Processes of evolution in the flora of southern South America
B. B. Simpson1, H. M. Meudt2;
1The University of Texas, Austin, TX, United States, 2Massey University, Palmerston, New Zealand.

Presentation Number: 13.3.1
Keyword: Biogeography, southern South America, dispersal

The flora of southern South America has developed from indigenous elements, taxa that arrived from Australasia, Africa, or North America, as well as neotropical elements that moved into the high latitudes. The timing of the establishment of non-native taxa depended on the development of suitable habitats. Likewise radiations of non-native and indigenous taxa depended on the shifting patterns of geology and climate that determined the temporal and spatial patterns of the habitats we now see in southern South America. The relative importance of vicariance and dispersal as the factor determining the influx of taxa depended on habitat and to some extent life history. Recent molecular phylogenetic studies have shown that many of the elements in the southern flora are the result of radiations of native stocks but for herbaceous and shrubby taxa shared with Australasia, Africa, and North America, long-distance dispersal appears to have been the dominant mode of movement between areas.