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Contributed by: Council of Chief State School Officers (CCSSO)
ME 406: Population Dynamics
Item #1
Item Description: To develop a clearer understanding
of the research data in the chart, you have decided to graph the
population of the two animals. You will construct a line graph,
label it clearly, and plot the data points. Designate the snowshoe
hare population numbers with a dot (.) and the lynx population number
with "x". Based on the data you have graphed, explain the relationship,
if any, between the populations of lynx and snowshoe hares.
Content Definition: The snowshoe hare is an
herbivore while the lynx is an herbivore while the lynx is a carnivore
and predator of the hare. Herbivores and carnivores tend to have
very different breeding patterns that affect how the total population
number change in their respective species. The predator/prey relationship
explains that an increase in the snowshoe hare population (prey)
leads to an increase in the lynx population (predator). The increase
of the hare population (due to the vegetation growing season, not
just the absence of lynx) leads to the increase of the lynx population.
Eventually the increase in lynx population (along with the annual
change in vegetation) impacts the hare's base population number
and the hare population falls off. Then the lynx population decreases.
Time elapsed
years |
Population of
snowshoe hare
(thousands) |
Population of
lynx
(hundreds) |
| 0 |
20 |
10 |
| 2 |
55 |
15 |
| 4 |
65 |
55 |
| 6 |
95 |
60 |
| 8 |
55 |
20 |
| 10 |
5 |
15 |
| 12 |
15 |
10 |
| 14 |
50 |
60 |
| 16 |
75 |
60 |
| 18 |
20 |
10 |
| 20 |
25 |
5 |
| 22 |
50 |
25 |
| 24 |
70 |
40 |
| 26 |
30 |
25 |
| 28 |
15 |
5 |
Scoring Parameters: Adequate responses will include the following:
- Create a graph of the data to facilitate accurate analysis.
- Correctly analyze the graph by noting three aspects of the
graph:
- The difference in population size between the lynx and the
hare.
- The cyclic nature of the sizes of each population.
- The time lag between the population's cyclical fluctuations.
Score Level Descriptions:
| NS |
No attempt to graph (labels, numbers or plotting
of any of the data onto the grid) is present. No adequate analysis
(demonstration of understanding of the relationship between
the snowshoe hare and lynx population by mentioning any of the
aspects of the graph) is given. |
| 1 |
Student demonstrates limited understanding of
graphing and limited understanding of the relationship between
the snowshoe hare and lynx populations. Example: An attempt
to graph (labels, numbers or plotting of any of the data onto
the grid) may be present. No adequate analysis (demonstration
of understanding of the relationship between the snowshoe hare
and lynx population by mentioning any aspects of the graph)
is given. Student may indicate something about the data or,
the trends or, the labels of their graph. |
| 2 |
Student demonstrates some understanding of graphing
and some knowledge of the relationship between the snowshoe
hare and lynx populations. For example, the graph is constructed,
the trends are accurate, and some data for the hare or the lynx
is correctly plotted (but may be in thousands, not hundreds)
or missing. The answer suggests that the student does not understand
the relationship between the snowshoe hare and lynx populations
OR the graph is not constructed correctly and plotted
accurately, but the answer does demonstrate that the student
understands the relationship between the snowshoe hare and lynx
populations by mentioning at least one aspect of the graph. |
| 3 |
Student demonstrates adequate understanding of
graphing and adequate knowledge of the relationship between
the snowshoe hare and lynx populations. Example: The graph is
constructed correctly and data for the hare is plotted adequately
(no more than three data points misplotted). Data for the lynx
may be plotted in thousands, not hundreds, but has been adequately
plotted (no more than three data points misplotted). An answer
that demonstrates the understanding of the relationship between
the snowshoe hare and lynx populations by mentioning at least
two aspects of the graph is present (i.e., and increase in hare
population leads to a lynx population increase; there is a delay
in the change of the populations of snowshoe hare and lynx;
there are ten times as many hares as lynx). |
| 4 |
Student demonstrates a high level of understanding
of graphing and a high level of knowledge of the relationship
between the snowshoe hare and lynx populations. The graph is
constructed correctly and data for the hare and lynx is plotted
accurately. The difference in scale of the hare data and the
lynx data is accurate. The correct analysis of the data is made
by noting the three aspects of the graph. The delay in the change
of the populations is noted (i.e., when the lynx population
increases, years later the snowshoe hare population begins to
decrease, and when the snowshoe hare population decreases, years
later the lynx population begins to decrease). |
ME 406: Population Dynamics
Item #2
Item Description: Write a brief response to
the members of the sub-committee stating whether you support or reject
the proposal to reduce the lynx population. Explain your position
based on the research data.
This item assesses the student's ability to:
- communicate scientific information graphically by calibrating,
plotting data, and interpreting data;
- examine scientific data to determine a relationship between
the populations of two animal species that are in a predator/prey
relationship; and
- write a report that represents a position relating to a decision
that affects the success of a population of animal species.
Content Definition: Data from the graph or
chart from the previous items should be included in responses to
this item because this item focuses on a human intervention into
the relationship developed in the previous question. Changes in
the hare population are primarily due to BOTH the vegetation
growing season and the rate of change in the lynx population.
Changes in the lynx population are primarily due to the rate of
change of the hare population. The lynx population change is more
dependent on the hare population change than vice versa and is a
"lagging indicator" of the hare population.
Given a constant food supply for the hare, the lynx population
eventually would increase to a level where the hare population could
not sustain itself. Add to this equation the variability of the
vegetation growing season and the changes in lynx population, and
you get population decreases and increases (a cycle) over time for
hares. Later, the lynx population changes because of the decreasing
and increasing number of prey.
Therefore, decreasing the lynx population without knowing the
current hare-lynx population cycle could needlessly disrupt the
natural population cycle of both species. Reducing the lynx population
would remove one natural limiting factor on the hare population.
Scoring Parameters: Adequate response will:
- State if the proposal to reduce the lynx is supported or rejected
by the student.
- Defend their position by citing information from the graph chart
of hare and lynx population.
Score Level Descriptions:
| NS |
Student does not indicate choice of support or
rejection of the proposal and says nothing about the data and
offers no advise. |
| 1 |
Student demonstrates limited understanding and
knowledge of the relationship between the lynx and the snowshoe
hare populations. Example: Student either takes a position on
the proposal OR mentions something about the lynx and
hare or predators and prey in general. |
| 2 |
Student demonstrates some understanding and knowledge
of the relationship between the lynx and the snowshoe hare populations.
Example: Student takes a position and offers some kind of acceptable
explanation or rationale relating to the predator/prey relationship
between the lynx and the hare OR the student does not
indicate support or rejection of the proposal and the explanation
presented demonstrates limited understanding of the predator/prey
relationship between the lynx and the hare. |
| 3 |
Student demonstrates adequate understanding and
knowledge of the relationship between the lynx and the snowshoe
hare populations by taking a position on the proposal and defends
that position in some detail. For example, a clear statement
of whether the student supports or rejects the proposal is present,
AND the explanation presented mentions the data from
the graph, but fails to incorporate the importance of the predator/prey
relationship to the long term constancy of the populations,
OR does not state the population changes do not occur
simultaneously. |
| 4 |
Student demonstrates a developed understanding
and applies knowledge of the relationship between the lynx and
the snowshoe hare populations. Students takes a position on
the proposal and defends that position by citing information
from the graph or chart. The explanation is well developed and
notes that a solution is difficult to develop given the lag
time in population changes noted on the previous graph or something
else (specific) about living organisms. For example, a clear
statement of whether the student supports or rejects the proposal
is present, AND explains the importance of understanding
the cyclical nature of predator/prey relationships in the long
term, AND states that the population changes do not occur
simultaneously. |
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