Exam 2 - Regis

15. Which of the following is most likely to lead to population cycles?
a. Demographic stochasticity
b. Genetic drift
c. Delayed density dependence
d. Habitat fragmentation
e. Logistic growth
16. Which of the following is a plausible consequence of delayed density dependence in a population that would
otherwise have logistic growth?
a. Increased environmental stochasticity
b. Dampened oscillations
c. Population cycles
d. Both a and b
e. Both b and c
17. According to May’s model, a population that experiences delayed density dependence can exhibit logistic
growth or dampened oscillations, or it can fluctuate forever in a stable limit cycle. Which two factors determine
the pattern that will result?
a. The population growth rate under ideal conditions and the starting population size
b. The population growth rate and the time lag
c. The starting population size and the time lag
d. The time lag and the degree of demographic stochasticity
e. The time lag and the carrying capacity
18. Suppose that a population of weevils that experiences logistic growth has an initial size of 1,563 and follows
the standard equation for delayed density dependence with a 5-week delay and an intrinsic growth rate of 0.15
per week. If these conditions remain constant and the population is tracked for a long time, what type of
population dynamics should it display? (The cutoff rτ value for dampened oscillations is 0.368, and the cutoff
for a stable limit cycle is 1.57.)
a. Exponential growth
b. Logistic growth
c. Dampened oscillations
d. A stable limit cycle
e. No change over time
19. Suppose that two species of Darwin’s finches live on the same island and eat seeds, but one species tends to
eat larger seeds than the other one does. Based on this observation, we can conclude that these species are
engaged in
a. resource partitioning.
b. allelopathy.
c. interference competition.
d. competitive exclusion.
e. character displacement.
20. Suppose that a species of moss cannot coexist with a superior competitor unless there is periodic
disturbance. This species is also a frequent disperser. Which of the following is most likely?
a. The moss is engaged in character displacement.
b. In a constant environment, the moss and its competitor have zero population growth isoclines that cross.
c. The moss is a fugitive species.
d. Both a and b
e. None of the above
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