Quantitative Methods and Biogeographic Analysis

Abstract

Numerical methods are presented that represent three different approaches to biogeographic problems. The first approach is multivariate data analysis. The delineation of biogeographic "provinces" or areas is a type of descriptive analysis that can be accomplished by clustering faunal data (with or without spatial contiguity constraint) and drawing the resulting choropleth map. On the other hand, ecological biogeographers like to use ordinations of sampling localities and interpret the main axes of variation in terms of environmental gradients; canonical ordination, where a species presence or abundance data table and an environmental data matrix are both analyzed simultaneously, can be used with profit in this context. Secondly, the analysis of spatial patterns can help identify the type of spatial distribution of the biological material, both at the population and at the community level, while Mantel tests and other derived analyses make it possible to test hypotheses concerning causal factors possibly responsible for the observed spatial structures. Finally, phylogenetic-tree reconstruction methods, as well as other techniques, can be used for historical biogeographic studies; these include the study of taxa cladograms and of area cladograms