Population Size and Growth

When going up trophic levels, most energy is used for metabolism, with the rest being lost as heat

• 10% rule - approximately only 10% of the energy from one trophic level is transferred to the next, with 90% lost, mainly as heat through respiration

How are population sizes controlled in an ecosystem?

• carrying capacity - the max population size an ecosystem can support

• regulators of population size

  • intraspecific competition for food, water, space, and other resources

  • predators

  • infectious/contagious diseases

  • competition with other species

  • mates/reproductive success

Growth Formulas

(birth - deaths)/population = growth rate

growth rate x population size = exponential growth

population size x growth rate ((carrying capacity - pop. size)/carrying capacity)) = logistic growth