Modelling Pop Growth

Question 1

Density dependent growth

Answer 1

Is logistic growth.
Density dependent model - rate of population growth slows down as population size increases.
A more realistic model of population growth over long periods.
Assumes a closed population with no immigration or emigration.

Question 2

What shape does logistic growth model curve take

Answer 2

‘S’ shaped curve or sigmoid (asymptomatic curve)

Question 3

What is carrying capacity

Answer 3

K
The maximum population size that can be supported by the available resources
Logistic/ density dependent growth has limited resources.

Question 4

What drives time lag in density dependent response

Answer 4

Animals may survive on stored reserves and reproduce after limiting resources are depleted.
Reproductive period may be complete before the reduced affect of population

Question 5

The rate of population growth is influenced by

Answer 5

The population size at a previous time by it’s overall rate of increase
(Birth rate - death rate) and the available resources (carrying capacity)

Question 6

What’s the logistic growth formula

Answer 6

dN/dt = rN(1-N/K)

Question 7

Example of time lag in density dependent growth model

Answer 7

Daphnia store food reserves in form of oil droplets so can continue to survive and reproduce in the absence of food.
When food resources exhaust, death rate increases due to starvation and density decreases.
Due to this time lag in the response to increased density, the population continuously overshoots and undershoots the carrying capacity.

Question 8

What is logistic growth

Answer 8

It’s density dependent
Rate pop growth slows as the pop size increases
More realistic model of population growth over long periods of time
Limited resources
A shaped curve or sigmoid

Question 9

Exponential growth

Answer 9

Density independent
Pop growth rate doesn’t change as pop gets bigger.
Unlimited growth
Observed during initial cononisation of unoccupied habitats