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2018 | Buch

Numerical Ecology with R

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This new edition of Numerical Ecology with R guides readers through an applied exploration of the major methods of multivariate data analysis, as seen through the eyes of three ecologists. It provides a bridge between a textbook of numerical ecology and the implementation of this discipline in the R language. The book begins by examining some exploratory approaches. It proceeds logically with the construction of the key building blocks of most methods, i.e. association measures and matrices, and then submits example data to three families of approaches: clustering, ordination and canonical ordination. The last two chapters make use of these methods to explore important and contemporary issues in ecology: the analysis of spatial structures and of community diversity. The aims of methods thus range from descriptive to explanatory and predictive and encompass a wide variety of approaches that should provide readers with an extensive toolbox that can address a wide palette of questions arising in contemporary multivariate ecological analysis. The second edition of this book features a complete revision to the R code and offers improved procedures and more diverse applications of the major methods. It also highlights important changes in the methods and expands upon topics such as multiple correspondence analysis, principal response curves and co-correspondence analysis. New features include the study of relationships between species traits and the environment, and community diversity analysis.

This book is aimed at professional researchers, practitioners, graduate students and teachers in ecology, environmental science and engineering, and in related fields such as oceanography, molecular ecology, agriculture and soil science, who already have a background in general and multivariate statistics and wish to apply this knowledge to their data using the R language, as well as people willing to accompany their disciplinary learning with practical applications. People from other fields (e.g. geology, geography, paleoecology, phylogenetics, anthropology, the social and education sciences, etc.) may also benefit from the materials presented in this book. Users are invited to use this book as a teaching companion at the computer. All the necessary data files, the scripts used in the chapters, as well as extra R functions and packages written by the authors of the book, are available online (URL: http://adn.biol.umontreal.ca/~numericalecology/numecolR/).

Inhaltsverzeichnis

Frontmatter
Chapter 1. Introduction
Abstract
This chapter explains the importance of numerical ecology as well as the interest of using R in this field. It exposes the structure of the book and presents the main data sets used in the applications. Links to the datasets and R scripts are provided. This chapter also explains how to use the book for maximum efficiency.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 2. Exploratory Data Analysis
Abstract
Nowadays, most ecological research is done with hypothesis testing and modelling in mind. However, Exploratory Data Analysis (EDA), with its visualization tools and simple statistics, is still required at the beginning of the statistical analysis of multidimensional data, in order to get an overview of the data, transform or recode some variables or orient further analyses. In this chapter you will learn or revise some bases of the R language, learn some EDA techniques that are frequently applied to multidimensional ecological data and explore the Doubs dataset in hydrobiology as a first worked example, using R functions mostly found in standard packages.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 3. Association Measures and Matrices
Abstract
Most methods of multivariate analysis, in particular ordination and clustering techniques, are explicitly or implicitly based on the comparison of all possible pairs of objects or descriptors. The comparisons take the form of association measures (often called coefficients or indices), which are assembled in a square and symmetric association matrix, of dimensions n × n when objects are compared, or p × p when variables are compared. Since the subsequent analyses are done on association matrices, the choice of an appropriate measure is crucial. In this Chapter you will quickly revise the main categories of association coefficients, learn how to compute, examine and visually compare dissimilarity matrices (Q mode) and dependence matrices (R mode), apply these techniques to a classical dataset and learn or revise some basics of programming functions with the R language.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 4. Cluster Analysis
Abstract
In most cases, data exploration and the computation of association matrices are preliminary steps towards deeper analyses. In this chapter you will go further by experimenting one of the large groups of analytical methods used in ecology: clustering. Practically, you will learn how to choose among various clustering methods and compute them, apply these techniques to the Doubs River data to identify groups of sites and fish species. You will also explore two methods of constrained clustering, a powerful modelling approach where the clustering process is constrained by an external data set.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 5. Unconstrained Ordination
Abstract
Ordination extracts the main trends in the form of continuous axes. It is therefore particularly well adapted to analyse data from natural ecological communities, which are generally structured in gradients. In this chapter, you will learn how to choose among various ordination techniques (PCA, CA, MCA, PCoA and NMDS), compute them using the correct options, and properly interpret the ordination diagrams; apply these techniques to the Doubs River or the Oribatid mite data; overlay the result of a cluster analysis on an ordination diagram to improve the interpretation of both analyses; interpret the structures revealed by the ordination of the species data using the environmental variables from a second dataset; and finally write your own PCA function.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 6. Canonical Ordination
Abstract
Canonical ordination associates two or more data sets in the ordination process itself. Consequently, if one wishes to extract structures of a data set that are related to (or can be interpreted by) another data set, and/or formally test statistical hypotheses about the significance of these relationships, canonical ordination is the way to go. in this chapter, you will learn how to choose among various canonical ordination techniques: asymmetric (RDA, db-RDA, CCA, LDA, PRC and CoCA) and symmetric (CCorA, CoIA and MFA); explore methods devoted to the study of the relationships between species traits and environment; compute them using the correct options and properly interpret the results; apply these techniques to the Doubs River and other data sets; explore particular applications of some canonical ordination methods, for instance variation partitioning and multivariate analysis of variance by RDA; and write your own RDA function.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 7. Spatial Analysis of Ecological Data
Abstract
The present chapter deals with methods developed for the analysis of scale-dependent structures of ecological data. These methods are based on sets of variables describing spatial structures derived from the coordinates of the sites or from the neighbourhood relationships among sites. These variables are used to model the spatial structures of ecological data by means of multiple regression or canonical ordination, and to identify significant spatial structures at all spatial scales that can be perceived by the sampling design. Practically, you will learn how to compute spatial correlation measures and draw spatial correlograms; learn how to construct spatial descriptors derived from site coordinates and from links between sites; identify, test and interpret scale-dependent spatial structures; combine spatial analysis and variation partitioning; and assess spatial structures in canonical ordinations by computing variograms of explained and residual ordination scores.
Daniel Borcard, François Gillet, Pierre Legendre
Chapter 8. Community Diversity
Abstract
In many people’s minds, the words “diversity” or “biodiversity” simply refer to the number of species in a given area, but actually there are far more dimensions to the concept of biodiversity. Species diversity itself can be defined and measured in a variety of ways. Other types of diversity exist at various levels of organization of the living world, ranging from genome to landscape. At the community level, functional diversity, i.e., the diversity of functional traits, has received much attention in recent years, as well as phylogenetic diversity. We will mostly focus here on species and communities and explore first various facets of taxonomic diversity. In this chapter you will get an overview of the concept of diversity in ecology; compute various measures of alpha species diversity; explore the concept of beta diversity; partition beta diversity into its local and species contributions; partition beta diversity into replacement, richness difference and nestedness; and get a brief introduction to the concept of functional diversity.
Daniel Borcard, François Gillet, Pierre Legendre
Backmatter
Metadaten
Titel
Numerical Ecology with R
verfasst von
Daniel Borcard
François Gillet
Pierre Legendre
Copyright-Jahr
2018
Electronic ISBN
978-3-319-71404-2
Print ISBN
978-3-319-71403-5
DOI
https://doi.org/10.1007/978-3-319-71404-2