The Growth of Populations
Population growth: balance of birthrate, deathrate, emigration, and immigration: r = (b - d) + (i - e)
Exponential growth: 2 make 4, 4 make 8, 8 make 16, … rN = dN/dt; N increases exponentially NOTE: growth rate r remains constant! exponential growth only possible if resources are unlimited; in nature, resources are always finite.
Carrying capacity: maximum N for given level of resources
Logistic growth: growth curve is sigmoidal because growth rate r decreases when N approaches carrying capacity K