Journal Article

Environs: The Superniches of Ecosystems

Bernard C. Patten
American Zoologist
Vol. 21, No. 4, Theoretical Ecology (1981), pp. 845-852
Published by: Oxford University Press
Page Count: 8
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Environs: The Superniches of Ecosystems
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Evolution proceeds by natural selection of heritable variations of individual organisms based on direct influences of environment. However, indirect effects probably vastly outweight direct ones in ecosystems. Therefore, why is evolution based on direct effects only? The ecological niche represents the point of direct contact between organisms and their environments. To encompass indirect influences, niches are extended to new structures, environs, which are units of organism-environment coevolution. The motive force for coevolution is closure of outputs back upon inputs of the organism members of ecosystems. Closure is achieved by biogeochemical cycling and feedback interactions, direct and indirect, between organisms. To the extent that closure does not occur, there is no imperative for organism-environment coevolution. Coevolution at the system level based on indirect effects is compatible with normal evolution at the individual organism level based on direct effects. The organism is the unit of the latter, but environs are the unit of coevolution.