How to be a big genus? Ficus L. as an emerging model

If we replayed the tape of life, would large lineages evolve into the same dazzling diversity observed today? While the macroevolutionary drivers underlying plant diversification have been investigated for some large genera, many clades remain understudied. Ficus L., with 876 species, one of the largest and most ecologically important genera in Moraceae, is renowned for its iconic inflorescence, intricate pollination mutualism, and broad ecological adaptability. As the sole member of the monotypic tribe Ficeae, Ficus occupies a unique evolutionary position within a family that also includes major crop plants such as common fig, breadfruit, breadnut, cempedak, jackfruit, che, and mulberries.

We used a well-sampled, dated phylogenomic backbone of Moraceae to investigate diversification patterns and their associated drivers in Ficus and allied genera using Maximum-Likelihood and Bayesian process-based methods. We assembled a morphological matrix of 508 species in Moraceae to investigate patterns of trait evolution based on stochastic mapping.

Our results indicate that diversification within Moraceae is closely associated with shifts in global paleoclimate. The emergence of key clades of pollen and seed dispersers during periods of global warming following the Cretaceous-Paleogene (K-Pg) boundary approximately 66 Mya appears to have significantly shaped the complex diversification patterns observed in Ficus. Evolutionary transitions in floral traits within Moraceae are linked to changes in pollinator guilds; however, HiSSE (Hidden State Speciation and Extinction) models suggest that these shifts alone may not fully account for the diversification dyanmics of the genus.

This study advances our understanding of the drivers of diversification in big pantropical genera, emphasizing the need to integrate multiple lines of evidence to holistically reconstruct the evolutionary history of ecologically and morphologically diverse plant taxa.