Inferring geographic range evolution of a pantropical tribe in the coffee family (Lasiantheae, Rubiaceae) in the face of topological uncertainty Jenny E.E. Smedmark a,b,⇑ , Sylvain G. Razafimandimbison a , Niklas Wikström a , Birgitta Bremer a a Bergius Foundation, Royal Swedish Academy of Sciences, and Department of Ecology, Environment, and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden b University of Bergen, University Museum of Bergen, The Natural History Collections, Post Box 7800, NO-5020 Bergen, Norway article info Article history: Received 4 April 2013 Revised 6 September 2013 Accepted 9 September 2013 Available online 19 September 2013 Keywords: Dispersal–extinction–cladogenesis Divergence time estimation Historical biogeography Lasiantheae Phylogeny Rubiaceae abstract In this study we explore what historical biogeographic events are responsible for the wide and disjunct distribution of extant species in Lasiantheae, a pantropical group of trees and shrubs in the coffee family. Three of the genera in the group, Lasianthus, Saldinia, and Trichostachys, are found to be monophyletic, while there are indications that the fourth, Ronabea, is paraphyletic. We also address how the uncertainty in topology and divergence times affects the level of confidence in the biogeographic reconstruction. A data set consisting of chloroplast and nuclear ribosomal DNA data was analyzed using a Bayesian relaxed molecular clock approach to estimate phylogenetic relationships and divergence times, and the dis- persal–extinction–cladogenesis (DEC) method to reconstruct geographic range evolution. Our results show that the Lasiantheae stem lineage originated in the neotropics, and the group expanded its range to the palaeotropics during the Eocene, either by continental migration through the boreotropics or by transatlantic long-distance dispersal. Two cases of Oligocene/Miocene over water-dispersal were also inferred, once from the paleotropics to the neotropics within Lasianthus, and once to Madagascar, concur- rent with the origin of Saldinia. A lot of the diversification within Lasianthus took place during the Mio- cene and may have been influenced by climatic factors such as a period of markedly warm and moist climate in Asia and the aridification of the interior of the African continent. When biogeographic recon- structions were averaged over a random sample of 1000 dated phylogenies, the confidence in the biogeo- graphic reconstruction decreased for most nodes, compared to when a single topology was used. A good understanding of phylogenetic relationships is necessary to understand the biogeographic history of a group, bit since the phylogeny is rarely completely known it is important to include phylogenetic uncer- tainty in biogeographic analysis. For nodes where the resolution is uncertain, the use of a single ‘‘best’’ topology as a basis for biogeographic analysis will result in inflated confidence in a biogeographic recon- struction which may be just one of several possible reconstructions. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction Lasiantheae is a group in the coffee family comprising more than 260 species of mainly shrubs and small trees. It consists of four genera, three of which have restricted but widely separated geographic ranges; Ronabea in tropical America, Trichostachys in West Africa, and Saldinia in Madagascar; and one which is pantrop- ical, Lasianthus. Species in Lasiantheae occur nearly exclusively in the understory of tropical rainforests. Understanding the biogeo- graphic history of this group may therefore aid in the search for shared patterns among different organismal groups that can explain how the world’s most species-rich ecosystems, the tropical rainforests (Morley, 2000), have been assembled. Based on available evidence, it seems unlikely that Lasiantheae should be old enough for the pantropical distribution pattern of ex- tant members of the group (Fig. 1) to be a remnant of a Gondwanan distribution. Had this been the case, we might have expected Lasiantheae to have been represented in the fossil record from the Cretaceous of the former Gondwanan continents. On the con- trary, the oldest fossil that can be assigned to Rubiaceae, Paleorubi- aceophyllum eocenicum, was found in North America and appears in strata from the Eocene (Roth and Dilcher, 1979). A previous molec- ular dating analysis indicated that the Rubiaceae crown group is 86.6 Myr (95% HPD 73–101 Myr, Bremer and Eriksson, 2009), which is too young for any splits between sister groups occurring in the old and new worlds to be explained by Gondwanan vicari- ance, as the connection between the African and South American plates was broken 96 Ma (Morley, 2003). Studies of the 1055-7903/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ympev.2013.09.007 ⇑ Corresponding author at: University of Bergen, University Museum of Bergen, The Natural History Collections, Post Box 7800, NO-5020 Bergen, Norway. E-mail addresses: jenny.smedmark@um.uib.no (J.E.E. Smedmark), sylvain@ bergianska.se (S.G. Razafimandimbison), niklas@bergianska.se (N. Wikström), birgitta.bremer@bergianska.se (B. Bremer). Molecular Phylogenetics and Evolution 70 (2014) 182–194 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev