Data from: WHAT DOES FUNCTIONAL DIVERSITY AND PHYLOGENETIC SIGNAL REVEAL ABOUT SOUTHERN BRAZILIAN TERRESTRIAL FERNS' ENVIRONMENTAL PREFERENCES?

Questions: Our study focuses on the following questions: 1) Do the climatic and edaphic conditions of the Southern Brazilian Atlantic Forest impact terrestrial ferns' functional diversity? 2) Which morphological functional traits are most relevant for terrestrial ferns in response to climatic and edaphic changes? 3) If there are trait-environment relationships, what adaptive eco-evolutionary mechanisms can be inferred from them? Study site: Subtropical Atlantic Forest, encompassing Rio Grande do Sul, Santa Catarina, and Paraná States, Brazil. Method: We analyzed eleven morphological traits related to resistance, competitive advantage, and reproductive success. All traits were analyzed with and without phylogenetic correction to compute multi-trait functional diversity using the standardized effect size of mean functional distance and functional composition via the community-weighted mean. Both metrics were weighted by the absolute frequency of species within sites. Subsequently, we identified the most influential climatic or edaphic drivers based on linear models. To assess the significance of trait-environment relationships, we employed a permutational approach. Results: The functional diversity of terrestrial ferns correlates with rainfall and temperature, with subtle changes when taking into account the phylogenetic relationship of species. Similarly, competitive and reproductive traits were associated with annual rainfall and rainfall seasonality. However, most morphological traits vary independently of edaphic and climatic factors, regardless of whether phylogenetic relatedness is considered or not. Few traits, specifically related to resistance and competition, were dispersed across the phylogeny and were not linked with any factor evaluated, leaving the question of their true determinants unanswered. Conclusions: Combining functional and phylogenetic information on terrestrial ferns indicates that species morphology response highly depends on the scale observed. Our analyses demonstrate that climatic and not edaphic factors are the primary drivers of trait diversity in terrestrial ferns within the Subtropical Atlantic Forest, influencing most evaluated traits. These findings may help predict the distribution of terrestrial ferns amidst the increasing trend of land use and cover changes in the Atlantic Forest domain.