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Título del libro: Tree Of Life: Evolution And Classification Of Living Organisms
Título del capítulo: Eudicotyledons The Greatest Flower Diversity in Angiosperms

Autores UNAM:
SUSANA AURORA MAGALLON PUEBLA;
Autores externos:

Idioma:

Año de publicación:
2014
Palabras clave:

EUDICOTS


Resumen:

Phylogenies based on morphological characters as well as on DNA sequences have identified a clade within angiosperms (flowering plants) that includes all species that develop tricolpate pollen. This group, named eudicots (eudicotyledons, Eudicotyledoneae), comprises approximately 198,000 species distributed among approximately 10,400 genera, 336 families and 51 orders, and represents more than 73% of living angiosperms. Eudicots are strongly supported as a monophyletic group by all phylogenetic reconstructions, and recent studies suggest that the Ceratophyllales (a small group of aquatic plants) and monocots are the closest angiosperm relatives. The tree of eudicots exhibits six early diverging clades, and a large core clade named Pentapetalae, which includes the vast majority of species. The extensive Pentapetalae group, in turn, is formed by eight clades whose interrelationships are not yet fully understood. Most Pentapetalae members display a flower structure characterized by a bipartite perianth formed by calyx and corolla, and (usually) a fixed number of organs in each whorl: five in the perianth and androecium, and two (or three) in the gynoecium. Phylogenetic studies of neutral and regulatory genes have documented numerous gene duplications apparently associated with Pentapetalae and possibly an entire genome duplication at an early evolutionary stage. Among duplicated genes are members of the MADS-box family, which regulate a variety of key functions and were probably highly involved in the evolution of the bipartite perianth. The fossil record and molecular clock estimates indicate that eudicot diversification had begun by the Early Cretaceous (Barremian-Aptian age, 125 million years ago), while the diversification of Pentapetalae would have begun by at least the Cenomanian (Late Cretaceous, 100-93.5 million years ago).


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