1. Populations Objectives:
Identify factors that contribute to population growth
Describe exponential and logistic growth
Compare and contrast density-dependent and density-independent limiting factors

2. All the members of a species located in the same area
I. Population:
All the members of a species located in the same area

3. II. Characteristics of Populations
A. Density
B. Dispersion
1. Uniform/ Regular
2. Clumped/ Aggregated **
3. Random

4. III. Population Growth A. Growth rate determined by:
1. Births – Deaths
2. In a local population, also determined by:
Immigration – Emigration
B. Fastest rate a population can grow = Biotic Potential
Limited by reproductive potential
High for organisms that reproduce quickly, don’t care for young (Ex. Insects)
Lower for organisms that have few offspring at once, care for young (Ex. Humans)

5. Population Growth…
C. If conditions are favorable, populations continue to increase in size

6. III. Exponential Growth
A. Population grows faster and faster
B. Represented by J-curve

7. C. As population continues to increase, so does population density
D. Needed materials begin to run out: Competition (think “survival of the fittest”):
1. Interspecific – between different species
2. Intraspecific - among members of the same species
E. No population can continue to increase indefinitely
Every environment has a carrying capacity

8. IV. Limiting Factors A. Keep a population from growing
1. Density-dependent: competition for resources, disease
2. Density-independent: natural disaster
B. Can cause population decrease due to death or migration
C. Lead to competition and natural selection

9. V. Logistic Growth
A. As population approaches carrying capacity, growth rate slows
1. Births decrease
2. Deaths increase
B. S-curve emerges
C. Limiting factors

10. Can a population overshoot its carrying capacity?

12. Analyzing population data…
content/crash-course1/cc-ecology/v/crash-course- ecology-02