In David Tilman's Experiments with the Diatoms Cyclotella and Asterionella

question 20

Multiple Choice

In David Tilman's experiments with the diatoms Cyclotella and Asterionella, when the diatoms were grown at silicon/phosphorus ratios between 6 and 90, why did the two species coexist?

• A) Both species were phosphorus limited.
• B) Both species were silicon limited.
• C) Neither species was limited by phosphorus or silicon.
• D) One species was limited by phosphorus, and the other was limited by silicon.
• E) Tilman continually supplemented the cultures with individuals of the two species.

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