Factors that Influence Population Size
Size
Density
Distribution
Immigration
Emigration
decrease population size
increase population size
number of individuals in a given area
location of individuals relative to one another
Limits on Population Growth
Density-Dependent Factors
Density-Independent Factors
causes birth rate to slow and death rates to rise
predation, parasitism, disease, and competition
Logistic growth
occurs when density-dependent factors affect population size over time
natural disasters or weather-related events affect population size
K selection
occurs when a population is near its environment's carrying capacity
R selection
occurs when population density is low and resources are abundant
arrival of new residents that previously belonged to another population
the departure of individuals who take up permanent residence elsewhere