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Media type:
E-Article
Title:
Patterns of molecular and morphological differentiation in Fagus (Fagaceae): phylogenetic implications
Contributor:
Denk, Thomas;
Grimm, Guido W.;
Hemleben, Vera
Published:
Wiley, 2005
Published in:
American Journal of Botany, 92 (2005) 6, Seite 1006-1016
Language:
English
DOI:
10.3732/ajb.92.6.1006
ISSN:
0002-9122;
1537-2197
Origination:
Footnote:
Description:
<jats:p>To study phylogenetic relationships among species of <jats:italic>Fagus</jats:italic>, the internal transcribed spacer regions ITS1 and ITS2 of the nuclear ribosomal DNA and morphological data were analyzed. Both molecular and morphologically based phylogenies suggest that Eurasian species of <jats:italic>Fagus</jats:italic> subgenus <jats:italic>Fagus</jats:italic> are basal to the North American <jats:italic>Fagus grandifolia</jats:italic>. The subgenus <jats:italic>Fagus</jats:italic> is a paraphyletic group basal to three East Asian species forming the subgenus <jats:italic>Engleriana</jats:italic>. Due to a considerably large amount of DNA polymorphism, relationships among basal species of <jats:italic>Fagus</jats:italic> could not be entirely resolved when analyzing ITS sequences with standard methods. Morphological trees helped to resolve more clearly relationships within the subgenus <jats:italic>Fagus</jats:italic>. The East Asian <jats:italic>F. hayatae</jats:italic> is suggested to be basal to the rest of the genus. This hypothesis is further supported by distinctive patterns of nucleotide variability found for ITS regions, allowing for basic and derived types to be distinguished. The high degree of ITS polymorphism within <jats:italic>Fagus</jats:italic> can be explained by (1) the complex evolutionary behavior of this marker, (2) the stenoecious ecological characteristic of <jats:italic>Fagus</jats:italic> with respect to its continuous geographic range throughout much of the Cenozoic, and (3) the absence of major radiations into further habitats as occurred in other Fagaceae.</jats:p>