Phylogeny and biogeography of the Cryptocaryeae (Lauraceae)

Abstract

AbstractThe biogeographical history of many lineages within the Lauraceae remains poorly known because of the difficulty of assigning macrofossils to living genera, poor pollen preservation, and the absence of sufficiently resolved or well‐supported phylogenies. Here, we utilize plastid genome sequencing to reinvestigate the phylogenetic and biogeographic history of trees in the tribe Cryptocaryeae, an important component of broad‐leaved forests worldwide, with around 800 species that rely on vertebrate frugivores to disperse their seeds. A new time‐calibrated phylogeny with high support for 176 species was used to infer the biogeographic history and speciation rates based on inferences of BAMM analyses. A monophyletic Cryptocaryeae with Aspidostemon, Beilschmiedia, Cryptocarya, Dahlgrenodendron, and Eusideroxylon clades was confirmed. The five clades of Cryptocaryeae were estimated to share a common ancestor in tropical Africa or Asia in the Early Cretaceous around 123 Ma. The Beilschmiedia and Cryptocarya clades were estimated to have originated in South America around 66 Ma. Extant subclades of the Beilschmiedia clade could colonize Australia by 35 Ma and extant subclades of the Cryptocarya clade could colonize Australia by 42 Ma. Diversification rates of the Beilschmiedia clade accelerated 14 and 12 Ma after its origin and diversification rates of the Cryptocarya clade accelerated 18 Ma after its origin. Over 45% extant Cryptocaryeae species originated in the three periods of accelerated differentiation in the Miocene of Asia and Australia. Long‐distance dispersal has had a major influence on biogeography, with dispersal to Asia likely occurring seven times, Zealandia six times, America three times, Australia three times, Africa twice, and Oceania at least once. Over 70% extant Cryptocaryeae species which diverged before the Quaternary grow in the Southern Hemisphere, while 90% extant Cryptocaryeae species which diverged in the Quaternary grow in the Northern Hemisphere. The Cryptocaryeae originated in and diversified with the first angiosperm‐dominated broad‐leaved evergreen forests, from the Cretaceous to the Paleogene. Long‐distance seed dispersal, probably by birds, although possibly also by flotation, has allowed the tribe to track these forests in space and time, despite a failure to adapt to cold, dry, or highly seasonal environments.