XVI International Botanical Congess

The Juan Fernández Archipelago has undergone dramatic geological, physical, phylogenetic, populational, and anthropogenic evolution. It is a good system in which to address evolutionary and biogeographic questions because there are only two major islands (Masatierra and Masafuera), they have different radiometric dates (4 and 1-2 million years old), they occur in a west-east orientation, the island closest to the continent (and major source area) is older, and the flora is small (127 endemic vascular plants). Our investigations over the past two decades have revealed a near absence of chromosomal variation, low levels of isozyme variability, dominance of phyletic evolution during speciation stimulated by geographic isolation, limitations of simple biogeographic models, varying degrees of phylogenetic sequence divergence from suspected progenitors, and phytogeographic patterns from the predictable to the unexpected.