Ecology Population Growth Models 2

Question 1

In the logistic growth equation dN/dt = rN((K-N)/K), what does the term (K-N)/K represent?

Accepted Answer

The fraction of carrying capacity still available

Answer

The term (K-N)/K represents the proportion of the carrying capacity that has not yet been used, acting as a brake on growth as N approaches K.

Question 2

Which scenario best illustrates an Allee effect in population growth?

Accepted Answer

A population has a reduced per capita growth rate at very low densities

Answer

The Allee effect describes reduced fitness or growth rate at low population densities, often due to difficulties finding mates or cooperative defense failures.

Question 3

Doubling time for a population growing exponentially at rate r is approximately:

Accepted Answer

0.693 / r

Answer

Doubling time ≈ ln(2)/r ≈ 0.693/r, derived from the exponential growth equation N(t) = N₀e^(rt).

Question 4

A population has K = 500 and N = 250. Under logistic growth, the growth rate is at what fraction of its maximum possible rate?

Accepted Answer

50%

Answer

At N = K/2 = 250, the logistic braking term equals 0.5, so growth rate is 50% of its theoretical maximum rN.

Question 5

What distinguishes a Leslie matrix model from simple exponential or logistic growth models?

Accepted Answer

It tracks age- or stage-structured survival and fecundity

Answer

Leslie matrix models track survival rates and fecundity for distinct age or stage classes, producing more realistic projections for structured populations.

Ecology Practice Test

Ecology Practice Test

Ecology Population Growth Models 2