# Global Diversification Rates of Ferns Across Spatial and Climatic Gradients

## TL;DR

This study shows that ferns diversify most in tropical, humid regions and that diversification rates vary with climate and geography.

## Contribution

The paper reveals region-specific diversification drivers and highlights the importance of current climate over historical factors in shaping fern diversity.

## Key findings

- Fern diversification rates are highest in tropical and humid environments.
- Diversification is more influenced by precipitation than temperature and varies across longitudinal regions.
- High species density in ferns is linked to current diversification rates rather than climate alone.

## Abstract

Geographic patterns of diversity in any group of plants are the result of the interplay of environmental conditions and the evolutionary dynamics of the respective plant group. Here, the geographic distribution of current mean diversification rates (MDR) is explored at the genus level for ferns and relate it to climatic conditions and regional species richness. It is found that MDR is highest at tropical latitudes and in humid and hot environments, and is influenced primarily by current climate (rather than historical climate change), by precipitation‐related variables (rather than temperature‐related ones), and roughly equally by climate extremes and seasonality. Furthermore, a positive relationship between MDR and fern species density is found, with the latter being more strongly directly influenced by MDR than by climate, and all of the above‐mentioned patterns differ among longitudinal segments. Critically, the relationship between MDR and climate shifts across longitude, revealing region‐specific diversification drivers. This study shows that diversification rates provide complementary information on the evolutionary history of ferns compared to species richness and phylogenetic diversity, and that highly diverse regional fern assemblages appear to be centers of ferns belonging to rapidly diversifying lineages.

Diversification rates of fern genera across the phylogeny.