Author's personal copy Mid-Tertiary dispersal, not Gondwanan vicariance explains distribution patterns in the wax palm subfamily (Ceroxyloideae: Arecaceae) Philipp Tre ´nel a , Mats H.G. Gustafsson a , William J. Baker b , Conny B. Asmussen-Lange c , John Dransfield b , Finn Borchsenius a, * a Department of Biological Sciences, University of Aarhus, Ny Munkegade, Building 1540, DK-8000 Aarhus C, Denmark b Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK c Department of Ecology, Royal Veterinary and Agricultural University Copenhagen, Rolighedsvej 21, DK-1958 Frederiksberg, Denmark Received 7 December 2006; revised 17 March 2007; accepted 22 March 2007 Available online 4 April 2007 Abstract The Ceroxyloideae is a small but heterogeneous subfamily of palms (Arecaceae, Palmae). It includes a Caribbean lineage (tribe Cyclo- spathae), a southern hemisphere disjunction (tribe Ceroxyleae), and an amphi-Andean element (tribe Phytelepheae), until recently con- sidered a distinct subfamily (Phytelephantoideae) due to its highly derived morphology. A variety of hypotheses have been proposed to account for the biogeography of the subfamily, involving Gondwanan vicariance, austral interplate dispersal from South America to Australia via Antarctica, Andean orogeny, and Pleistocene refuges. We assessed the systematic classification and biogeography of the group based on a densely sampled phylogeny using >5.5 kb of DNA sequences from three plastid and two nuclear genomic regions. The subfamily and each of its three tribes were resolved as monophyletic with high support. Divergence time estimates based on penal- ized likelihood and Bayesian dating methods indicate that Gondwanan vicariance is highly unlikely as an explanation for basic disjunc- tions in tribe Ceroxyleae. Alternative explanations include a mid-Tertiary trans-Atlantic/trans-African dispersal track and the ‘‘lemurian stepping stones’’ hypothesis. Austral interplate dispersal of Oraniopsis to Australia could have occurred, but apparently only in the mid- Eocene/early Oligocene interval after global cooling had begun. Our data do not support Pleistocene climatic changes as drivers for spe- ciation in the Andean-centered Phytelepheae as previously proposed. Radiation in this tribe coincides largely with the major uplift of the Andes, favoring Andean orogeny over Pleistocene climatic changes as a possible speciation-promoting factor in this tribe. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Arecaceae; Palmae; Ceroxyleae; Phytelepheae; Cyclospatheae; Molecular systematics; Molecular dating; PRK; RPB2; matK; ndhF; trnD–trnT; Dispersal; Vicariance; Gondwana; Pleistocene refuges; Andean orogeny; Austral interplate dispersal; Antarctica 1. Introduction The Ceroxyloideae is one of five subfamilies in the palm family (Arecaceae, Palmae) and comprises 8 genera and 42 species (Dranfield et al., 2005; Govaerts and Dransfield, 2005). Bringing together a small Caribbean lineage (tribe Cyclospatheae), a Gondwanan disjunction (tribe Ceroxy- leae), and a morphologically highly derived, amphi- Andean lineage (tribe Phytelepheae) previously known as subfamily Phytelephantoideae (sensu Uhl and Dransfield, 1987), the Ceroxyloideae is one of the most heterogeneous assemblages in the family, both in terms of morphology and biogeography. Furthermore, it is ecologically out- standing. In spite of its limited number of taxa, it spans a wide range of latitudes (25°N–33°S) and altitudes including the highest elevation record of any palm (Ceroxylon parvifrons, 3500 m above sea level; Borchsenius et al., 1998). It occupies a diverse array of habitats including sea- sonally dry forests (Cyclospatheae, Ceroxyleae), lowland 1055-7903/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2007.03.018 * Corresponding author. Fax: +45 89422722. E-mail address: finn.borchsenius@biology.au.dk (F. Borchsenius). www.elsevier.com/locate/ympev Molecular Phylogenetics and Evolution 45 (2007) 272–288