Talk, Annual Conference of the Society for Tropical Ecology (Gesellschaft für Tropenökologie, gtö), Friedrich-Alexander-University Erlangen-Nürnberg: 2012-02-22 - 2012-02-25
The genus Aeonium WEBB & BERTHEL. serves as popular example for adaptive radiation on islands within the plant kingdom. In a relatively short evolutionary period various ecological niches have been realized and a great variety of morphological forms and ecophysiological characteristics have developed. The Canary Islands are the distinct centre of species diversity within that genus and recent research results imply a phylogenetic origin on that volcanic archipelago, stating Aeonium as neoendemic. Most of the species occur only on single islands and clear intrageneric lineages with vicariant island distributions can be seen, which, with respect to the young geological age of some of the Canary Islands and further hints, indicates recent speciation and ongoing evolutionary processes. Considering phylogenetic and biogeographical relationships we selected three ecologically different single island endemic Aeonium species of La Palma, Tenerife and El Hierro and one variety distributed across two of these islands to identify and compare population structures, potential evolutionary relevant differentiations and gene flow barriers. By taking into account the strong topographical and ecological heterogeneity as well as the steep elevational and environmental gradients of these geologically young and highly structured islands we hypothesize distinct intraspecific genetic patterns according to these structures over different geographical scales and differences among our study species. From each taxon DNA-samples comprehensively were taken throughout the respective entire distribution range and DNA fingerprinting data were collected by analysing 10 ISSR (Inter Simple Sequence Repeats) markers, respectively. Population genetic analyses combined with GIS studies are being carried out to detect geographically and ecologically conditioned population differentiations in order to investigate biogeographical structures and evolutionary processes within these island endemics.