Trait-dependent biogeography offers insights on the dispersal of Meiogyne (Annonaceae) across the Australasia-Pacific region

Abstract

Meiogyne is a genus of trees and treelets occurring in Indomalaya and Australasia-Pacific, an unusually wide distribution across Australasia and Western Pacific compared to the rest of the family Annonaceae. Previous chloroplast phylogenies of the genus offered poor resolution and support for many internal nodes. Here, a molecular phylogeny was reconstructed based on seven chloroplast and 11 nuclear markers of 33 Meiogyne taxa (ca. 70% sampling). The combined dataset generated a well resolved and supported phylogeny. Estimation of divergence time was calibrated with two fossils using uncorrelated lognormal relaxed clock model. Trait-dependent and trait-independent biogeographical models in BioGeoBEARS were compared using AICc weight and likelihood ratio test. The results suggest that narrow monocarp width and fruit colour associated with bird dispersal are correlated with increased macroevolutionary dispersal. Under the best-fitting monocarp width-dependent DEC model, a single colonisation event from Sunda to Sahul during the middle to late Miocene and two dispersal events from New Guinea and Australia into the Pacific during the late Miocene to early Pliocene were detected. BayesTraits analysis strongly supports a correlation between narrow fruits and avian fruit colours. This study reveals that Meiogyne lineages with narrow fruitlets and fruit colour associated to bird dispersal (black, red & orange) are associated with increased macroevolutionary dispersal. Bird dispersal and the associated traits may be important drivers for macroevolutionary dispersal for plants with fleshy fruits in Australasia-Pacific.