Question

population dynamics: predator - prey
moose first swam to isle royale in the early 1900s. wolves followed several
decades later, traveling over the ice from canada in the 1940s. about 40 years
into the study, the wolf population crashed when humans introduced the canine-
parovirus. additional factors over the years have impacted both populations.
shortly before 2009, the moose population collapsed during the most severe winter
on record followed by an outbreak of moose ticks. in the spring of 2010, scientists
used an insecticide spray to kill the moose ticks of isle royale. describe how this
action will change the graph.
a there would be a rise in the line representing the moose
population that following summer, but it would decline once the
winter set in.
b we would expect a gradual rise in the line representing the
moose population first, then followed by a rise in the line
representing the wolves.
c since the scientists killed off the ticks, we would see a rapid
rise in the moose population, followed quickly by a rapid rise in
the wolf population.
d the line representing the moose population would level out at
500 for the next several years while the wolves would remain
constant at about 1500, no change from the numbers seen in
summer 2009.

Explanation:

In a predator - prey relationship, when the prey (moose) population is affected by a factor that reduces its limiting factors (in this case, ticks), the moose population will first increase. As the moose population increases, there is more food available for the predators (wolves), so the wolf population will also increase. Option A only considers a short - term and not the predator - prey relationship. Option C's "rapid" rise is an over - simplification as ecological changes are usually more gradual. Option D ignores the predator - prey dynamics.

Answer:

B. We would expect a gradual rise in the line representing the moose population first, then followed by a rise in the line representing the wolves.