Lab 6:  In-class Exercise

Density Dependent Population Growth:

Use Excel to complete the following exercises (click here for a data template)....

1.  For this scenario, let's say there was Ricker-type density dependent growth in the pheasant population.  Under the best of conditions (i.e., population size = 0) the pheasant population can double (i.e, lambda = 2).  However, as population sizes increase, growth rate decreases and the intraspecific competition coefficient is  b = -0.0035.

1) What is r(max) and the carrying capacity for this population?

 

2) Starting in 1980 with an initial abundance of 2, calculate and plot the population size for the next 20 years (i.e., 1981 - 2000).

 

3) Plot the instantaneous growth rate (i.e., ln[n(t+1)/n(t)]) versus population size [n(t)].

 

2.  For this scenario, let's say there was Gompertz-type density dependent growth in the pheasant population.  Again, assume under the best conditions (i.e., population size = 1), the pheasant population can double (i.e., lambda = 2).  However, as population sizes increase, growth rate decreases and the intraspecific competition coefficient under the Gompertz model is  b = -0.131.

1) What is r(max) and the carrying capacity for this population?

2) Starting in 1980 with an initial abundance of 2, calculate and plot the population size for the next 20 years (i.e., 1981 - 2000).

3) Plot the instantaneous growth rate (i.e., ln[n(t+1)/n(t)]) versus population size [n(t)].  What happens when you plot instantaneous growth rate versus log-abundance (i.e., ln[n(t)]).

4) Compare with plots of Ricker growth.

3.  Estimate the parameters, r(max), b, and K for the Ricker and Gompertz models given the following time-series:

Revised: 23 September 2011