r & K Selection

Climate r-selected species live in variable or unpredictable environments K-selected species live in fairly constant or predictable environment

Mortality, Survivorship, & Competition In r-selected species mortality is often catastrophic and subject to density independent limiting factors. Survivorship is low early in life but increases for those individuals surviving (Type III). Competition lax. In K-selected species mortality is subject to density dependent limiting factors Survivorship is high throughout life until late in life (Type I). Competition keen.

Population Size In r-selected species, population size tends to vary in time and recolonization occur into unpopulated area frequently (pioneer species) In K-selected species, population size is usually at or near the carrying capacity and colonization is infrequent (keystone species in climax communities)

r Species Selection Factors Rapid Development High r = or net reproductive rate Early Reproduction Small Body Size Single Reproduction Many Small Offspring Short Life Span

K Species Selection Factors Slow Development Competitive Ability Delayed Reproduction Large Body Size Repeated Reproduction Few Large Offspring Long Life Span