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Population Dynamics Section 4.1, p.92 5/22/2017 Population Dispersion -How individuals are spaced within an area Population Density Number of organisms per unit area Population Limiting Factors Density-dependent • Deaths occur more quickly in a crowded population • Ex: resources, predation, disease Density-independent • A certain proportion dies regardless of population density • Ex: 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 Most look at birth rate and death rate Factors Affecting Growth Rate of a Population Natality – number of births Mortality – number of deaths Emigration – leaving or exiting a population I mmigration – moving population into a Carrying Capacity 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 Exponential Growth Growth at a constant rate of increase per unit of time Example: 2,4,8,16,32,64,128 “J curve” Logistic Growth Exponential growth until carrying capacity is reached Growth then slows or stops “S” curve