Biogeography of Lauraceae: Evidence from the Chloroplast and Nuclear Genomes1

Phylogenetic relationships among 122 species of Lauraceae representing 44 of the 55 currently recognized genera are inferred from sequence variation in the chloroplast and nuclear genomes. The trnL-trnF, trnT-trnL, psbA-trnH, and rpll6 regions of cpDNA, and the 5' end of 26S rDNA resolved major lineages, while the ITS/5.8S region of rDNA resolved a large terminal lade. The phylogenetic estimate is used to assess morphology-based views of relationships and, with a temporal dimension added, to reconstruct the biogeographic history of the family. Results suggest Lauraceae radiated when trans-Tethyean migration was relatively easy, and basal lineages are established on either Gondwanan or Laurasian terrains by the Late Cretaceous. Most genera with Gondwanan histories place in Cryptocaryeae, but a small group of South American genera, the Chlorocardium-Mezilauruls lade, represent a separate Gondwanan lineage. Caryodaphnopsis and Neocinnamomum may be the only extant representatives of the ancient Lauraceae flora documented in Midto Late Cretaceous Laurasian strata. Remaining genera place in a terminal Perseeae-Laureae lade that radiated in Early Eocene Laurasia. Therein, non-cupulate genera associate as the Persea group, and cupuliferous genera sort to Laureae of most classifications or Cinnamomeae sensu Kostermans. Laureae are Laurasian relicts in Asia. The Persea group and Cinnamomum group (of Cinnamomeae) show tropical amphi-Pacific disjunctions here credited to disruption of boreotropical ranges by Eocene-Oligocene climatic cooling. The Ocotea complex accommodates remaining Cinnamomeae and shows a trans-Atlantic disjunction possibly derived from a Madrean-Tethyan ancestral distribution. These findings support Laurasian ancestry for most extant Lauraceae, with their considerable neotropical representation primarily derived from Early Miocene radiation of the Ocotea complex upon reaching South America.