TY - JOUR
T1 - Functional trait space and the latitudinal diversity gradient
AU - Lamanna, Christine
AU - Blonder, Benjamin
AU - Violle, Cyrille
AU - Kraft, Nathan J.B.
AU - Sandel, Brody
AU - Šímová, Irena
AU - Donoghue, John C.
AU - Svenning, Jens Christian
AU - McGill, Brian J.
AU - Boyle, Brad
AU - Buzzard, Vanessa
AU - Dolins, Steven
AU - Jørgensen, Peter M.
AU - Marcuse-Kubitza, Aaron
AU - Morueta-Holme, Naia
AU - Peet, Robert K.
AU - Piel, William H.
AU - Regetz, James
AU - Schildhauer, Mark
AU - Spencer, Nick
AU - Thiers, Barbara
AU - Wiser, Susan K.
AU - Enquist, Brian J.
N1 - Publisher Copyright: © 2014 PNAS.
PY - 2014/9/23
Y1 - 2014/9/23
N2 - The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory.
AB - The processes causing the latitudinal gradient in species richness remain elusive. Ecological theories for the origin of biodiversity gradients, such as competitive exclusion, neutral dynamics, and environmental filtering, make predictions for how functional diversity should vary at the alpha (within local assemblages), beta (among assemblages), and gamma (regional pool) scales. We test these predictions by quantifying hypervolumes constructed from functional traits representing major axes of plant strategy variation (specific leaf area, plant height, and seed mass) in tree assemblages spanning the temperate and tropical New World. Alpha-scale trait volume decreases with absolute latitude and is often lower than sampling expectation, consistent with environmental filtering theory. Beta-scale overlap decays with geographic distance fastest in the temperate zone, again consistent with environmental filtering theory. In contrast, gamma-scale trait space shows a hump-shaped relationship with absolute latitude, consistent with no theory. Furthermore, the overall temperate trait hypervolume was larger than the overall tropical hypervolume, indicating that the temperate zone permits a wider range of trait combinations or that niche packing is stronger in the tropical zone. Although there are limitations in the data, our analyses suggest that multiple processes have shaped trait diversity in trees, reflecting no consistent support for any one theory.
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U2 - 10.1073/pnas.1317722111
DO - 10.1073/pnas.1317722111
M3 - Article
C2 - 25225365
SN - 0027-8424
VL - 111
SP - 13745
EP - 13750
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 38
ER -