1. Populations
Lesson 2

2. Population
all of the members of a species living in the same ecosystem or habitat.

3. Population growth patterns
Changes in population size occur when individuals are added to or removed from a population.
Natality (birthrate) and Immigration (movement into an area) increase a population.
Mortality (death rate) and emigration (movement out of an area) decrease a population.

4. Population growth patterns
These four factors interact to determine population size
Population growth = births + immigration – deaths – emigration

5. Open and Closed Populations
Open populations = populations where births, immigration, death and emigration all act on the population of an organism.
Closed population = populations where only births and deaths affect their population size. These are normally only found on islands, game reserves and labs.

6. Limits on Populations
Biotic Potential – the maximum number of offspring that a species could produce if resources were unlimited. Regulated by 4 important factors
Birth potential - maximum number of offspring per birth
Capacity for survival – the number of offspring that reach reproductive age
Procreation – The number of times that a species reproduces in a year
Length of reproductive life. – The age of sexual maturity and the number of years the individual can reproduce.

7. Limits on Populations
Limiting Factors – Any resource that is in short supply is a limiting factor on a population. Food, water, territory, and the presence of pollutants.
Carrying Capacity – The maximum number of individual of a species that can be supported indefinitely by the ecosystem.

8. Case Study