1. Population Biology

2. Levels of Organization
Ecological organization:
Species
Population
Community
Ecosystem
Biome
Biosphere

3. Species
Group of similar organisms that can breed and produce fertile offspring

4. Population
group of organisms, all of the same species, which interbreed and live in the same area.

5. Community
groups of different populations that live together

6. Ecosystem
Collection of organisms that live in a place with the nonliving environment

7. Group of ecosystems with the same climate and vegetation
Biome
Group of ecosystems with the same climate and vegetation
Tropical rain forest
Tropical dry forest
Tropical savanna
Temperate woodland
and shrubland
Desert
Temperate grassland
Boreal forest
(Taiga)
Northwestern
coniferous forest
Temperate forest
Mountains and
ice caps
Tundra
Ecosystem

8. Biosphere
The part of the earth where life exists including land, water, air, and atmosphere

9. Population We’re going to Study the population level
What is a Population?

10. Density and Distribution of Populations
Population Density - Number of individuals per unit area or volume.
Population Distribution - Pattern of dispersal of individuals within the area of interest.

11. Population Density or Population Distribution?

12. Population Distributions
Random
Uniform
Clumped

13. Uniform Distribution
EXAMPLE

14. Random Distribution
EXAMPLE

15. Clumped Distribution
EXAMPLE

16. What controls population?

17. Factors affecting biotic potential
Birth potential: max # of offspring per birth
eg. Dog-5 human-1 Fruit fly – many
Capacity for survival: the # of offspring that reach a reproductive age
eg. Humans Cats – 1
Procreation: the # of times that species reproduces per year
eg. Human - 1 fruit fly- every few days!
Length of reproductive life: the # of years that an organism can reproduce
eg. Salmon- only once
Elephant- 22 month gestational period
Humans- 9 months
Whale- 11 months

18. What controls population?
2. Limiting Factors:
Environmental factors that prevent an organism from reaching its biotic potential.
2 types
Density dependent
Density independent

19. There are 2 main categories of limiting factors:
1. Density-dependent factors- factor that depend on the size of the population to act
Density-independent factors- affect all populations equally, regardless of population size

20. Density dependent Factors
Density-dependent limiting factors include:
competition
predation
parasitism
Disease
These factors exist when a population is large and dense.
They do not affect small, scattered populations as greatly.

21. Parasitism Organisms that live and feed on other organisms
The host is the organism that the parasites live on.
parasites don’t kill the host but may weaken causing death

22. Predator/Prey One organism kills and eats another organism.
Prey is being eaten - predator does the eating.

23. Competition
Two or more organism of the same or different species use the same limited resources.

24. Density Independent Factors
Density Independent Include natural phenomena, such as weather events
unusual weather
natural disasters
seasonal cycles
certain human activities—such as damming rivers and clear-cutting forests

25. Carrying Capacity Carrying Capacity:
The largest population of a species that can be sustained in an ecosystem over time

26. Our Future?

27. Population Graphing Worksheet

28. Exponential Growth in a population
J-curve
Occurs when a population starts out small and
no limitations on resources.

29. Bacterial Growth
Eventually the bacteria will grow until a factor limits growth
Amazingly these are called limiting factors!!

30. S Growth Curve Key phases Slow Growth Rapid growth Steady State
Occurs when there are limiting factors on a population and the carrying capacity is reached
Bacteria Growth
Key phases
Slow Growth
Rapid growth
Steady State
Decline or death phase

33. Exponential vs S Curve