Population Parameters

• Natality: the birth rate of a population, normally expressed as the number of live births per thousand individuals per year
• Mortality: the death rate of a population, normally expressed as the number of deaths per thousand individuals per year
• Immigration: the one movement of organisms into an area where they become established
• Emigration: one way movement of organisms out of an area to become established
• Natality and immigration cause an increase in population size
• Mortality and emigration cause a decrease in population size
• A population where immigration and emigration do not occur, is known as a closed population
• The only parameters that affect the population size in a closed population are natality and mortality