1. EQ: How do we measure populations?
Population Ecology
EQ: How do we measure populations?

2. Population Dynamics Population:
All the individuals of a species that live together in an area
Demography:
The statistical study of populations, allows predictions to be made about how a population will change
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

3. Three Key Features of Populations: Size
Size: number of individuals in an area
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

4. Three Key Features of Populations: Size
Growth Rate:
Birth Rate (natality) - Death Rate (mortality)
How many individuals are born vs. how many die
Birth rate (b) − death rate (d) = rate of natural increase (r)
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

6. Three Key Features of Populations: Density
Density: measurement of population per unit area or unit volume
Pop. Density = # of individuals ÷ unit of space
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

7. How Do You Affect Density?
Immigration: movement of individuals into a population
Into
Emigration: movement of individuals out of a population
Exits
Density-dependent factors: Biotic factors in the environment that have an increasing effect as population size increases (disease, competition, parasites)
Density-independent factors: Abiotic factors in the environment that affect populations regardless of their density (temperature, weather)

8. Factors That Affect Future Population Growth
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Factors That Affect Future Population Growth
Immigration + + -
Population
Mortality
Natality -
Emigration

9. Three Key Features of Populations: Dispersion
Dispersion: describes the spacing of organisms relative to each other
Clumped
Uniform
Random
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

10. Population Dispersion

11. How Are Populations Measured?
Count all the individuals in a population
Estimate by sampling
Mark-Recapture Method

12. How Do Populations Grow?
Exponential Growth – when individuals in a population reproduce at a constant rate
Under ideal conditions with unlimited resources, a population will grow exponentially

13. How Do Populations Grow?
Logistic Growth – when a population’s growth rate slows or stops flowing a period of exponential growth
- Happens when resources become less available

14. Carrying Capacity (k):
The maximum population size that can be supported by the available resources
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

15. Factors Limiting Growth Rate
Declining birth rate or increasing death rate are caused by several factors including:
Limited food supply
The buildup of toxic wastes
Increased disease
Predation

16. “Booms” and “Busts”

17. History of the Human Population

18. Human Population Growth
Grows at a rate of about 80 million yearly
Why doesn’t environmental resistance take effect?
Altering their environment
Technological advances
The cultural revolution
The agricultural revolution
The industrial-medical revolution