Data from: Water availability and evolutionary similarity shape the global distribution of ferns with chlorophyllous spores

About 14% of all fern species have chlorophyllous spores, which lack
dormancy, have thin walls, and have a shorter viability (only a few days
in some species). These spores should have limited dispersal distances and
be more susceptible to harsher climatic conditions, raising questions
about the evolutionary and ecological significance of this trait. Here, we
assemble the global distribution of chlorophyllous-spored ferns and assess
the underlying environmental and evolutionary factors. We first evaluated
the environmental predictors of the proportional representation of 1387
chlorophyllous-spored species (CSS) across 577 geographical regions using
generalized linear mixed models. We then estimated the phylogenetic signal
of spore type and assessed the relative importance of environmental
factors in the phylogenetic structure of fern assemblages. Species
richness of CSS peaked in the tropics, while their proportional
representation was highest in temperate and island floras. The proportion
of CSS was positively associated with water availability and less seasonal
climates. Spore type was strongly conserved phylogenetically, and CSS
assemblages were phylogenetically clustered towards higher latitudes. Our
study provides strong evidence that chlorophyllous spores do not limit the
geographical distribution of fern species and that their latitudinal
distribution patterns can be explained by a combination of environmental
and evolutionary factors.