Week 3 Population Ecology

What do feedback mechanisms do?

bring the population back to equilibrium population size

What controls the upper limit of population density?

Ecological mechanisms

What is the difference between intrinsic and extrinsic factors that affect population growth?

Intrinsic - happen from within the population

Extrinsic - happen from outside the population

What are examples of intrinsic factors that affect population growth?

Stress

Intraspecific competition

Territoriality

Density dependent dispersal

Is this a discrete or continuous time model?

Discrete logistic time model

What does this equation show?

Logistic growth in continuous time

What is logistic growth an example of?

Density dependent population growth

What happens in negative density dependence?

As population density increases the growth rate decreases

What happens in positive density dependence (Allee effect) ?

At low population size growth rate decreases

per capita population growth rate

What does this graph show?

Negative density dependence

When population size increase the death rate increase

So net growth rate decrease

The population is pushed towards the equilibirum which is K

If r tau is small it produces a?

Logistic model

If r tau is intermediate it produces?

Damped oscillations

If r tau is large it produces a?

Stable limit cycle