title: Evidence for a three-way trade-off between nitrogen and phosphorus competitive abilities and cell size in phytoplankton.
abstract: Trade-offs among functional traits are essential for explaining community structure and species coexistence. While two-way trade-offs have been investigated in many systems, higher-dimensional trade-offs remain largely hypothetical. Here we demonstrate a three-way trade-off between cell size and competitive abilities for nitrogen and phosphorus in marine and freshwater phytoplankton. At a given cell size, competitive abilities 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. Our results demonstrate the multidimensional nature of key trade-offs among traits and suggest that such trade-offs may drive species interactions and structure ecological communities.
authors.affiliation: Kellogg Biological Station, Michigan State University, Hickory Corners, Michigan 49060, USA. edwar466@msu.edu
authors.forename: Kyle F
authors.initials: KF
authors.lastname: Edwards
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Klausmeier
authors.forename: Elena
authors.initials: E
authors.lastname: Litchman
mesh_terms: D048429:Cell Size; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D010839:Phytoplankton / Q000166:cytology* / Q000378:metabolism*
chemical_list: D010758:Phosphorus; D009584:Nitrogen