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, University of Hawaii, Honolulu, HI, Christopher Klausmeier, Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI and Elena Litchman, W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI

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. 


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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