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Hipp, Andrew
Denk, Thomas
Grimm, Guido
Manos, Paul S.
Deng, Min

Oaks Physiological Ecology. Exploring the Functional Diversity of Genus Quercus L.

Date created
In this chapter, we review major classification schemes proposed for oaks by John Claudius Loudon, Anders Sandøe Ørsted, William Trelease, Otto Karl Anton Schwarz, Aimée Antoinette Camus, Yuri Leonárdovich Menitsky, and Kevin C.Nixon. Classifications of oaks (Fig.2.1) have thus far been based entirely on morphological characters. They differed profoundly from each other because each taxonomist gave a different weight to distinguishing characters; often characters that are homoplastic in oaks. With the advent of molecular phylogenetics our view has considerably changed. One of the most profound changes has been the realization that the traditional split between the East Asian subtropical to tropical subgenus Cyclobalanopsis and the subgenus Quercus that includes all other oaks is artificial.The traditional concept has been replaced by that of two major clades, each comprising three infrageneric groups: a Palearctic-Indomalayan clade including GroupIlex (Ilex oaks), Group Cerris (Cerris oaks) and Group Cyclobalanopsis (cycle-cupoaks), and a predominantly Nearctic clade including Group Protobalanus (interme-diate or golden cup oaks), Group Lobatae (red oaks) and Group Quercus (white oaks, with most species in America and some 30 species in Eurasia). In addition, recent phylogenetic studies identified two distinct clades within a wider group of white oaks: the Virentes oaks of North America and a clade with two disjunct endemic species in western Eurasia and western North America,Quercus pontica and Q. sadleriana. The main morphological feature characterizing these phylogenetic lineages is pollen morphology, a character overlooked in traditional classifications. This realization,along with the now available (molecular-) phylogenetic framework, opens new avenues for biogeographic, ecological and evolutionary studies and a re-appraisal of the fossil record. We provide an overview about recent advances in thesefields andoutline how the results of these studies contribute to the establishment of a unifying systematic scheme of oaks. Ultimately, we propose an updated classification of Quercus recognizing two subgenera with eight sections. This classification considers morphological traits, molecular-phylogenetic relationships, and the evolutionary history of one of the most important temperate woody plant genera.
978-3-319-69098-8, 978-3-319-69099-5
Alternate Title
Chapter 2: An Updated Infrageneric Classification of the Oaks: Review of Previous Taxonomic Schemes and Synthesis of Evolutionary Patterns
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