Transcript ch 4 population ecology student

Chapter 4: Population Ecology
Essential Questions:
•Investigate the
relationships among
organisms,
populations,
communities,
ecosystems, and
biomes.
• EQ: How would changes in
populations affect the flow
of energy and matter in
the ecosystem?
• EQ: How are populations
regulated over time?
• EQ: How does the growing
human population
threaten the biosphere?
Chapter 4 Population Ecology
Section 1: Population Dynamics
Section 2: Human Population
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• A laboratory jar containing a population of
beetle larvae (mealworms) has reached a
stable population size. We decide to add
twice as much food per day to the jar, but
this turns out to have no effect on population
size.
• What is the most likely explanation?
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Populations
• Defined by different
• __________________
__________________
• appropriate to the
questions being asked
• Important characteristics:
–
–
–
–
–
_______________
_______________
_______________
_______________
_______________
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What is POPULATION DENSITY?
• The number of individuals
of a species per unit area or
volume.
• Three factors can affect
population size
– number of____________
– number of _____________
– number of individuals that
______________________
__________ the population
• __________________
(im-uh-gray-shun), the
movement of individuals
into an area, is another
factor that can cause a
population to grow.
• __________________
(em-uh-gray-shun), the
movement of individuals
out of a population, can
cause a population to
decrease in size.
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Chapter 4
Population Ecology
4.1 Population Dynamics
_______________________
 The number of organisms per unit area
Spatial Distribution
 _________________is the pattern of
spacing of a population.
Chapter 4
Population Ecology
4.1 Population Dynamics
________________________
 A species might not be
able to expand its
population range because
it cannot survive the
abiotic conditions found in
the expanded region.
Common dolphin
Pupfish
EQ:
How are populations regulated
over time?
Population Limiting Factors
• Environmental factors that restrict population
growth.
• Some limiting factors depend on the size of the
population.
• Other limiting factors affect all populations in similar
ways, regardless of the population size.
Warm-up: Population Limiting Factors
1. Imagine a small island that has a population of five rabbits.
How might each of the following factors affect the rabbit
population?
a. climate
b. food supply
c. predation
2. Now imagine another small island that has a population of
500 rabbits. How would the same factors affect this
population?
3. Which of the factors depend on population size? Which
factors do not depend on population size?
Chapter 4
Population Ecology
4.1 Population Dynamics
Population-Limiting Factors
 There are two categories of limiting
factors__________________________factors
and_______________________________.
Chapter 4
Population Ecology
4.1 Population Dynamics
Density-Dependent Factors
 Any factor in the environment that depends
on the number of members in a population
per unit area is a______________________.
 Biotic factors
 Disease
 Competition
 Parasites
Population
Biology
A Density-Dependent Limiting Factor
Section 5-2
Growth of Aphids
Exponential growth
Peak population
size
Rapid decline
Steady population
size
Steady population
size
Chapter 4
Population Ecology
4.1 Population Dynamics
Density-Independent Factors
 Any factor in the environment that does
not depend on the number of members
in a population per unit area is
________________.
 _________________
 _________________
 ______________________________
 ______________________________
Checkpoint!
1. Name 2 types of limiting factors for a population.
2. Of the following factors with the potential to limit
growth of a human population, which one is most
density-independent?
– Mass drowning caused by hurricane flood
– Freezing deaths due to a shortage of housing
Chapter 4
Population Ecology
4.1 Population Dynamics
Population Growth Rate
 The _________________________(PGR)
explains how fast a given population grows.
 The natality of a population is the birthrate
in a given time period.
Chapter 4
Population Ecology
4.1 Population Dynamics
Exponential Growth Model
 Exponential growth
occurs when the
growth rate is
_______________to
the size of the
population.
 All populations grow
_______________unt
ilsome ____________________slows the
population’s
growth.
Chapter 4
Population Ecology
4.1 Population Dynamics
Logistic Growth Model
 The population’s
growth
___________or
___________followi
ng exponential
growth, at the
population’s_______
_______________
Chapter 4
Population Ecology
4.1 Population Dynamics
A population stops increasing
when the number of births is
________than the number of deaths
when emigration
______________immigration.
Chapter 4
Population Ecology
Chapter 4
Population Ecology
4.1 Population Dynamics
Carrying Capacity
 The _____________number of individuals in
a species that an ____________________for
the long term is the carrying capacity.
 Carrying capacity is limited by
the___________,___________,__________,
and _____________available.
Concept Map
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
Checkpoint!!!
• Which of the following is NOT a condition
for a population to reach exponential
growth?
– presence of unlimited resources
– absence of predation and disease
– movement of individuals out of a population
Chapter 4
Population Ecology
4.1 Population Dynamics
Reproductive Patterns
 Species of organisms vary
in the number of _____________per
reproduction_________
in the __________that reproduction begins
in the _______________of the organism.
Chapter 4
Population Ecology
4.1 Population Dynamics
 The rate strategy, or r-strategy, is an
adaptation for living in an environment where
fluctuation in biotic or abiotic factors occur.
 An r-strategist is generally a_______________.
 ____________life span
 Produces ____________offspring
Chapter 4
Population Ecology
4.1 Population Dynamics
 The carrying-capacity strategy, or kstrategy, is an adaptation for living in stable
environments.
 A k-strategist is generally a ________organism.
 _______________life span
 Produces____________ offspring
Chapter 4
Population Ecology
4.2 Human Population
Human Population Growth
 The study of human population size, density,
distribution, movement, and birth and death rates is
demography.
Chapter 4
Population Ecology
4.2 Human Population
Technological Advances
 For thousands of years, environmental
conditions kept the size of the human
population at a relatively constant number
below the environment’s carrying capacity.
 Humans have learned to alter the
environment in ways that appear to have
changed its carrying capacity.
Chapter 4
Population Ecology
4.2 Human Population
Human Population
Growth Rate
 Although the
human population
is still growing, the
rate of its growth
has slowed.
Chapter 4
Population Ecology
4.2 Human Population
Trends in Human Population Growth
 Population
trends can
be altered by
events such
as disease
and war.
 Human
population
growth is not the same in all countries.
Chapter 4
Population Ecology
4.2 Human Population
Zero Population Growth
 Zero population growth (ZPG) occurs when
the birthrate equals the death rate.
 The age structure eventually should be more
balanced with numbers at pre-reproductive,
reproductive, and post-reproductive ages
being approximately equal.
Chapter 4
Population Ecology
4.2 Human Population
Age Structure
 A population’s
age structure
is the number
of males and
females in
each of three
age groups:
pre-reproductive stage, reproductive stage, and postreproductive stage.
Chapter 4
Population Ecology
4.2 Human Population
Human Carrying Capacity
 Scientists are
concerned about the
human population
reaching or exceeding
the carrying capacity.
 An important factor is the
amount of resources from
the biosphere that are
used by each person.
Check it?
1. Name 2 types of limiting factors for a population.
2. Of the following factors with the potential to limit
growth of a human population, which one is most
density-independent?
– Mass drowning caused by hurricane flood
– Freezing deaths due to a shortage of housing
Check it?
3. Which of the following is NOT a
condition for a population to reach
exponential growth?
– presence of unlimited resources
– absence of predation and disease
– movement of individuals out of a population