title: Spiraling into History: A Molecular Phylogeny and Investigation of Biogeographic Origins and Floral Evolution for the GenusCostus.
abstract: Rapid radiations are notoriously difficult to resolve, yet understanding phylogenetic patterns in such lineages can be useful for investigating evolutionary processes associated with bursts of speciation and morphological diversification. Here we present an expansive molecular phylogeny ofCostusL. (Costaceae Nakai) with a focus on the Neotropical species within the clade, sampling 47 of the known 51 Neotropical species and including five molecular markers for phylogenetic analysis (ITS,ETS, rps16, trnL-F, andCaM). We use the phylogenetic results to investigate shifts in pollination syndrome, with the intention of addressing potential mechanisms leading to the rapid radiation documented for this clade. Our ancestral reconstruction of pollination syndrome presents the first evidence in this genus of an evolutionary toggle in pollination morphologies, demonstrating both the multiple independent evolutions of ornithophily (bird pollination) as well as reversals to melittophily (bee pollination). We show that the ornithophilous morphology has evolved at least eight times independently with four potential reversals to melittophilous morphology, and confirm prior work showing that neither pollination syndrome defines a monophyletic lineage. Based on the current distribution for the Neotropical and African species, we reconstruct the ancestral distribution of the Neotropical clade as the Pacific Coast of Mexico and Central America. Our results indicate an historic dispersal of a bee-pollinated taxon from Africa to the Pacific Coast of Mexico/Central America, with subsequent diversification leading to the evolution of a bird-pollinated floral morphology in multiple derived lineages.
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Shayla
authors.initials: S
authors.lastname: Salzman
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Driscoll
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Tanya
authors.initials: T
authors.lastname: Renner
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Thiago
authors.initials: T
authors.lastname: André
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Stacy
authors.initials: S
authors.lastname: Shen
authors.affiliation: Departments of Plant and Microbial Biology and Integrative Biology and The University and Jepson Herbaria, 431 Koshland Hall, University of California, Berkeley, California 94720 U. S. A.
authors.forename: Chelsea D
authors.initials: CD
authors.lastname: Specht
keywords: Ancestral state reconstruction; Costaceae; Zingiberales; rapid radiation