CHAPTER 52: POPULATION ECOLOGY
POPULATION DISPERSION PATTERNS
Population Growth Patterns
Type of Growth?
Exponential growth
“J curve”
Population Growth Patterns
Some populations of organisms reach a plateau in their growth.
This is called their carrying capacity.
These populations are said to be growing with logistical growth.
“S curve”
carrying
capacity
Carrying capacity – The number of organisms
that can be supported by a particular
ecosystem *within natural resource limitswithout destroying it.
*Limiting Factors…
Logistical vs. Exponential
Population Growth Patterns
1.
2.
3.
What is the carrying capacity of the
population on the right?
About how many days did it take for
the population to reach carrying
capacity?
Which of the following is probably
NOT a reason the population reached
and maintained a plateau?
a. limits in food supply
b. competition with other species
c. competition for space
d. a major storm
Logistical vs. Exponential
Population Growth Patterns
•
•
•
What is the carrying capacity of the
population on the right? around 135
individuals
About how many days did it take for the
population to reach carrying capacity?
about 80 days
Which of the following is probably NOT a
reason the population reached and
maintained a plateau?
a. limits in food supply
b. competition with other species
c. competition for space
d. a major storm would probably not cause a population to maintain its size
...THE MATH…
N = Population SIze
dN = Change in
Population Size
dt = Change in Time;
generation
r = 1.0 = BR – DR
(2-1 in this case)
1,500 = ?
*N small compared to
K- Max rate of
Increase
*N large/K limiting,
Rate of increase is
small (K-N/K is close
to zero)
N = Population SIze
dN = Change in
Population Size
dt = Change in Time;
generation
r = 1.0 = BR – DR
(2-1 in this case)
1,500 = ?
*N small compared to
K- Max rate of
Increase
*N large/K limiting,
Rate of increase is
small (K-N/K is close
to zero)
POPULATION
DYNAMICS

Birth rate/Death rate
United States 14.1/8.7
Australia 12.7/7.3
Iraq 34.2/6.0
Japan 10.0/8.5
Italy 8.9/10.1
Russia 9.7/13.9
Other Factors?




Migration:
Emigration,Immigration
Why?….for people…
Life Expectancy,Health
Care,Sanitation
Economics,Quality of
Life,Education
DENSITY DEPENDENT
VS
INDEPENDENT FACTORS
Density Dependent Factors: related to the
density of the population. (disease, predation,
competition)
 Density Independent Factors: Not related to
population size (killing frost, severe blizzard,
hurricane, etc)

Three Patterns of Population Growth
Causes?
CENSUS BUREAU



http://www.census.gov/population/international/data/
International Data
China

Single Birth Policy
When Instituted?
1978: SINGLE
BIRTH POLICY:
CHINA
In 1990?
R STRATEGISTS VS K STRATEGISTS

HW 52-9

Handout: Review of characteristics, curves
SURVIVORSHIP CURVES
SURVIVORSHIP CURVES
Matter and Energy in an Ecosystem
P/S:
Compare how
matter and energy
operate in
ecosystems?
(Are they
recycled)?
HW Ch54-2
ENERGY FLOW THROUGH ECOSYSTEMS

Text p1167
10% RULE
PYRAMID OF ENERGY:

Shows the energy available at each trophic level.
 The size of the blocks represents the
proportion of energy
 Measured in Joules or Calories
PYRAMID OF BIOMASS:
PYRAMID OF NUMBERS:
Illustration of the number of organisms at
each level

TROPHIC LEVELS
Usually 5 max
 Number of energy
steps from the sun
 Tropho =
nourishment

FOOD
KEYSTONE VS DOMINANT SPECIES

Definitions: ?

P/S: Humans: keystone or dominant species?
Dominant: Most abundant species in a community
Keystone: Species that has greater influence on community
structure than you would predict based on #’s. Maintains
species diversity (predation)





Grey Wolf
Fig Tree
?
HW Ch 53-10
DDT
1962
Persistence: Characteristics of certain chemicals
that are extremely stable and may take many
years to be broken down into simpler forms by a
natural process.
 Biological Accumulation: Buildup of a persistent
toxic substance such as pesticides, in an
organisms body.
 Biological Magnification:The increase in
concentration of a persistent toxin in the tissues
of organisms at higher trophic levels. HW54-7
