ibclogo XVI International Botanical Congess


Abstract Number: 4269
Poster No. = 373


PHYLOGENY, LEAF MORPHOLOGY AND BIOGEOGRAPHY OF CHUQUIRAGA (ASTERACEAE, BARNADESIOIDEAE)


Cecilia Ezcurra (CRUB, Universidad Nacional del Comahue, Bariloche, Argentina)


Chuquiraga is a genus of 23 species of xeromorphic shrubs endemic to South America, distributed along the Andes from Colombia to Argentina. This genus exhibits many leaf morphology types and is especially diversified in deserts and semideserts. Phylogenetic relationships among its species are resolved by parsimony cladistic analysis using morphological characters. Optimization of geographical distribution on the inferred phylogeny suggests that the genus evolved in temperate southern South America and later radiated to the warmer Monte, Prepuna and Chilean deserts, and to the tropical Andes, a secondary diversification center for the genus. Therefore Chuquiraga can be considered a genus of Austral origin whose radiation was probably related to the climatic changes associated to the major elevation of the Andes in late Tertiary, and to the hyperaridization and climatic fluctuations of Quaternary. Biotic factors such as the selective pressure of herbivores and shift in pollinator type also appear to have been important in the evolution of this genus.


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