Ecology Population Growth Models 5

Question 1

In a source-sink metapopulation model, a 'sink' habitat is best described as one where:

Accepted Answer

Local deaths exceed local births and the patch requires immigration to persist

Answer

A sink is a habitat patch where death rates exceed birth rates (r < 0 locally), so it relies on immigration from productive 'source' patches to maintain its population.

Question 2

Which population growth model assumes that the per capita growth rate decreases as a linear function of population size?

Accepted Answer

Logistic (Verhulst) model

Answer

The logistic model assumes a linear negative relationship between population density and per capita growth rate, dropping from r at N=0 to 0 at N=K.

Question 3

A conservation biologist estimates a minimum viable population (MVP) of 500 individuals for a large mammal. This threshold is primarily set to minimize risk from:

Accepted Answer

Genetic drift, inbreeding, and demographic stochasticity

Answer

MVP estimates typically account for genetic erosion (drift, inbreeding depression) and random demographic variation that can doom very small populations even in suitable habitat.

Question 4

Environmental stochasticity in population models refers to:

Accepted Answer

Year-to-year variation in environmental conditions affecting population rates

Answer

Environmental stochasticity is random temporal variation in habitat conditions (climate, food availability) that causes the whole population's vital rates to fluctuate together.

Question 5

The Ricker model, commonly used in fisheries, produces population cycles and chaos at high values of which parameter?

Accepted Answer

The intrinsic growth rate r

Answer

At high values of r, the Ricker model (a discrete-time model) transitions from stable equilibrium to oscillations to chaos, making prediction difficult.

Ecology Practice Test

Ecology Practice Test

Ecology Population Growth Models 5