4b. Change the Age 1 mortality rate to 0.3. Run the simulation starting with 75 individuals, all in Age class 1. What happens? Is this a stochastic model? If not, why does it look like it has a random component?
No. It shows no randomness whether initial Age 1 population is 75 or 1000. Setting the time stamp to 0.1 eliminates the appearance of randomness.
What if we have imperfect knowledge about birth rate? The data we have are consistent with a birth rate bb as low as 0.15 and as high as 0.35. Run the model with the lowest and the highest possible birth rate. Now use the “Compare Results” tool (under the “Tools” menu in the upper right corner…) to visualize the range of possible population growth trajectories that would be possible given our uncertainty about the per-capita birth rate.
. Provide the plot you just made in your write-up. What is the range of possible final abundances after 15 years? Can we conclude that the population growth rate is positive in this population?
Is the effect of demographic stochasticity bigger at low or high abundances? low populations are more susceptible. The smaller the population, the greater the risk of extinction resulting from fluctuations caused by demographic stochasticity.
