Final Exam, PCB 3043 – Early Version 2016 Name______
A. Life Table Problem
Giant Cassowaries, a now extinct species, were renowned for the large size of their eggs and offspring and for the investment in parental care. Before they went extinct, a small population on a south Atlantic island was followed for three years. They found:
year / eggs / 1 yr old / 2 yr old / 3 yr old / Total1 / 0 / 100 / 0 / 0 / 100
2 / 100 / 0 / 1 / 0 / 101
3 / 10 / 100 / 0 / 0 / 110
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Fill out the expected last row in the above table (8 pts) , then use the information from the table to complete the following life table (15 pts.):
year / x / lx / bx / lxbx1
2
3
4
5
(7 pts) The population on our island seems to be growing slowly. How do we expect the population to change in size over the long term? Explain the basis for your answer.
B. (10 pts.) Create equations describing the growth rates for two species involved in a mutualism. Then use these equations to determine isoclines and draw them out for us, labeling each isocline, and axis. Finally, using your graph, start with a small number of each of the two species and draw a trajectory, showing what happens to their abundances through time. Show your work.
C. (40 pts) Please give the best word as used in this class for each of the following definitions.
An area of low precipitation on the side of a mountain away from predominant winds
An assemblage of populations that interact with one another in a prescribed area or habitat
a series of stages of community change in a particular area leading toward a stable state (we want the pattern, not the process)
When increasing the abundance of a top predator causes the next trophic level to decline, the level below that to increase, etc.
Species in a food web that do not consume other species, but are either photosynthetic or detritivores
Per-capita growth rate declines at low population densities
How the capture rate of prey by a predator depends on the abundance of the prey
The numbers and relative abundances of species across a region that includes numerous local habitats
The sinking and mixing action that occurs in many water systems due to the relationship between density and water temperature
The needs and role of a species in a habitat when competition and other biotic interactions are present
Regions defined by broad vegetation types determined by patterns of precipitation and temperature
The shift from high birth and death rates to low rates, known to occur as countries develop more stable economies
When organisms directly prevent others from having access to a limiting resource, thereby increasing their own fitness
A measure of the ability of a community to persist in the presence of perturbations
A group of several local populations, linked by immigration and extinction
An interspecific interaction, where one species gains a benefit such as habitat or shelter while the other species is unaffected
Population growth when there is a constant per-capita growth rate
Variation in birth and death rates caused by changes in climatic factors such as temperature and rain
Species that consume only part of a living prey, but usually specialize on one to a few prey during their lifetime.
D. (15 pts.) Crouse et al. quantified how sensitive turtle population growth (r) is to changes in fecundity or survival of different life-history stages. So. . . . let's say in some upside-down world, turtles are invasive pests. What does the graph at right tell us as to how we might control these nasty invaders? Explain your answer clearly, including some discussion of how this graph was created.
E. Short Essays (8 pts. each for 24 pts.)
1. Describe the Janzen-Connell hypothesis. Explain why this is a density-dependent or density independent process.
2. Describe the Theory of Island Biogeography. Then explain if this process is important for metapopulations.
3. Consider the ant that live with and protect acacia. How would we know (or show) that this is really a mutualism?
G. On the right is a figure from Lubchenco's work on snails that eat algae in tide pools.
1. (8 pts.) Draw reasonable rank abundance curves in the box below for the algae when there are moderate (~125) and high (~250) numbers of snails (that is, we want two lines, one for when there are 125 snails and one for when there are 250 snails). Label your axes clearly and correctly!
2. (8 pts) Does Luchenco’s figure show an example of keystone predation? Explain your answer.
H. (15 pts.) We grow 2 species of protozoa together, with different starting conditions, and follow them for many generations. (Let’s call these species “dash” and “solid”.) We get the graphs on the right.
Draw appropriate isoclines in the plot below, based on the results of these experiments.
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