Early Cambrian food webs on a trophic knife-edge? A hypothesis and preliminary data from a modern stromatolite-based ecosystem

James Elser, James Watts, John H. Schampel, Jack Farmer

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Here we use the theory of ecological stoichiometry to propose and provide a preliminary test of a novel hypothesis that the Cambrian 'explosion' may have been triggered by changes in circulating P availability in the biosphere. We exposed living stromatolites from a spring-fed stream in Mexico to a gradient of P enrichment to examine subsequent effects on stromatolite C: P ratio and on the primary grazer, an endemic snail. Consistent with a previously hypothesized stoichiometric 'knife-edge', snail performance was maximal at intermediate P-enrichment, indicating in situ stoichiometric constraints because of high stromatolite C: P ratio along with high sensitivity to excessive P intake. These results are consistent with the idea that stoichiometric constraints may have delayed the evolutionary proliferation of animals in ancient stromatolite-dominated ecosystems and also suggest that high food P content can significantly impair consumers. We propose that ecosystem P availability may have impacted both the expansion and decline of animal taxa in the history of life.

Original languageEnglish (US)
Pages (from-to)295-303
Number of pages9
JournalEcology letters
Volume9
Issue number3
DOIs
StatePublished - Mar 2006

Keywords

  • Cambrian explosion
  • Ecological stoichiometry
  • Phosphorus
  • Snails
  • Stromatolites

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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