CHANDERBALI, ANDRE*, HENK VAN DER WERFF, AND SUSANNE S. RENNER. Missouri Botanical Garden, St. Louis, MO 63166 and Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121. - Historical biogeography of neotropical Lauraceae.
Phylogenetic relationships among Lauraceae, inferred from sequence
variation in the chloroplast and nuclear genomes, suggest an early
Gondwanan and Laurasian division. Descendants of the Gondwanan lineage
form a minor element in the neotropical Lauraceae flora. Most
neotropical diversity instead is accommodated in a large terminal
clade that is nested within a paraphyletic assemblage of Laurasian
lineages. Within this terminal clade, South American lineages form
derived branches relative to clades restricted to Central America.
This supports the morphology-based hypothesis of Rohwer and Kubitzki
(1993) of a northern hemisphere origin and immigration into South
America of part of the neotropical Lauraceae stock. But when did this
immigration take place? The presence of African species of Ocotea
near the base of the neotropical clade indicates that the initial
southward movement occurred when terrestrial migration into Africa was
also possible. Molecular clock estimates of the divergence of South
American from Central American Lauraceae place the event at ~70 MYBP.
This would be consistent with a Late Cretaceous invasion of South
America —either from Central America via the Proto-Antilles arc or
from Africa— followed by extensive radiation during the isolation of
South America from the Upper Cretaceous to the Pliocene.
Key words: biogeography, Gondwana, Lauraceae, Laurasia, molecular clock, Ocotea