Analysis of relative abundances with zeros on environmental gradients: a multinomial regression model

PeerJ

article

Fiona Chong¹  Matthew Spencer² 

[1] Systems Ecology and Resource Management Research Unit, Université Libre de Bruxelles;School of Environmental Sciences, University of Liverpool

关键词: Compositional data analysis;    Fouling communities;    Environmental gradients;    Linear algebra;   

DOI  :  10.7717/peerj.5643

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Ecologists often analyze relative abundances, which are an example of compositional data. However, they have made surprisingly little use of recent advances in the field of compositional data analysis. Compositions form a vector space in which addition and scalar multiplication are replaced by operations known as perturbation and powering. This algebraic structure makes it easy to understand how relative abundances change along environmental gradients. We illustrate this with an analysis of changes in hard-substrate marine communities along a depth gradient. We fit a quadratic multivariate regression model with multinomial observations to point count data obtained from video transects. As well as being an appropriate observation model in this case, the multinomial deals with the problem of zeros, which often makes compositional data analysis difficult. We show how the algebra of compositions can be used to understand patterns in dissimilarity. We use the calculus of simplex-valued functions to estimate rates of change, and to summarize the structure of the community over a vertical slice. We discuss the benefits of the compositional approach in the interpretation and visualization of relative abundance data.

【 授权许可】

CC BY