The legacy of the paleotropical flora belt: extreme continental vicariance and island refugia in Woodwardioid ferns

Abstract

The distribution of vegetation across the Northern Hemisphere has been profoundly shaped by the climatic and geological history of the Cenozoic. An ancient paleotropical vegetation belt, once spanning the Northern Hemisphere, is hypothesized to have facilitated biotic exchange across regions during the early Cenozoic, before its eventual fragmentation and near-complete disappearance. This study investigates the evolutionary history of this pattern using the fern subfamily Woodwardioideae (Blechnaceae)—a striking example of disjunction across the Northern Hemisphere.