

320 280 240 200 160 120 80 40 0 40 80 120 160 200 240 280 320

World average 1.3%

Developing countries 1.6%

World regions

annual natural increase

Africa 2.4%

Latin America/Caribbean 1.7%

Asia (excluding China and Japan) 1.6%

Developed countries 0.1%

China 0.6%

N. America 0.5%

Europe –0.2%



• The United States Population Is Growing Rapidly– U.S. population growth (F39.13 p. 812)

– Population cycles in predators and prey (FE39.1 p. 802) – Experimental predator–prey cycles (F E39.2 p. 802)

– Deforestation can lead to the loss of productive land (FE39.3 p. 813)

U.S. population (in millions)(1790–2003)

year

abundance of lynx ( 1000)

abundance of hares ( 1000)

year

hares (prey)lynx (predator)

adult population

generation

bean weevils (prey)

branconid wasp (predator)

copyright © 2005 pearson prentice hall, inc. chapter 39 population growth and regulation

Documents

population density slide

population growth f39

exponential growth population

regulation slide

years timenumber of

pearson prentice hall

bust population cycle

lemming population cycles