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Population estimates for California Condors were collected from 1965 to 1980 (see file Condor.inp). Use program STOCHMVP to analyze these data. Assume the initial population size (N0) = 45, and you set the quasi-extinction threshold (Ne) = 35, time = 40 yrs, and desired probability of persistence = 0.80.
| 1a. | (i) What is the mean instantaneous rate of growth (mu) for this population? (ii) What is the variance associated with mu? |
| 1b. | What is the minimum viable population (MVP) size for this species assuming one population, time = 40 years, with a desired probability of persistence of 0.80? |
| 1c. | What is the probability of persistence for the initial population size of 45? (note: this value may scroll past your viewing screen on the first try, but it can be viewed by entering a large number when asked for # of subpopulations). |
| 1d. | (i)What is the MVP size for the metapopulation if it consists of 2 subpopulations? (ii) What is the size of each subpopulation? (hint: think about how program STOCHMVP treats subpopulations). (iii) What is the probability of extinction for each subpopulation? (iv) What is the probability of persistence for the metapopulation? |
| 1e. | If the subpopulations were not independent, but all else was equal, would the MVP for the metapopulation be larger or smaller than calculated in question #1d(i)? Explain your answer. |
| 1f. | The population still consists of 45 individuals but an intensive habitat
and population management program has resulted in an increasing Condor population ( mu
= 0.223, variance same as calculated above). Rerun the analysis but enter the new value
for mu. (i) What is the new MVP for this population? (ii) What is the probability of the initial population persisting for the next 40 years? (iii) Compare these results to the original analysis. Why are MVP values different? |
Use program INMAT2AC to answer the following questions (include output from INMAT2AC with your answers!).
| 2. | Run the stochastic model with the following data: No = 7, low growth rate (ungulate population with lambda = 1.05), CV (environmental stochasticity) = 0, inbreeding costs = 0. (a) What percent of the 40 replicates (simulated populations) went extinct? (b) What was the mean population size (females only) at time-step 5? at time-step 10? (c) What was the expected population size, given deterministic growth, at time step 5 and 10? Hint: Nt = N0 (lambda)t . Show your work. |
| 3. | Run the stochastic model with the following data: N0 = 7, high
growth rate (rodent population with lambda=1.56), CV=0, inbreeding costs = 0. (a) What percent of the 40 replicates went extinct? (b) What was the mean female population size at time-step 10? (c) What was the expected population size, given deterministic growth, at time-step 10? Show your work. |
| 4. | Rerun the data from question #2 and #3, but now incorporate a moderate
amount of environmental stochasticity (i.e., set CV=0.32). (a) Construct a table that compares:
(b) Discuss possible reasons for any observed differences among the 3 simulations. Hint: think about the stochastic and deterministic factors that were modeled in each case, and the factors that are known to affect population persistence (see lab notes). |
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