IngentaConnect Biotic Element Analysis in Biogeography

Authors: Hausdorf B.¹; Hennig C.²

Source: Systematic Biology, Volume 52, Number 5, October 2003 , pp. 717-723(7)

Abstract:

Biotic element analysis is an alternative to the areas-of-endemism approach for recognizing the presence or absence of vicariance events in a given region. If an ancestral biota was fragmented by vicariance events, biotic elements or clusters of distribution areas should emerge. We propose a statistical test for clustering of distribution areas based on a Monte Carlo simulation with a null model that considers the spatial autocorrelation in the data. The hypothesis tested is that the observed degree of clustering of ranges can be explained by the range size distribution, the varying number of taxa per cell, and the spatial autocorrelation of the occurrences of a taxon alone. A method for the delimitation of biotic elements which uses model-based Gaussian clustering is introduced. We demonstrate our methods and show the importance of grid size by means of a case study, an analysis of the distribution patterns of southern African species of the weevil genus Scobius. The example highlights the difficulties in delimiting areas of endemism if dispersal has occurred and illustrates the advantages of the biotic element approach.

Keywords: Area of endemism; biogeography; biotic elements; null model; Scobius; South Africa; vicariance

Document Type: Research article

Affiliations: 1: Zoologisches Museum der Universität Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany;, Email: hausdorf@zoologie.uni-hamburg.de 2: ETH Zürich (LEO), Seminar für Statistik, 8092 Zürich, Switzerland; , and Universität Hamburg, Fachbereich Mathematik-SPST, Bundesstrasse 55, 20146 Hamburg, Germany, Email: hennig@stat.math.ethz.ch

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