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Skills Worksheet

Directed Reading Section: How Competition Shapes Communities In the space provided, write the letter of the description that best matches the term or phrase.

______ 1. competition ______ 2. niche ______ 3. fundamental niche ______ 4. realized niche ______ 5. competitive exclusion ______ 6. biodiversity

a. the functional role of a particular species in an ecosystem b. the entire range of conditions an organism is potentially able to occupy c. biological interaction in which two species use the same resources d. the part of a fundamental niche that a species actually occupies e. the variety of living organisms living in a community

______ 7. species richness

f. the relative numbers of each of the species living in a community

______ 8. species diversity

g. the amount of plant material produced in a plot of land

______ 9. productivity

h. elimination of a competitive species i. the number of different species in a community

Read each question, and write your answer in the space provided.

10. What are the different niches of Chthamalus stellatus and Semibalanus balanoides?

11. What happened in Connell’s experiment with Chthamalus stellatus and Semibalanus balanoides?

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Directed Reading continued 12. Why was Chthamalus unable to compete with Semibalanus at the lower depths?

13. Why was Semibalanus unable to survive in shallow water?

Complete each statement by underlining the correct term or phrase in the brackets.

14. In the experiments by G. F. Gause, Paramecium fed on [bacteria / culture]. 15. The smaller species of Paramecium in the first experiment was [more / less] resistant to bacterial waste products. 16. The process by which the smaller species of Paramecium drove the larger species to extinction is called [survival of the fittest / competitive exclusion]. 17. In the second experiment, Paramecium caudatum [coexisted with / eliminated] Paramecium bursaris. 18. P. caudatum and P. bursaris had [different niches / the same niche]. Read each question, and write your answer in the space provided.

19. In the studies of Robert Paine, why did eliminating sea stars cause the number of species to decrease?

20. Describe two aspects of a community that biodiversity measures.

21. What is the relationship between biodiversity and productivity?

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Answer Key Directed Reading

14.bacteria 15. more 16. competitive exclusion

SECTION: HOW ORGANISMS INTERACT IN COMMUNITIES

17. coexisted with 18. different niches 19. Because sea stars preyed on mussels, eliminating sea stars caused the mussel population to increase. The mussel population crowded out many other species from the rocks. 20. Biodiversity measures the number of different species in a community and the relative number of individuals of each species. 21. The greater the biodiversity of plants in a plot, the greater is the amount of plant material the plot produces.

1. Coevolution is the back-and-forth evolu-

2.

3. 4. 5. 6. 7. 8. 9.

tionary adjustments between interacting members of an ecosystem. Secondary compounds are defensive chemicals that plants have developed to protect themselves from their predators. Predation is the act of one organism killing another for food. Parasitism is a special case of predation in which one organism, the parasite, lives on or in another organism, the host. coevolution parasitism mutualism commensalism symbiosis mutualism commensalism

SECTION: MAJOR BIOLOGICAL COMMUNITIES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

SECTION: HOW COMPETITION SHAPES COMMUNITIES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

c a b d h e i f g Chthamalus lives attached to rocks in shallow water and is exposed to air by receding tides. Semibalanus lives lower down on the same rocks and is rarely exposed to air. 11. Chthamalus was able to live at the lower depth, but Semibalanus was unable to live in shallow water. 12. Semibalanus would crowd Chthamalus off the rocks. 13. Semibalanus apparently lacked the adaptation that enabled Chthamalus to survive long exposure to air.

e g f c d b a climate temperature increases, decreases biome decrease, increases littoral zone limnetic zone profundal zone oceans plankton

Active Reading SECTION: HOW ORGANISMS INTERACT IN COMMUNITIES 1. 2. 3. 4. 5. 6.

C P, M, C P C M, C d

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