Lecture 4 Flashcards
Describe the type of population where density independent exponential growth could occur
When there are few individuals and the resources are plentiful
What is the Carrying Capacity?
The maximum viable population size where a population stabilizes in a certain environment
What is the logistic growth model?
a model that incorporates the density dependent effects of declining resources on the trajectory of a population
What are the two types of density independent models?
The geometric model and the exponential model
What model is described by the equation Nt+1 = Nt(lambda)
The geometric growth model
What model is described by the equation Nt = N0e^rt
The exponential growth model
Which model is described with the equation dN/dt = rN
The exponential growth model
What model is described by the equation dN/dt = rN*(1-(N/K))
The logistic growth model
What part of the equation for the logistic growth model injects density dependence into the model?
1-(N/K)
In the logistic growth model, what happens when the population size nears the carrying capacity?
The density dependent affect (1-(N/K)) goes to 0, meaning that dN/dt = 0 and the population is stable. this means that at the carrying capacity, the population has no growth
In the logistic growth model, what happens when the population size is very small?
The density independent effect (1-(N/K)) goes to 1, meaning that dN/dt = rN which is the exponential growth model.
This means that at small populations, density dependent effects have little influence on population size over time, and the population exhibits exponential growth.
What happens when the population size exceeds the carrying capacity in the logistic growth model?
When N is larger than K, the density dependent effect become negative, making dN/dt negaive, so the population is shrinking.
What is the shape of exponential growth on a population rate of change graph?
A positive straight line
what is the shape of logistic growth on a rate of change graph?
A positive parabola
What is the shape of exponential growth on a per capita rate of change graph?
a flat line that is parallel to the x axis
What is the shape of logistic growth on a per capita rate of change graph?
A straight negative relationship
How do you determine if a population is exhibiting density dependent effects?
On a per capita rate of change graph, the relationship will not be straight and parallel to the X axis.
What kind of growth would you model with the geometric growth model?
Seasonal/pulsed growth pattern where reproduction happens during discrete time periods
What model uses lambda?
The geometric growth model
What is r?
The intrinsic rate of growth
What behaviour is exhibited by the population when r = 0?
the population is stable
What behaviour is exhibited by the population when r > 0?
The population is increasing
What behaviour is exhibited by the population when r < 0
The population is decreasing
What behaviour is exhibited by a population when lambda = 1?
The population is stable
