XVI International Botanical Congess

Chuquiraga is a genus of 23 species of shrubs endemic to the Andes from Colombia to Argentina, that exhibits many leaf morphology types and is especially diversified in deserts and semideserts. Phylogenetic relationships among species are resolved by parsimony cladistic analysis using morphological characters. Optimization of geographical distribution on the inferred phylogeny suggests that the genus evolved in elevated or semielevated regions of temperate southern South America and later radiated to the warmer and tropical regions of the Andes, a secondary diversification center. The genus can be considered 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 also appear to have been important in its evolution.