BIOE 440 Conservation Biology, Take home test, due FRI 11/13 in class
NAME_______________________________________
Please do this test on your own. I recommend that you put the data into R or Excel at the
beginning, and do all the work there, which will help to avoid rounding errors or other
simple math errors. You can then use cut & paste to insert material into your answers
here, or transcribe them by hand.
1. (A) Complete the life table.
Age in
years
x
0
1
2
3
4
5
6
Number
Alive
Nx
100
80
64
51
31
10
0
Fecundity Survivorship
from birth
mx
lx
0
0
0.6
1.09
0.2
0
--
Annual
survival
sx
(B) Assuming that the population is growing exponentially, what is the expected
population size in ten years (ignoring age structure and stochasticity)? Show your work.
2. Show the survivorship curve (on a log-linear plot) for this population and briefly state
what it reveals about patterns of age-specific survival in this population.
3. The data in the life table above already account for juvenile survival, because they
were collected with continuous population monitoring. In this case, you do not have to
convert fecundity values before putting them into a Leslie matrix. Explain how you
would calculate fecundity (Fx) values for a Leslie matrix if the data had been collected
with a pre-breeding census. Explain why this adjustment is needed with a pre-breeding
census. An equation and diagram will be useful.
4. (A) Show the Leslie matrix for the life table above.
(B) Using the Leslie matrix and the number of individuals in each age class from the data
on the table, calculate the number of individuals in each age class after one year. Show
your work for rows one and two.
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BIOE 440 Conservation Biology, Take home test, due FRI 11/13 in class
NAME_______________________________________
5. Determine the expected stable age distribution for this population. Compare the stable
age distribution to the actual age distribution from the number of individuals in each age
class in the life table above– making the comparison graphically would show the
similarities and differences most clearly. What does this comparison suggest about the
recent stability (or lack of stability) of the population’s birth and death rates?
Age
Stable age distribution
(% of population)
Observed age distribution
(% of population)
0
1
2
3
4
5
6. Using the set of lion counts in the table below, use a count-based PVA approach to
estimate (A) the arithmetic mean annual growth and the geometric mean annual growth,
and (B) the probability that population size will drop below 100 within the 20 years after
1982. In stating your results, include a brief statement of the important assumptions of
your analysis. (C) Given your answer to part A and part B, briefly state why a population
whose mean growth rate is positive can still have a risk of extinction (or pseudoextinction, in this case)?
Year
Lion Count
1963
109
1964
125
1965
222
1966
189
1967
250
1968
165
1969
150
1970
147
1971
132
1972
250
1973
229
1974
323
1975
250
1976
124
1977
209
1978
138
1979
144
1980
149
1981
173
1982
186
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