title: Temperate radiations and dying embers of a tropical past: the diversification of Viburnum.
abstract: We used a near-complete phylogeny for the angiosperm clade Viburnum to assess lineage diversification rates, and to examine possible morphological and ecological factors driving radiations. Maximum-likelihood and Bayesian approaches identified shifts in diversification rate and possible links to character evolution. We inferred the ancestral environment for Viburnum and changes in diversification dynamics associated with subsequent biome shifts. Viburnum probably diversified in tropical forests of Southeast Asia in the Eocene, with three subsequent radiations in temperate clades during the Miocene. Four traits (purple fruits, extrafloral nectaries, bud scales and toothed leaves) were statistically associated with higher rates of diversification. However, we argue that these traits are unlikely to be driving diversification directly. Instead, two radiations were associated with the occupation of mountainous regions and a third with repeated shifts between colder and warmer temperate forests. Early-branching depauperate lineages imply that the rare lowland tropical species are 'dying embers' of once more diverse lineages; net diversification rates in Viburnum likely decreased in these tropical environments after the Oligocene. We suggest that 'taxon pulse' dynamics might characterize other temperate plant lineages.
authors: Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA.
authors: Elizabeth L
authors: http://orcid.org/0000-0002-2746-4863
authors: EL
authors: Spriggs
authors: Department of Biology, The College of New Jersey, 2000 Pennington Rd, Ewing, NJ, 08628, USA.
authors: Wendy L
authors: WL
authors: Clement
authors: Division of Botany, Peabody Museum of Natural History, Yale University, PO Box 208118, New Haven, CT, 06520, USA.
authors: Patrick W
authors: PW
authors: Sweeney
authors: Laboratorio de Botánica y Sistemática, Departamento de Ciencias Biológicas, Universidad de los Andes, Apartado Aéreo 4976, Bogotá, Colombia.
authors: Santiago
authors: S
authors: Madriñán
authors: Department of Ecology and Evolutionary Biology, Brown University, Box G-W, 80 Waterman Street, Providence, RI, 02912, USA.
authors: Erika J
authors: EJ
authors: Edwards
authors: Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA.
authors: Michael J
authors: MJ
authors: Donoghue
mesh_terms: D001499:Bayes Theorem; D044822:Biodiversity; D005075:Biological Evolution; D002980:Climate; D004463:Ecology; D017753:Ecosystem; D010641:Phenotype; D010802:Phylogeny; D065947:Rainforest; D013696:Temperature; D027925:Viburnum / Q000235:genetics*
keywords: Viburnum; biome shift; diversification; extinction rate; speciation rate; taxon pulse; temperate forests; tropical forests