Dispersal and Regional Diversification Reveal Tropical Mountain Systems as Cradles of Diversification for the Forking Ferns (Gleicheniaceae, Polypodiopsida)
Lucas Vieira Lima, Alexandre Salino, Michael Kessler, Germinal Rouhan, Weston Testo, André Luís de Gasper, Thaís Elias AlmeidaABSTRACT
Aim
To reconstruct the historical biogeography and diversification dynamics of the fern family Gleicheniaceae, testing whether (1) its main centres of diversity are the result of within‐area speciation or lineage immigration, (2) dispersal shows directionality across tropical regions and (3) shifts in geographic distribution are correlated with diversification rates.
Location
Tropical and subtropical regions worldwide, with a focus on tropical America and Southeast Asia.
Taxon
Fern family Gleicheniaceae (Polypodiopsida).
Methods
We used a time‐calibrated phylogeny of Gleicheniaceae combined with ancestral range reconstruction in BioGeoBEARS. Stochastic biogeographic mapping was used to estimate the frequency and directionality of biogeographic events. Diversification dynamics were evaluated using both constant‐rate (Yule and Birth–Death) and rate‐variable (BAMM) approaches, and their relationship with dispersal frequency was examined.
Results
Dispersal was consistently recovered as the predominant process shaping the distribution of Gleicheniaceae under the best‐fitting BAYAREALIKE+J model. Among dispersal‐related processes, range expansion was the most frequent biogeographic event, particularly between the Andes and Brazil, and between Asia and Oceania. Founder‐event dispersal contributed secondarily, enabling long‐distance colonisation. Within‐area cladogenetic events were also frequent, especially in Sticherus . Diversification rates varied across clades: Sticherus and Dicranopteris showed the highest net diversification, coinciding with Neogene peaks in dispersal and climatic changes, whereas geographically restricted genera ( Rouxopteris , Stromatopteris ) exhibited the lowest diversification rates.
Main Conclusions
The evolutionary history of Gleicheniaceae was dominated by dispersal, with the Andes and Asia representing important centres of lineage accumulation and redistribution within their respective regions. Dispersal directionality and its correlation with diversification highlight tropical montane systems as key drivers of lineage radiation. Although complementary analyses indicate that historical geographic isolation may also have contributed to deep divergences, the overall biogeographic pattern remained dominated by dispersal in this ancient fern lineage.