title: Diversity hotspots of the laurel forest on Tenerife, Canary Islands: a phylogeographic study of Laurus and Ixanthus.
abstract: Macaronesian laurel forest is among the worldwide hotspots of threatened biodiversity. With increasing evidence that woodland composition on the Canary Islands changed dramatically during the last few thousand years, the aim of this study was to find evidence for substantial recent population dynamics of two representative species from laurel forest.
  
  
  
  Amplified fragment length polymorphism (AFLP) was used to evaluate fine-scaled genetic variation of the paradigmatic tree Laurus novocanariensis (Lauraceae) and a long-lived herbaceous gentian from core laurel forest, Ixanthus viscosus (Gentianaceae), on Tenerife. Bioclimatic variables were analysed to study the respective climate niches. A chloroplast DNA screening was performed to evaluate additional genetic variation.
  
  
  
  Genetic diversity of the laurel tree showed severe geographic partitioning. On Tenerife, fine-scaled Bayesian clustering of genetic variation revealed a western and an eastern gene pool, separated by a zone of high admixture and with a third major gene pool. Compared with genetic clusters found on the other Canary Islands, the East-West differentiation on Tenerife seems to be more recent than differentiation between islands. This is substantiated by the finding of extremly low levels of chloroplast DNA-based polymorphisms. Ixanthus showed no geographic structuring of genetic variation.
  
  
  
  Genetic data from Tenerife indicate contemporary gene flow and dispersal on a micro/local scale rather than reflecting an old and relic woodland history. In particular for Laurus, it is shown that this species occupies a broad bioclimatic niche. This is not correlated with its respective distribution of genetic variation, therefore indicating its large potential for contemporary rapid and effective colonization. Ixanthus is more specialized to humid conditions and is mostly found in the natural Monteverde húmedo vegetation types, but even for this species indications for long-term persistence in the respective bioclimatically differentiated regions was not find.
authors.affiliation: Department of Plant Systematics and Biodiversity, Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Betzin
authors.affiliation: Department of Botany/Herbarium STU, Staatliches Museum für Naturkunde Stuttgart, D-70191 Stuttgart, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Thiv
authors.affiliation: Department of Plant Systematics and Biodiversity, Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, D-69120 Heidelberg, Germany Heidelberg Centre for the Environment (HCE), Heidelberg University, D-69120 Heidelberg, Germany marcus.koch@cos.uni-heidelberg.de.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Koch
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001499:Bayes Theorem; D018742:DNA, Chloroplast / Q000235:genetics; D065928:Forests; D051456:Gene Flow; D014644:Genetic Variation; D029965:Gentianaceae / Q000235:genetics*; D027442:Laurus / Q000235:genetics*; D058974:Phylogeography; D011110:Polymorphism, Genetic; D013030:Spain
chemical_list: D018742:DNA, Chloroplast
keywords: Canary Islands; Ixanthus viscosus; Laurus novocanariensis; genetic diversity; hotspots; laurel forest