1. Ecology

2. Population Density The number of organisms per unit area
Dispersion: The pattern of spacing a population within an area
3 main types of dispersion
Clumped
Uniform
Random
The primary cause of dispersion is resource availability

3. Population growth rate
How fast a population grows
Factors that influence this are:
Birth rate
Mortality
Emigration
Immigration

4. Abiotic Limiting Factors
A limiting factor places an upper limit on the size of a population. Limiting factors can be biotic (for example, lack of food) or abiotic (for example, access to water).
Every species is able to survive within a range of abiotic factors such as temperature, light, and soil. This range is called the species’ tolerance range.
Abiotic Limiting factors include:
Temperature
Rain fall
Nutrients

5. Carrying Capacity Density Dependent Factors
the maximum, equilibrium number of organisms of a particular species th at can be supported indefinitely in a given environment. 
Abbreviation:  K
Density Independent Factors
Affect population regardless of size or distribution
Usually abiotic
Examples: drought, fire, flood…
Density Dependent Factors
Usually biotic
Examples: Predation, parasites, disease

6. Exponential Change Which would you choose?
Population Ecology: Population Growth Rate
Exponential Change
Which would you choose?
An employer offers you two equal jobs for one hour each day for fourteen days.
The first pays $10 an hour.
The second pays only 1 cent a day, but the rate doubles each day.
Which job will you accept?
Final payment
Ten dollar flat rate
Lag 6

7. Population growth models
Exponential growth model
J-curve
Grows slowly at first “lags”
After lag grows very fast! (exponentially)
Example: Bacterial growth

8. What population do you think this is?
Population Ecology: Population Growth Rate
What population do you think this is?

9. So, what do you think is going to happen to the human population?
We will probably reach our carrying capacity.
Our growth rate will start to look like most organisms, which is the Logistic Growth Model
Carrying Capacity (k)
What letter does this curve kind of look like?

10. S Curves Logistic Growth Model Often called the S-shaped growth curve
Population Ecology: Population Growth Models
S Curves
Logistic Growth Model
Often called the S-shaped growth curve
Occurs when a population’s growth slows or stops following exponential growth.
Growth stops at the population’s carrying capacity 10