Spatial analysis of taxonomic and genetic patterns and their potential for understanding evolutionary histories

• Published in: Journal of biogeography 2004-11, Vol.31 (11), p.1715-1733
• Main Authors: Bickford, Sophia A., Laffan, Shawn W., de Kok, Rogier P. J., Orthia, Lindy A.
• Format: Article
• Language: English
• Subjects: A Touch of Theory; Animal and plant ecology; Animal, plant and microbial ecology; Biogeography; Biological and medical sciences; Biological taxonomies; biotic elements; diversity pattern; endemism; Evolution; Evolutionary genetics; Fabaceae; Fundamental and applied biological sciences. Psychology; General aspects; Genetic diversity; Geographic regions; macro-evolutionary processes; Phylogenetics; Pultenaea; Spatial analysis; Speciation; Species diversity; Synecology; Taxa
• ISSN: 0305-0270; 1365-2699
• DOI: 10.1111/j.1365-2699.2004.01127.x

Aim The aim of this research is to develop and investigate methods for the spatial analysis of diversity based on genetic and taxonomic units of difference. We use monophyletic groups of species to assess the potential for these diversity indices to elucidate the geographical components of macro-scaled evolutionary processes. Location The range occupied by Pultenaea species in temperate and sub-tropical eastern Australia, extending from western South Australia (133° E-32° S) to Tasmania (146° E-43° S) to coastal central Queensland (148° E-20° S). Methods We applied a series of both spatially explicit and spatially implicit analyses to explore the nature of diversity patterns in the genus Pultenaea, Fabaceae. We first analysed the eastern species as a whole and then the phylogenetic groups within them. We delineated patterns of endemism and biotic (taxon) regions that have been traditionally circumscribed in biogeographical studies of taxa. Centres of endemism were calculated using corrected weighted endemism at a range of spatial scales. Biotic regions were defined by comparing the similarity of species assemblages of grid cells using the Jaccard index and clustering similar cells using hierarchical clustering. On the basis that genetically coherent areas were likely to be more evolutionary informative than species patterns, genetic indices of similarity and difference were derived. A matrix of similarity distances between taxa was generated based on the number of shared informative characters of two sections of trnL-F and ndhF chloroplast nuclear regions. To identify genetically similar areas, we clustered cells using the mean genetic similarities of the species contained within each pair of cells. Measures of the mean genetic similarity of species in areas were delineated using a geographically local multi-scalar approach. Resultant patterns of genetic diversity are interpreted in relation to theories of the evolutionary relationships between species and species groups. Results Centres of Pultenaea endemism were defined, those of clades 1 congruent with the spatially separated centres of clades 2 and 3. The taxonomic classification analysis defined cells with shared groups of species, which in some cases clustered when plotted in geographic space, defining biotic regions. In some instances the distribution of biotic regions was congruent with centres of endemism, however larger scale groupings were also apparent. In clade 1 one set of species was replace