XVI International Botanical Congess
We assess the floristic affinities of pteridophytes between the Neotropics and Africa-Madagascar and examine how these affinities might have arisen. Two levels of relationship are recognized: 1) shared species between both regions and 2) species pairs. We find 111 examples, of which 27 are same-species and 84 are species pairs. About 20% of the African and 13% of the Madagascan pteridoflora show affinities with the Neotropics. To determine how these similarities arose, we consider three hypotheses: 1) boreotropics hypothesis, 2) continental drift, 3) long-distance dispersal. Nearly all examples seem best explained by long-distance dispersal because they belong to families that first appeared during the Paleocene or later, about 30 million years after drift had effectively separated South America and Africa.