coexistence via resource partitioning fails to generate an increase in community function共存通过资源分区不能生成增加社区功能.pdf
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Coexistence via Resource Partitioning Fails to Generate
an Increase in Community Function
John P. DeLong*, David A. Vasseur
Yale University, Department of Ecology and Evolutionary Biology, New Haven, Connecticut, United States of America
Abstract
Classic ecological theory suggests that resource partitioning facilitates the coexistence of species by reducing inter-specific
competition. A byproduct of this process is an increase in overall community function, because a greater spectrum of
resources can be used. In contrast, coexistence facilitated by neutral mechanisms is not expected to increase function. We
studied coexistence in laboratory microcosms of the bactivorous ciliates Paramecium aurelia and Colpidium striatum to
understand the relationship between function and coexistence mechanism. We quantified population and community-level
function (biomass and oxygen consumption), competitive interactions, and resource partitioning. The two ciliates
partitioned their bacterial resource along a size axis, with the larger ciliate consuming larger bacteria than the smaller ciliate.
Despite this, there was no gain in function at the community level for either biomass or oxygen consumption, and
competitive effects were symmetrical within and between species. Because other potential coexistence mechanisms can be
ruled out, it is likely that inter-specific interference competition diminished the expected gain in function generated by
resource partitioning, leading to a system that appeared competitively neutral even when structured by niche partitioning.
We also analyzed several previous studies where two species of protists coexisted and found that the two-species
communities showed a broad range of biomass levels relative to the single-species
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