C3-C4: Factors that Inhibit Growth: Density Dependant and Density Independent Factors

C4. Life Strategies Two factors govern the type of population growth a particular species will exhibit:

Examples of Density Dependant factors that limit growth:

• Disease

• Competition

• Available resources

• Predation

Examples of Density Independent factors that limit growth:

• Weather (climate change)

• Nutrient Availability

Biotic Potential (r):

The maximum reproductive potentials of an organism which is influenced by

• #of offspring per birthing event

• # of birthing events

• Age of sexual maturity

• # of reproductive events over a lifetime

Carrying Capacity (k):

The maximum number of organisms an environment can support. often populations will “overshoot” their carrying capacity and then have a correction as the population drops back down.

r-Strategists

• High biotic potential

• J-shaped growth curve

• Lives in rapidly changing environements

• Short life span

• Variable population size

• Density independent mortality

• Single reproductive event at a young age

• Little or no parental care

• Large # of offspring

• EX. Insects

k-Strategists

• Lower biotic potential

• S- Shaped growth curve

• Predictable stable environements

• Long Life Span

• Stable population size

• Density Dependent mortality

• Multiple reproductive events later in life

• lots of parental care

• modest # of offspring

• Ex. Mammals, large animals