Answer the following questions:
OBJECTIVE A:
Analyze the time series abundance data collected on the American redstart based on the assumption that the population follows an exponential growth model.
|
|
Answer the following questions: |
1) Assuming only process noise, based on 10 years of observation, calculate the probability that the species will fall beneath a quasi-extinction level of 2 in the next 20 years. Include a hardcopy of your results with your assignment (3 points).
2) In the 16th year of the study, what is the probability that the population of American redstarts will fall beneath 2 individual in the next 20 years? (2 points).
3) Again considering the 16th year of the study, if you think there may be some observation error associated with your estimates as well as process noise, how does the probability that the population of American redstarts will fall beneath 2 individuals in the next 20 years change? (3 points).
4) Should a manager be concerned with these results? State your rationale and include a quantitative metric to support your answer. (2 points).
OBJECTIVE B:
Using results derived from the in-class exercise, continue analyzing the Coregonus data to establish further correlations between environmental covariates and residuals of year class strength (YCS).
|
|
Answer the following questions: |
5) What is the R-squared value of the residuals of the Ricker model versus the environmental covariate number of zooplankton organisms smaller than 1 mm (SZ4)? Are these results convincing that there is a relationship between SZ4 and the abundance of whitefish? (4 points)
6) Induce a 1-year lag on the influence of dissolved oxygen on the residuals of YCS. How does the new R-squared value compare with the R-squared value obtained during the in-class exercise? Does incorporating a 1-year lag in dissolved oxygen (O2) make biological sense? Briefly explain. (4 points)
7) Hypothesize which of the other covariates in the Coregonus.xls spreadsheet might respond similarly to a time lag? Tell me why you chose that variable and how it would affect the abundance (your hypothesis), then quantitatively show me if it did or did not have a great impact (graph or equation with R2 value). Hint: To get covariate definitions you will need to read Eckmann et al. (1988). (2 points)
LITERATURE CITED
Eckmann, R., U. Gaedke, and H. J. Wetzler. 1988. Effects of climatic and density-dependent factors on year-class strength of Coregonus lavaretus in Lake Constance. Canadian Journal of Fisheries and Aquatic Sciences 45:1088-1093.
Revised: 27 October 2011