1. Georgia Performance Standards:
Chapter 4: Populations
Georgia Performance Standards:
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?

2. Warm-up:
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?

3. Populations Important characteristics:
Defined by different geographical boundaries
Important characteristics:
Density
Geographical Distribution
Growth Rate
Age Structure

4. What is POPULATION DENSITY?
Immigration (im-uh-gray-shun), the movement of individuals into an area, can cause a population to grow.
Emigration (em-uh-gray-shun), the movement of individuals out of a population, can cause a population to decrease in size.
The number of individuals of a species per unit area or volume.
Three factors can affect population size
# of births
# of deaths
# of individuals that enter or leave the population

5. How do populations grow?
Exponential Growth
Under ideal conditions with unlimited resources, a population will grow exponentially
The whole population multiplies by a constant factor during constant time intervals
Organisms do not usually grow exponentially for very long.

6. Exponential Growth
Both of these hypothetical graphs show the characteristic J-shape of exponential population growth.

7. Logistic Growth S-shaped curve of this growth pattern
 As resources become less available, the growth of a population slows or stops= Logistic growth
Can follow a period of exponential growth
S-shaped curve of this growth pattern
birthrate=deathrate immigration =emigration

8. Logistic Growth of Yeast Population
Carrying Capacity
Number of yeast cells
Time (hours)

9. Carrying Capacity
The number of individuals in a population that the environment can just maintain with no net increase or decrease

10. Concept Map Population Growth Logistic Exponential growth Limits on
can be
Exponential
growth
Logistic
characterized by
represented by
characterized by
represented by
Falling
growth rate
S-shaped
curve
Limits on
growth
No limits on
J-shaped
Constant
Unlimited
resources
which cause a

11. 5–1 Summary: How Populations Grow
Three important characteristics of a population are:
geographic distribution
density
growth rate.
Three factors affect population size: # of births
# deaths,
# of individuals that enter or leave the population.
Under ideal conditions and unlimited resources, a population will continue to grow in a pattern called exponential growth. As resources are used up and population growth slows or stops, the population exhibits logistic growth.
Vocabulary
population density
immigration
emigration
exponential growth
logistic growth
carrying capacity

12. 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

13. EQ: How are populations regulated over time?

14. 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.

15. 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?

17. Density-dependent Factors
Factors that depend on the population density
Factors affect a greater percentage of individuals in a population as the number of individuals increases.
Death rate increases and the birth rate decreases
Limited food supply
Competition
Predation
Parasitism
Disease
Buildup of poisonous wastes

18. Density-independent Factors
Limiting factors whose occurrence is not affected by population density
Abiotic factors; climate and weather or natural disasters and human activity
Affect the same percentage of individuals regardless of the population size.
Abiotic factors
climate and weather
natural disasters
human activity
Damming rivers
Clear-cutting forests

19. 5–2 Summary: Limits to Growth
Vocabulary
limiting factor
density-dependent limiting factor
predator-prey relationship
density-independent limiting factor
Density-dependent limiting factors include competition, predation, parasitism, and disease.
Unusual weather, natural disasters, seasonal cycles, and certain human activities—such as damming rivers and clear-cutting forests—are all examples of density-independent limiting factors.

20. EQ: How does the growing human population threaten the biosphere?
The Human Population
EQ: How does the growing human population threaten the biosphere?

21. The size of the human population tends to increase with time

22. Demography The scientific study of human populations
Birth rates
Death rates
Age structure of population
All help to predict why some countries have high growth rates while other countries grow more slowly.

23. Demographic Transition
A dramatic change in birth and death rates
The demographic transition is complete when the birthrate falls to meet the death rate, and population growth stops.
Birthrates and death rates fall during the demographic transition. Initially, both rates are high (A). Then, the death rate drops while the birthrate remains high (B). Finally, the birth rate also decreases (C).

24. Age-structure diagrams
A population profile that can predict future growth.
Shows the number of people in different age groups in the population

26. Human Activities Section 6-1 Hunting and gathering Agriculture
that have changed the biosphere include
Hunting and
gathering
Agriculture
Industrial
growth
Urban
development
may have once caused
often relies on the methods of the
have resulted in
Extinctions of
large animals
Green
revolution
High standard
of living
Increased
pollution
which increased
Food supply
Pesticide use
Monoculture
use
Go to Section:

27. Threats to Biodiversity
Human activity can reduce biodiversity by altering habitats (Habitat fragmentation), hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species (Invasive species) to new environments.
Extinction occurs when a species disappears from all or part of its range.
A species whose population size is declining in a way that places it in danger of extinction is called an endangered species.
As the population of an endangered species declines, the species loses genetic diversity
Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.

28. 5–3 Summary: Human Population Growth
Like the populations of many other living organisms, the size of the human population tends to increase with time.
The characteristics of populations, and the social and economic factors that affect them, explain why some countries have high population growth rates while populations of other countries grow slowly or not at all.
Vocabulary
demography
demographic transition
age-structure diagram