The biogeographical history of the mulberry family (Moraceae) was investigated using phylogenetic inferences from nuclear and chloroplast DNA, molecular dating with multiple fossil calibrations, and independent geological evidence. The Moraceae are centered in the tropics which has invited the hypothesis that the family has Gondwanan origins and extant distribution is the result of vicariance due to the break-up of Gondwana. However, the cosmopolitan distribution of Moraceae suggests a more complicated biogeographical history. The timing and location of Moraceae diversification also bears on the origin of the fig pollination mutualism, a model for the study of coevolution and specialization. Recent molecular dating of pollinating fig wasps suggested that an ancient Gondwanan origin coupled with vicariance and dispersal could account for the present day distribution of the mutualism. Here, we provide the first assessment of this hypothesis based on dating of figs and their relatives. Minimum age estimates suggest that the Moraceae had diversified by at least the mid-Cretaceous and major clades including the figs may have radiated during the Tertiary after the break-up of Gondwanaland. Molecular evidence together with Eurasian fossils suggest that the early diversification of Moraceae in Eurasia and subsequent migration into the southern hemisphere is at least as plausible as the Gondwanan hypothesis. These findings invite a reevaluation of the biogeography of fig pollination and highlight the need for incorporating multiple sources of evidence in biogeographical reconstructions.
Bibliographical noteFunding Information:
We thank C.C. Berg, N. Rønsted, and F.K. Barker for helpful discussion, two anonymous reviewers for comments, and S.J. Swenson for laboratory assistance. We also acknowledge the US National Science Foundation, National Research Institute of Papua New Guinea, Forest Research Institute of Papua New Guinea, New Guinea Binatang Research Center, Organization for Tropical Studies, Centre National de la Recherche Scientifique, National Museum of Natural History, Smithsonian Tropical Research Institute, Field Museum of Natural History, Harvard University Herbaria, Nationaal Herbarium Nederland (Leiden), Bell Museum of Natural History, and the Supercomputing Institute at the University of Minnesota. This material is based upon work supported by the National Science Foundation under Grant No. DEB 0128833.
Copyright 2008 Elsevier B.V., All rights reserved.
- Bayesian analysis
- Fig pollination
- Molecular dating