Download Three Key Features of a Population

Population
Ecology
Population Dynamics
• Population:
• All the individuals of a species that live
together in an area
• Three Key Features of Populations
• Geographic distribution
• Density
• Growth Rate
Three Key Features of a Population
• Geographic Distribution: is the area inhabited by a
population of species.
• Example:
Three Key Features of Populations
Density: measurement of population per unit
area or unit volume
Three Key Features of Populations
• Growth Rate:
• Growth Rate depends on:
1. Immigration: movement of individuals into a
population
2. Emigration: movement of individuals out of a
population
3. Birth Rate:
4. Death Rate:
How do Populations Grow?
• Exponential Growth:
• Logistic Growth:
Factors Limiting Growth Rate
• Declining birth rate or increasing death rate are caused by
several limiting factors including:
• Competition:
• Parasitism and Disease:
• Predation:
• Drought and other climate extremes:
• Human Disturbances:
Density Dependent Vs. Density
Independent Factors
• Competition, predation, parasitism and disease
are density dependent factors.
- Density dependent factors become limiting only
when there are large and dense populations.
- Example:
• Human Disturbances, drought and climate
extremes are density independent factors.
- Density independent factors become limiting any
time they strike. They are independent of
population size.
- Example:
Classwork
• Can limiting factors such as shortage of food
cause mass extinctions of a species?
• Discuss how limiting factor(s) can contribute
to mass extinction? Use examples from the
article to support your answer.
History of the Human Population