Transcript Population Growth - Crestwood Local Schools

Population Growth
Chapter 5
Population
 Remember
a population is a group of
a particular species living in a
defined area
 Populations grow and they decline
Important Characteristics of a
Population
 Its
geographic distribution
– How far it is spread out
 Density
– The number of individuals per unit area
 Growth
rate
– How fast it is growing or declining
Factors That Affect a Population
Size
 The
number of births
 The number of deaths
 The number of individuals leaving or
entering the population
– Immigration- movement INTO an area
– Emigration- movement out of an area
Exponential Growth
If a population has abundant resources
and has no predators or diseases the
population will multiply and the population
will increase
 This can lead to Exponential Growthwhich occurs when individuals reproduce
at a constant rate
 If conditions are ideal growth will happen
exponentially

Exponential Growth
Logistic Growth
 When
resources are unlimited it
grows exponentially, however,
resources are limited so growth will
slow down after a certain point
 Logistic Growth- occurs when a
population’s growth slows or stops
Figure 5-4 Logistic Growth of Yeast Population
Section 5-1
Logistic Growth
Carrying capacity
Time (hours)
Carrying Capacity
 Carrying
Capacity- largest number of
individuals that an environment can
support
 The growth rate at this point is zero
Concept Map
Section 5-1
Population Growth
Population
Growth
can be
Logistic
growth
Exponential
growth
characterized by
No limits on
growth
Unlimited
resources
represented by
Constant
growth rate
J-shaped
curve
characterized by
Limits on
growth
which cause a
Falling
growth rate
represented by
S-shaped
curve
Limiting Factors
A
factor that causes population
growth to decrease
 Can be ….
– Density- Dependent
– Density- Independent
Density Dependent
 Competition
– When it becomes crowded they compete
for resources
 Predation
– When a predator population increases,
prey populations will decrease, and then
the predators will decrease and the prey
will increase
 Parasitism
& Disease
Density Independent
 Does
not depend on the size of the
population at all
 Unusual weather, natural disasters,
human activities, etc
Any Questions?
 “Information
democracy.”
is the currency of
--Ralph Nader
is an old saying that the
course of civilization is a race
between catastrophe and education.
In a democracy such as ours, we
must make sure that education wins
the race.”
--JFK
 “There