Population Dynamics Section 4.1, p.92 3/19/2016

Population Dispersion -How individuals are spaced within an area

Population Density Number of organisms per unit area Number of organisms per unit area

Population Limiting Factors Density-dependent Density-dependent Deaths occur more quickly in a crowded populationDeaths occur more quickly in a crowded population Ex: resources, predation, diseaseEx: resources, predation, disease Density-independent Density-independent A certain proportion dies regardless of population densityA certain proportion dies regardless of population density Ex: severe weather, natural disasterEx: severe weather, natural disaster

Predation – what happened to the moose population as the wolf population increased?

Population Growth Rate How fast a given population grows How fast a given population grows Most look at birth rate and death rate Most look at birth rate and death rate

Factors Affecting Growth Rate of a Population Natality – number of births Natality – number of births Mortality – number of deaths Mortality – number of deaths E migration – leaving or exiting a population E migration – leaving or exiting a population I mmigration – moving into a population I mmigration – moving into a population

Carrying Capacity Max # of individuals of any species that can be supported by a particular ecosystem on a long-term basis Max # of individuals of any species that can be supported by a particular ecosystem on a long-term basis Change in ecosystem-change in carrying capacity Change in ecosystem-change in carrying capacity

Exponential Growth Growth at a constant rate of increase per unit of time Growth at a constant rate of increase per unit of time Example: 2,4,8,16,32,64,128 Example: 2,4,8,16,32,64,128 “J curve” “J curve”

Logistic Growth Exponential growth until carrying capacity is reached Exponential growth until carrying capacity is reached Growth then slows or stops Growth then slows or stops “S” curve “S” curve