1. Constrained Ordination Analysis with Enrichment of Bell-Shaped Response Functions.
- Author
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Zhang, Yingjie and Thas, Olivier
- Subjects
SPECIES diversity ,ECOLOGICAL niche ,MICROBIAL ecology ,METAGENOMICS ,ORDINATION (Statistics) ,REGRESSION analysis ,LIKELIHOOD ratio tests - Abstract
Constrained ordination methods aims at finding an environmental gradient along which the species abundances are maximally separated. The species response functions, which describe the expected abundance as a function of the environmental score, are according to the ecological fundamental niche theory only meaningful if they are bell-shaped. Many classical model-based ordination methods, however, use quadratic regression models without imposing the bell-shape and thus allowing for meaningless U-shaped response functions. The analysis output (e.g. a biplot) may therefore be potentially misleading and the conclusions are prone to errors. In this paper we present a log-likelihood ratio criterion with a penalisation term to enforce more bell-shaped response shapes. We report the results of a simulation study and apply our method to metagenomics data from microbial ecology. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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