COS 40-9 - Evidence for a three-way tradeoff between nitrogen and phosphorus competitive abilities and cell size in phytoplankton

Tuesday, August 9, 2011: 4:40 PM
9AB, Austin Convention Center
Kyle F. Edwards , W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI
Christopher Klausmeier , W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI
Elena Litchman , W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI
Background/Question/Methods

Tradeoffs among functional traits are essential for explaining community structure and species coexistence. While two-way tradeoffs have been investigated in many systems, higher-dimensional tradeoffs remain largely hypothetical. Here we use a literature compilation of phytoplankton traits, in combination with a population dynamic model, to characterize the multivariate relationships among competitive ability for nitrogen, competitive ability for phosphorus, and cell size. 

Results/Conclusions

We demonstrate a three-way tradeoff between cell size and competitive abilities for nitrogen and phosphorus, in marine and freshwater phytoplankton. At a given cell size, competitive ability for N and P are negatively correlated, but as cell size increases, competitive ability decreases for both nutrients. The relative importance of the two trade-off axes appears to be environment-dependent, suggesting different selective pressures: freshwater phytoplankton separate more along the N vs. P competition axis, and marine phytoplankton separate more along the nutrient competition vs. cell size axis.

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