Limiting Population Size

What happens the bigger a population grows?

The more resources are taken from the environment

What is the carrying capacity of an environment?

The maximum size of a population that an environment can support.

What does K represent in population ecology?

K represents carrying capacity.

Name the factors that can affect carrying capacity.

• Light availability

• Temperature

• Soil mineral availability

• Competition for resources

• Predation

• Disease

Factors that animals would compete for:

• Space

• Mating partner

• Water

• Food

• Shelter

• Territory

Factors than plants would compete for:

• Space

• Fertile soil

• Sunlight

• Carbon Dioxide

• Temperature

• Water

What are density-dependent factors?

Factors that depend on population size.

What are the three main groups of density dependent factors?

• Competition

• Predation

• Disease/parasitism/infestation

Competition

For limited resources

Predation

More intense if a population of prey becomes denser and less intense if the prey become more scarce

Disease/Parasitism/Infestation

Increase in population density because it is easier for pathogens, parasites and pests to spread

What are density-independent factors?

Factors that affect all population in a similar way

What are the four main groups of density independent factors?

• Environmental change

• Build up of toxins

• Injury

• Senescence (death from age related illness)

What is a negative feedback loop in population dynamics?

A self-regulating system where any deviation from steady-state is counteracted to promote stability.

Why does population size vary over time?

Due to density-independent or density-dependent factors

How do density-dependent factors regulate population size?

They cause fluctuations in population size, promoting stability over time.

More breeding/fewer deaths (population increases)

Density dependent factors cause more deaths/less breading (population decreases)

More deaths/less breading (population decreases)

Density-dependent factors cause more breeding/fewer deaths (population increases)