Shaded habitats drive higher rates of fern diversification

Modern ferns diversified simultaneously with the rise of angiosperms. This
pattern is arguably the consequence of ecological opportunities presented
by shady and moist habitats that emerged with the advent of angiosperm
dominated habitats. This hypothesis was tested by applying
phylogenetic comparative methods that investigated the role of shaded
habitats in fern diversification across 1397 fern species from 37
families. Our results showed a significant positive correlation
between the occupancy of shaded habitats and diversification rates across
the phylogeny of ferns compared to those of open habitats with high
sunlight. Tests evaluating false correlations using hidden state
speciation and extinction corroborated this result. Since the onset of the
Angiosperm Terrestrial Revolution, the diversification rates of
shade-dwelling ferns has exceeded those of sun-dwelling ferns. Synthesis:
Our findings support the hypothesis that shaded habitats created by the
flourishing of angiosperms resulted in the acceleration of fern
diversification as a consequence of the successful colonization of shaded
moist habitats in angiosperm dominated forests.