1. Population Dynamics Class Notes

2. 3 Population Characteristics
Population density – number of organisms per unit area

3. 3 Population Characteristics
2. Spatial distribution – based on dispersion, which is the spacing pattern of a population within a certain area.
a. Uniform
b. Clumped
c. Random
What do the 3 distribution types look like?

4. 3 Population Characteristics
3. Population Ranges – organisms are able to live only in certain habitats
Ex:The iiwi only lives
on the Hawaiian islands.

5. Population-Limiting Factors
Density-independent factors – any factor that does not depend on the density of a population
Typically abiotic
Natural weather events – tornado, tsunami, drought
Results of human activities – pollution

6. Population-Limiting Factors
2. Density-dependent factors – any factor that depends on the population density
Typically biotic
Disease – spreads easily in dense populations
Competition – limited resources
Parasites-parasites spread like disease

7. Review
The Black Death killed 75 million people at the beginning of the 20th century. Which size was the population most likely at that time?
a. Small population, spread out
b. Small population, close together
c. Large population, spread out
d. Large population, close together

8. Review
2. Which of the following is an example of a density-independent factor? More than one is correct.
a. Flood
b. Parasites
c. Deforestation
d. Competition
A and C

9. Population Growth Rate
To compute how fast a population is growing, these must be known:
Birth rate
Death rate
Immigration: when organisms come into a population
Emigration: when organisms exit a population

10. Models for Population Growth
Exponential Growth Model – population growth with no environmental limits
Unlimited resources – food, space, mates

11. Exponential Growth Lag phase – slow growth period
J-shaped curve – exponential growth
J-curve
Lag phase

12. Models for Population Growth
2. Logistic Growth Model – population growth slows,
birth rate is less than death rate
S-shaped curve
Carrying capacity
Lag
phase

13. Logistic Growth
Carrying capacity – the maximum number of organisms an environment can support long-term
C.C.is limited by the resources available.
This model explains why and how populations stabilize.

14. Review 3. What is emigration?
When organisms exit or leave a population

15. Review
4. Which model – exponential or logistic – is more realistic for a population?
Logistic – typically resources are limited in an environment

16. R-strategists Characteristics of R-strategists: Small organisms
Short lifespan
Produce many offspring
Expend little energy to raise offspring

17. R-strategists Examples

18. K-Strategist Characteristics of K-strategists: Larger organisms
Longer life span
Produces few offspring
Time is invested in care of young

19. K-Strategist Examples