TY - JOUR
T1 - The effects of dynamical rates on species coexistence in a variable environment
T2 - The paradox of the plankton revisited
AU - Li, Lina
AU - Chesson, Peter
N1 - Funding Information:
We are grateful for comments on the article from J. Chase, K. Dlugosch, J. Fox, and J. Levine. This work was supported by National Science Foundation grant DEB-1119784.
Publisher Copyright:
© 2016 by The University of Chicago. All rights reserved.
PY - 2016/8
Y1 - 2016/8
N2 - Hutchinson’s famous hypothesis for the “paradox of the plankton” has been widely accepted, but critical aspects have remained unchallenged. Hutchinson argued that environmental fluctuations would promote coexistence when the timescale for environmental change is comparable to the timescale for competitive exclusion. Using a consumer-resource model, we do find that timescales of processes are important. However, it is not the time to exclusion that must be compared with the time for environmental change but the time for resource depletion. Fast resource depletion, when resource consumption is favored for different species at different times, strongly promotes coexistence. The time for exclusion is independent of the rate of resource depletion. Therefore, the widely believed predictions of Hutchinson are misleading. Fast resource depletion, as determined by environmental conditions, ensures strong coupling of environmental processes and competition, which leads to enhancement over time of intraspecific competition relative to interspecific competition as environmental shifts favor different species at different times. This critical coupling is measured by the covariance between environment and competition. Changes in this quantity as densities change determine the stability of coexistence and provide the key to rigorous analysis, both theoretically and empirically, of coexistence in a variable environment. These ideas apply broadly to diversity maintenance in variable environments whether the issue is species diversity or genetic diversity and competition or apparent competition.
AB - Hutchinson’s famous hypothesis for the “paradox of the plankton” has been widely accepted, but critical aspects have remained unchallenged. Hutchinson argued that environmental fluctuations would promote coexistence when the timescale for environmental change is comparable to the timescale for competitive exclusion. Using a consumer-resource model, we do find that timescales of processes are important. However, it is not the time to exclusion that must be compared with the time for environmental change but the time for resource depletion. Fast resource depletion, when resource consumption is favored for different species at different times, strongly promotes coexistence. The time for exclusion is independent of the rate of resource depletion. Therefore, the widely believed predictions of Hutchinson are misleading. Fast resource depletion, as determined by environmental conditions, ensures strong coupling of environmental processes and competition, which leads to enhancement over time of intraspecific competition relative to interspecific competition as environmental shifts favor different species at different times. This critical coupling is measured by the covariance between environment and competition. Changes in this quantity as densities change determine the stability of coexistence and provide the key to rigorous analysis, both theoretically and empirically, of coexistence in a variable environment. These ideas apply broadly to diversity maintenance in variable environments whether the issue is species diversity or genetic diversity and competition or apparent competition.
KW - Competitive exclusion
KW - Covariance between environment and competition
KW - Nonequilibrium coexistence
KW - Storage effect
KW - Temporal environmental variation
KW - Temporal scale
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U2 - 10.1086/687111
DO - 10.1086/687111
M3 - Article
C2 - 27420794
AN - SCOPUS:84978745470
SN - 0003-0147
VL - 188
SP - E46-E58
JO - American Naturalist
JF - American Naturalist
IS - 2
ER -