Historical reconstruction of climatic and elevation preferences and the evolution of cloud forest-adapted tree ferns in Mesoamerica

Background. Cloud forest, characterized by a persistent, frequent or seasonal low-level cloud cover and a fragmented distribution, is one of the most threatened habitats especially in the Neotropics. Tree ferns are among the most conspicuous elements in these forests and ferns are restricted to regions in which minimum temperatures rarely drop below freezing and rainfall is high and evenly distributed around the year. Current phylogeographic data suggest that some of the cloud forest-adapted species remained in situ or expanded to the lowlands during glacial cycles and contracted allopatrically during the interglacials. Although the observed genetic signals of population size changes of cloud forest-adapted species including tree ferns correspond to predicted changes by Pleistocene climate change dynamics, the observed patterns of intraspecific lineage divergence showed temporal incongruence.

Methods. Here we combined phylogenetic analyses, ancestral area reconstruction, and divergen...