Statistical interpretation of species composition

Dean Billheimer, Peter Guttorp, William F. Fagan

Research output: Contribution to journalArticlepeer-review

213 Scopus citations


The relative abundance of different species characterizes the structure of a biological community. We analyze an experiment addressing the relationship between omnivorous feeding linkages and community stability. Our goal is to determine whether communities with different predator compositions respond similarly to environmental disturbance. To evaluate these data, we develop a hierarchical statistical model that combines Aitchison's logistic normal distribution with a conditional multinomial observation distribution. In addition, we present an algebra for compositions that includes addition, scalar multiplication, and a metric for differences in compositions. The algebra aids interpretation of treatment effects, treatment interactions, and covariates. Markov chain Monte Carlo (MCMC) is used for inference in a Bayesian framework. Our experimental results indicate that a high degree of omnivory can help to stabilize community dynamics and prevent radical shifts in community composition. This result is at odds with classical food-web predictions, but agrees with recent theoretical formulations.

Original languageEnglish (US)
Pages (from-to)1205-1214
Number of pages10
JournalJournal of the American Statistical Association
Issue number456
StatePublished - Dec 1 2001


  • Compositional data
  • MCMC
  • Multinomial regression
  • Random effects
  • Species assemblage

ASJC Scopus subject areas

  • Statistics and Probability
  • Statistics, Probability and Uncertainty


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