DO NOW: Today we are studying how a predator population and a prey population affect each other. Read Analysis Questions #3 and 4 and write your hypothesis in the spaces.

The Lynx

The Hare

The Lynx and Hare

Procedure Begin experiment by populating the habitat with three hares – spread them out in the square. Place the index card lynx into the square to try and land on (capture) any portion of as many hares as possible.  

Procedure The hares that are not captured should be totaled and put into the data table under “Hares Remaining”. The hares that are captured should be removed from the habitat as they did not survive.  Generation # hares # lynx Hares remaining Lynx remaining 1 3  2   2

Procedure The lynx only survives if it captures 3 or more hares. If the lynx does not capture 3 or more hares, then it will not survive. Any lynx that survives a generation should be put into the data table under “Lynx Remaining”. If the lynx only lands on 1 or 2 hare, those hare are considered captured and should be removed. However, the lynx will still not survive either. If no lynx survived the previous generation, another moves into the area, so start the next generation with 1 lynx. Generation # hares # lynx Hares remaining Lynx remaining 1 3  2  0 2    1

Procedure  The hare and lynx populations both double between generations. Therefore, double the “Hares Remaining” from the first generation as the second generation starting # of Hares. Also, double the “Lynx Remaining” from the first generation as the second generation starting # of Lynx. Generation # hares # lynx Hares remaining Lynx remaining 1 3  2  0 2  4  1  

Procedure Place the new number of hares in the square and toss the new number of lynx into the habitat.

Procedure  Repeat steps 2-6 until you have completed 20 generations. The cycle will be well on its way to repeating and the next few generations can be (relatively accurately) predicted  If the populations of either the lynx or the hare crash back to, or near zero, begin the next generations with three hares or one lynx.

Generation # hares # lynx Hares remaining Lynx remaining 1 3  2  0 2  4  1   4 5 6 7 8 9 10 11 12

DO NOW – What are the 5 unbreakable rules of graph drawing? Pencil only! 2. Use a ruler to draw straight lines. 3. Label your axes. 4. Each axis can have a separate scale, but there must be a consistent scale along the axis! 5. Use a title that tells what the graph is showing

The Lynx and Hare Graph

How to Graph Your Data: Turn your paper landscape and use a ruler to draw an “X” axis. Draw TWO “Y” axes on your graph paper because you will need to graph the population of both the lynx and the hare. Leave space for a title Leave space for a margin Leave space for a margin Leave space for a margin

How to Graph Your Data: 3. Label the X axis “Generations.” Generations

How to Graph Your Data: 4. Put a title on your Graph. Your title should give some information about what happened in the lab. An appropriate title might be “The Relationship Between Predator and Prey Populations.” “The Relationship Between Predator & Prey Populations” Generations 1 2 3 4 5 6 7 8 9 10

How to Graph Your Data: Generations Start at “0” 5. Determine how far apart you can scale the numbers on your X axis to include all of the generations you completed in your data table. If you only have 10 generations, then only graph 10 generations. If you have more generations, graph more. It is VERY important that the intersecting line between the X and Y axis is “0” and the # spaces between each generation is IDENTICAL! It is also VERY important that the X axis be as spread out as possible! “The Relationship Between Predator & Prey Populations” 1 2 3 4 5 6 7 8 9 10 Generations Start at “0”

How to Graph Your Data: 6. On the left side of your paper, label your graph “Population of Hares”. “The Relationship Between Predator & Prey Populations” 1 2 3 4 5 6 7 8 9 10 Generations Population of Hares

How to Graph Your Data: 7. Put marks on each of the y axis intersections and count how many marks you have. This example has 15 The # spaces between each generation must be IDENTICAL! The Y axis must be as spread out as possible! “The Relationship Between Predator & Prey Populations” 1 2 3 4 5 6 7 8 9 10 Generations Population of Hares

How to Graph Your Data: 8. Determine the scale for your Y axis. Find the LARGEST number of “Hares Remaining” Divide by the number of marks on the Y axis. Round UP to the nearest 10. That’s what you count each line by when you label your axis. EXAMPLE: If there are 714 hares remaining as the highest population and you have 15 marks on your graph, then divide 714 / 15= 47.6 Round up to 50. Label your graph by 50’s for each line – 0, 50, 100, 150, etc.

How to Graph Your Data: 9.) Make sure you write the numbers on the line and not between the lines. Complete all the way to 750 “The Relationship Between Predator & Prey Populations” 1 2 3 4 5 6 7 8 9 10 Generations 750 700 650 600 550 500 Population of Hares 450 400 350 300 250 200 150 100 50

How to Graph Your Data: 9. Plot the hare population over however many generations you recorded. Connect the dots with a colored pencil.

How to Graph Your Data: 10. Label the Y axis on the right side of the graph. This will be a DIFFERENT scale, for the lynxes. Population of Lynxes Generations

How to Graph Your Data: 11. Put marks on the new “Y axis” intersections. This should be the same number of marks as it was for the “Population of Hares”. This example ALSO has 15 marks on this “Y axis”. “The Relationship Between Predator & Prey Populations” 1 2 3 4 5 6 7 8 9 10 Generations Population of Hares Population of Lynxes

How to Graph Your Data: 12. Determine the scale for this “Y axis” the same way you did for the Hares. Find the LARGEST number of “Lynx Remaining” Divide by the number of marks on the Y axis. Round UP to the nearest 2. That’s what you count each line by when you label your axis. Example: If 28 is the highest hare population you had, and you have 15 marks, then divide 28/15=1.86. Round up to 2. Label your graph by 2’s – 0, 2, 4, 6, 8, 10, etc.

How to Graph Your Data: 13. Plot the hare population over however many generations you recorded. Connect the dots with a different colored pencil! Population of Lynxes Generation

How to Graph Your Data: 14.) Include a “key”. 15.) Write your name on this graph and staple it to your lab. Key Population of Lynxes Generation