Ecologically meaningful transformations for ordination of species data.

This paper examines how to obtain species biplots in unconstrained or constrained ordination without resorting to the Euclidean distance [used in principal-component analysis (PCA) and redundancy analysis (RDA)] or the chi-square distance [preserved in correspondence analysis (CA) and canonical correspondence analysis (CCA)] which are not always appropriate for the analysis of community composition data. To achieve this goal, transformations are proposed for species data tables. They allow ecologists to use ordination methods such as PCA and RDA, which are Euclidean-based, for the analysis of community data, while circumventing the problems associated with the Euclidean distance, and avoiding CA and CCA which present problems of their own in some cases.

Competition among the pioneers in a seasonal soft-bottom benthic succession: field experiments and analysis of the Gilpin-Ayala competition model.

Controlled experiments, designed to assess the effects of pioneers on succession on an intertidal sandflat, provided evidence for interspecific competition between juvenile Hobsonia florida (Polychaeta, Ampharetidae) and oligochaetes. The field data were fitted to both the linear Volterra and non-linear Gilpin-Ayala competition equations. With its greater number of parameters, the Gilpin-Ayala model must provide a better fit to observed population abundances.

Antigenic similarities among estuarine soft-bottom benthic taxa.

Antisera prepared against whole-organism extracts of benthic invertebrates from Puget Sound, Washington, and North Inlet, South Carolina, were tested for specificity with extracts from both coasts. Immunological similarities among taxa reflected conventional phylogenetic relationships both within each of these areas and also between both areas. Antisera also cross-reacted with extracts to a lesser degree at higher taxonomic levels.