Phylogenetics and Biogeography of Santalales

The order Santalales comprises a diverse assemblage of hemiparasitic and holoparasitic angiosperms, including mistletoes, sandalwoods and root parasites, with c. 18 families and over 2,200 species. Modern molecular phylogenetic studies have resolved major clades within the order, demonstrating that parasitism evolved multiple times and that traditional family circumscriptions often masked deeper relationships. Plastid and nuclear DNA sequences have clarified the monophyly of core lineages such as Loranthaceae and Santalaceae, while revealing unexpected sister-group links between Balanophoraceae and other root-parasite clades. Time-calibrated trees indicate that the crown group of Santalales originated in the Late Cretaceous, with key radiations in the early Cenozoic coinciding with the emergence of avian frugivores and shifts in global climate. Geographical reconstructions suggest an early diversification in Gondwanan regions, followed by dispersal into Laurasian continents. Clade-specific biogeographic histories show distinct trajectories: mistletoes of the Loranthaceae diversified across Australasia and the Neotropics via bird-mediated seed dispersal, whereas sandalwoods and Osyrideae underwent repeated colonisations of Africa, Asia and Europe. Adaptive traits such as specialised haustorial structures and reductions in vegetative organs have accompanied host shifts, enabling Santalales to exploit a wide range of woody and herbaceous hosts. These evolutionary innovations underpin the ecological significance of the order, from keystone interactions in tropical forests to the cultural importance of sandalwood production and mistletoe symbolism.

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Phylogenetics and Biogeography of Santalales publication trend

The graph below shows the total number of articles in phylogenetics and biogeography of santalales across all publications each year (not limited to Nature Index journals).

Technical terms

Phylogenetics: The study of evolutionary relationships among species or groups, typically inferred from molecular or morphological data to construct branching diagrams (phylogenetic trees).

Biogeography: The discipline concerned with the geographic distribution of organisms through time, incorporating processes such as dispersal, vicariance and extinction.

Monophyly: A property of a group (clade) whereby all members share a common ancestor and include all descendants of that ancestor.

Molecular clock: A method for estimating divergence times by assuming a relatively constant rate of molecular change over evolutionary history, calibrated using fossil or geological data.

Ancestral character reconstruction: Analytical techniques used to infer the traits of common ancestors based on observed states in living species and a phylogenetic tree.

References

1. Phylogeny, character evolution and historical biogeography of Scurrulinae (Loranthaceae): new insights into the circumscription of the genus Taxillus. BMC Plant Biology (2024).
2. Evolution of pollen morphology in Loranthaceae. Grana (2017).
3. Eocene Loranthaceae pollen pushes back divergence ages for major splits in the family. PeerJ (2017).