1. Populations

2. Essential Questions What factors influence changes in populations?
How do species interact with one another?

3. Population
All of the members of the same species living in the same area.
Inbreeding
Isolation

4. Population Density The number of individuals per area
Usually per square mile
Washington, CT – 96 people/sq. mi.
Shelton, CT – 1,294
Manhatten – 71,201 people/sq. mi.

5. Population Dispersion
How individuals are distributed within their range
Even
Clumped
Random

6. Growth Rate Birth Rate – Death Rate
What factors affect birth and death rates?

7. Reproductive Potential
The maximum number of offspring that an individual can produce.
Elephants: 19 mm offspring in 750 years
Bacteria: 19 mm offspring within days

8. Reproductive Potential
What factors affect reproductive potential?
How early reproduction begins
* most important factor
How often can individual reproduce
How many individuals can be produced

9. Reproductive Potential
elephants: 1 offspring every two years
sexual maturity 9-12 years
house mouse: litters of 10 or more 10 times a year
sexual maturity within 5 weeks

10. Generation Time
The length of time required for an individual to reach sexual maturity
shorter generation time = greater reproductive potential

11. Exponential Growth
Rapid growth in which population increases by certain factors with each generation
No limiting factors:
food, space
competition
predators

12. Limits to population growth

13. Carrying Capacity The maximum population an ecosystem can support
Carrying capacity hard to determine ecosystems change many factors
average populations

14. Limits on Resources
Carrying capacity reached when resources are used up at same rate as they are replaced.

15. Limiting Resource
Resource that determines the carrying capacity of a species.

16. Competition Within species Territoriality
social response to limit competition
with other species
invasive species

17. Density and Population Regulation

18. Density Dependant Degree of regulating effect depends on density.
limiting factors, predation, and disease
reproduction

19. Density Independent
Degree of regulating effect not dependant on density
natural disasters, weather, climate shift