title: Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests.
abstract: The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data.
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Stuttgart, Germany; Dept. Biodiversity und Plant Systematics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Paulina
authors.initials: P
authors.lastname: Kondraskov
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Stuttgart, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Schütz
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Stuttgart, Germany; Dept. Biodiversity und Plant Systematics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Schüßler
authors.affiliation: Universidade da Madeira, Centro de Ciências da Vida, Funchal, Madeira, Portugal.
authors.forename: Miguel Menezes
authors.initials: MM
authors.lastname: de Sequeira
authors.affiliation: Unidad de Botánico (ICIA), Puerto de la Cruz, Tenerife, Spain.
authors.forename: Arnoldo Santos
authors.initials: AS
authors.lastname: Guerra
authors.affiliation: Jardin Botanico Canario "Viera y Clavijo"-Unidad Asociada CSIC, Las Palmas de Gran Canaria, Spain.
authors.forename: Juli
authors.initials: J
authors.lastname: Caujapé-Castells
authors.affiliation: Jardin Botanico Canario "Viera y Clavijo"-Unidad Asociada CSIC, Las Palmas de Gran Canaria, Spain.
authors.forename: Ruth
authors.initials: R
authors.lastname: Jaén-Molina
authors.affiliation: Jardin Botanico Canario "Viera y Clavijo"-Unidad Asociada CSIC, Las Palmas de Gran Canaria, Spain.
authors.forename: Águedo
authors.initials: Á
authors.lastname: Marrero-Rodríguez
authors.affiliation: Dept. Biodiversity und Plant Systematics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Marcus A
authors.initials: MA
authors.lastname: Koch
authors.affiliation: Institute of Systematic Botany, University of Zurich, Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Linder
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Stuttgart, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Kovar-Eder
authors.affiliation: Botany Department, State Museum of Natural History Stuttgart, Stuttgart, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Thiv
mesh_terms: D044822:Biodiversity; D065928:Forests; D019083:Mediterranean Region; D058974:Phylogeography; D014197:Trees / Q000145:classification