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Predator/Prey Relationship
Rubric
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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