Estimating beta diversity for under-sampled communities using the variably weighted Odum dissimilarity index and OTUshuff

Abstract

Motivation: In profiling the composition and structure of complex microbial communities via high throughput amplicon sequencing, a very low proportion of community members are typically sampled. As a result of this incomplete sampling, estimates of dissimilarity between communities are often inflated, an issue we term pseudo β-diversity. Results: We present a set of tools to identify and correct for the presence of pseudo β-diversity in contrasts between microbial communities. The variably weighted Odum dissimilarity (DwOdum) allows for down-weighting the influence of either abundant or rare taxa in calculating a measure of similarity between two communities. We show that down-weighting the influence of rare taxa can be used to minimize pseudo β-diversity arising from incomplete sampling. Down-weighting the influence of abundant taxa can increase the sensitivity of hypothesis testing. OTUshuff is an associated test for identifying the presence of pseudo β-diversity in pairwise community contrasts. Availability and implementation: A Perl script for calculating the DwOdum score from a taxon abundance table and performing pairwise contrasts with OTUshuff can be obtained at http://www.ars.usda.gov/services/software/software.htm?modecode=30-12-10-00.