title: Can interaction coefficients be determined from cencus data?
abstract: The method of estimating interactions proposed independently by Pimm and Schoener is studied using field data from the community of rodents which lives in the arid, rocky habitats of Israel. One important problem the method addresses is how to remove the effects of habitat heterogeneity on the estimate. We tried six different variations of the analysis scheme outlined by Crowell and Pimm, and found their results qualitatively inconsistent. This was especially true when we compared the results produced from separate habitat variables with those produced from the principal components of the habitat variation.Another problem, this one not previously addressed, is great variation in the average abundance of the different species. We discovered that the ratio of the average abundances of two species is the best predictor of the value of their coefficients of interaction. Common species appear to have weak influence on rare ones; rare ones appear to have strong influence on common ones. The statistical mechanism which produces this relationship is clear, indicating that the relationship is an artifact.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, 85721, Tucson, AZ, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Rosenzweig
authors.affiliation: Department of Biology, Ben-Gurion University of the Negev, Beersheva, Israel.
authors.forename: Zvika
authors.initials: Z
authors.lastname: Abramsky
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, 85721, Tucson, AZ, USA.
authors.forename: Burt
authors.initials: B
authors.lastname: Kotler
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, 85721, Tucson, AZ, USA.
authors.forename: William
authors.initials: W
authors.lastname: Mitchell