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Module 9S1 Ecological Interactions

Lesson 4.9.1S1

4.9.1S1 page 3

Self-Check 2


SC 1. Complete this Self-Check activity.

 

Try This

TR 1. Check out the typical predator/prey cycle graph in Figure 20.12 on p. 721. 

  1. If you were not shown the legend, how would you know which line represents predator, and which represents prey? Hints:
     
    • Which would always have the highest numbers? (think food pyramid)
    • How long would it take for an excess of prey to translate to an excess of predator? (High food supply expresses itself as more babies being born the following season)
  2. What is the length of the lynx-hare cycle in years?
Check your work.
Try This Answers

TR 1.

  1. The prey species is always highest in number, the predator is lower, so the purple line must be the predators. The excess of prey will translate to increased number of births the next breeding season - the offspring born the next year. So, high prey translates to high number of predators in the year or two after the prey spike, so the purple line must indicate the predators.
       
  2. Count crest to crest or trough to trough. The cycle is approximately 10 years long
Discuss

Deer and moose hunters pride themselves on the size of the animal taken and the # of tines on the antlers (# of tines increases with the age and size of the buck). Both hunters and predators keep the prey population in check. However, hunters tend to have a negative effect on the prey gene pool whereas predators have a positive effect.

Prepare reasons for this distinction. What kind of hunting regulations would correct this problem? Post your work on the discussion board, and discuss the work of other students. Summarize the thoughts of the group and put the summary in your course folder.

 

Module 9: Section 1—Lesson 1 Assignment

Submit your completed Module 9: Section 1—Lesson 1 Assignment to your teacher for assessment.

Lesson Summary

In this lesson you have studied the following concepts:

  • What are the relationships that exist between species and ecosystems?
  • What is the effect these interactions have on population changes: 

You should now have come to appreciate the many types of living relationships that can help, harm, or have little effect on interacting species.