Biogeographical patterns observed in floras are the result of a number of historical factors. Biogeographers have viewed tectonic events as significant historical factors influencing patterns of species richness, endemism, and biotic history based on phylogenetic analyses. In many cases, biogeographers consider tectonic events in the context of major plate movements resulting in continental separation, convergence and generalized orogenic events. Other phenomena associated with major plate movements, as well as motions of smaller "microplates", have also had a considerable impact on the evolution of major groups and development of biota. In particular, plant evolution and floras of South America have been strongly influenced by tectonic events on several scales. Microplate movements have played a significant role in the continental evolution of both the northern and southern margins of the continent. Hot spots and their associated aseismic ridges have also influenced the development of floras on both the eastern and western margins of South America. Finally, recent studies have indicated that the main Andean deformation consisted of a series of events starting in the Jurassic (Andes of Columbia-Ecuador) and continuing into the present. These events have resulted in segmenting the 9000 km mountain range into seven sections. Each section has a distinct orogenic history of its own. The potential impact of these events on biota was examined using both distribution data and phylogenies of selected angiosperm groups. Although we think of the evolution of older groups being influenced by tectonics, younger families (e.g. Asteraceae and Calyceraceae) also have histories tied with tectonic events.

Key words: Biogeography, Phytogeography, South America, Tectonics