Niche evolution in a northern temperate tree lineage: biogeographic legacies in cork oaks (Quercus sect. Cerris)

Thomas Denk, G.W. Grimm, Andrew L Hipp, Johannes M Bouchal, Ernst-Detlef Schulze, Marco C Simeone

Cork oaks (Quercus sect. Cerris) comprise 15 extant species in Eurasia. Despite being a small clade, they display a range of leaf morphologies comparable to the largest sections (\gt;100 spp.) in Quercus. Their fossil record extends back to the Eocene. Here, we explore how cork oaks achieved their modern ranges and how legacy effects may explain niche evolution in modern species of section Cerris and its sister section Ilex, the holly oaks.We inferred a dated phylogeny for cork and holly oaks using a reduced-representation next-generation sequencing method, restriction-site associated DNA sequencing (RAD-seq) and used D-statistics to investigate gene flow hypotheses. We estimated divergence times using a fossilized birth-death (FBD) model calibrated with 47 fossils. We used Köppen profiles, selected bioclimatic parameters, and forest biomes occupied by modern species to infer ancestral climatic and biotic niches.East Asian and Western Eurasian cork oaks diverged initially in the Eocene. Subsequently, four Western Eurasian lineages (subsections) differentiated during the Oligocene and Miocene. Evolution of leaf size, form, and texture partly correlates with multiple transitions from ancestral humid temperate climates to Mediterranean, arid, and continental climates. Distantly related but ecologically similar species converged on similar leaf traits in the process.Originating in temperate (frost-free) biomes, Eocene to Oligocene ranges of the primarily deciduous cork oaks were restricted to higher latitudes (Siberia to north of Paratethys). Members of the evergreen holly oaks (sect. Ilex) also originated in temperate biomes but migrated south- and south-westwards into then-(sub)tropical southern China and south-eastern Tibet during the Eocene, then westwards along existing pre-Himalayan mountain ranges. Divergent biogeographic histories and deep-time phylogenetic legacies—in cold and drought tolerance, nutrient storage, and fire resistance—thus account for the modern species mosaic of Western Eurasian oak communities, which comprise oaks belonging to four sections.

Department für Botanik und Biodiversitätsforschung
Externe Organisation(en)
Swedish Museum of Natural History
Annals of Botany
Anzahl der Seiten
ÖFOS 2012
105117 Paläobotanik, 106008 Botanik
ASJC Scopus Sachgebiete
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