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## San Diego State University Elk Population Growth Analysis (a) What is going on in the plot above? What does it imply about the elk population that you are

San Diego State University Elk Population Growth Analysis (a) What is going on in the plot above? What does it imply about the elk population that you are
studying? Briefly explain. (b) Using the information given above, add new lines on the graph above for the predicted popu-
lation trajectory (how your population density changes over time) if your elk population started at
an initial population size of: A) 200 individuals, B) 75 individuals, or C) 10 individuals. (c) Using the information given above, draw the predicted relationship between population density
and per capita population growth rate on the plot below. To the right, briefly explain why you
drew what you did (d) For the following four population densities, label the points on the second graph with their
letter, and then use the graph to write down your estimate of the per capita population growth rate
at that density: A) 200 individuals: B) 75 individuals:
C) 10 individuals: D) 150 individuals:
(e) A new herd of deer is introduced into your study area. Deer and elk are both herbivores, and
both consume leaves, low branches and bark of shrubs and small trees. In the wild, deer and elk
are often found living in the same areas. Compared to your first plot, how would you expect your
population density of elk to change when deer are introduced? Why? Explain, with reference to
the relevant interspecific interaction (f) Elk also consume many wild grass species. Using the information about this elk population
above, would you expect those grass species to exhibit constitutive or induced defenses against
herbivory? Why? Justify your answer, and include a definition of induced and constitutive defense
150
Population density
100
50
0
0
10
20
30
40
Time (days)
3
3
2
1
Per capita population growth rate
0
-1
-2
0
50
100
150
200
250
Population density

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