Constrained Ordination Analysis with Enrichment of Bell-Shaped Response Functions.
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.
Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Coupure Links 653, Ghent 9000, Belgium.
Yingjie
Y
Zhang
Department of Mathematical Modelling, Statistics and Bioinformatics, Ghent University, Coupure Links 653, Ghent 9000, Belgium.|National Institute for Applied Statistics Research Australia (NIASRA), School of Mathematics and Applied Statistics, University of Wollongong, Northfields Ave, Wollongong NSW 2522, Australia.
Olivier
O
Thas
D004463:Ecology / Q000379:methods*; D016013:Likelihood Functions; D008962:Models, Theoretical