Nathanael I. Lichti and Michael T. Murphy. 2010. Selection ratios on community aggregated traits estimate ecological filters imposed on species by sites. Ecology 91:347–354.

Supplement 1

R source code for functions and examples of selection ratio analysis on community aggregated traits (SRCAT).
Ecological Archives


File list (downloads)


Nathanael Lichti
Department of Forestry and Natural Resources, Purdue University
715 W. State Street
West Lafayette, Indiana, USA 47907

Michael T. Murphy
Department of Biology, Portland State University
P. O. Box 751
Portland, Oregon, USA 97207-0751

File list

srcat.R -- R source code to run SRCAT analyses

srcat_examples.R -- R source code to run SRCAT examples


The function srcat() calculates the probability that a site i will select state j from k alternative versions of a discrete trait. If a continuous trait is supplied, a discrete approximation is used to estimate the selective filter imposed by i as a probability function of the trait value. Both estimations are accomplished using data on species (relative) abundance at sites (S), species possession of trait states (W), and the expected availability of species to sites, assuming no trait-based selection (A). Function parameters are described in comments within the script. The script file srcat_examples.R runs several examples of SRCAT analysis using both discrete and continuous traits.

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