title: Hybridization among distantly related species: Examples from the polyploid genus Curcuma (Zingiberaceae).
abstract: Discerning relationships among species evolved by reticulate and/or polyploid evolution is not an easy task, although it is widely discussed. The economically important genus Curcuma (ca. 120 spp.; Zingiberaceae), broadly distributed in tropical SE Asia, is a particularly interesting example of a group of palaeopolyploid origin whose evolution is driven mainly by hybridization and polyploidization. Although a phylogeny and a new infrageneric classification of Curcuma, based on commonly used molecular markers (ITS and cpDNA), have recently been proposed, significant evolutionary questions remain unresolved. We applied a multilocus approach and a combination of modern analytical methods to this genus to distinguish causes of gene tree incongruence and to identify hybrids and their parental species. Five independent regions of nuclear DNA (DCS, GAPDH, GLOBOSA3, LEAFY, ITS) and four non-coding cpDNA regions (trnL-trnF, trnT-trnL, psbA-trnH and matK), analysed as a single locus, were employed to construct a species tree and hybrid species trees using (*)BEAST and STEM-hy. Detection of hybridogenous species in the dataset was also conducted using the posterior predictive checking approach as implemented in JML. The resulting species tree outlines the relationships among major evolutionary lineages within Curcuma, which were previously unresolved or which conflicted depending upon whether they were based on ITS or cpDNA markers. Moreover, by using the additional markers in tests of plausible topologies of hybrid species trees for C. vamana, C. candida, C. roscoeana and C. myanmarensis suggested by previous molecular and morphological evidence, we found strong evidence that all the species except C. candida are of subgeneric hybrid origin.
authors.affiliation: Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic. Electronic address: zaveskae@email.cz.
authors.forename: Eliška
authors.initials: E
authors.lastname: Záveská
authors.affiliation: Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Fér
authors.affiliation: Department of Botany, National Museum in Prague, Prague, Czech Republic.
authors.forename: Otakar
authors.initials: O
authors.lastname: Šída
authors.affiliation: Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic; Institute of Botany, Slovak Academy of Sciences, Bratislava, Slovak Republic.
authors.forename: Karol
authors.initials: K
authors.lastname: Marhold
authors.affiliation: The Herbarium, Singapore Botanic Gardens, Singapore.
authors.forename: Jana
authors.initials: J
authors.lastname: Leong-Škorničková
mesh_terms: D001208:Asia; D030024:Curcuma / Q000235:genetics*; D018742:DNA, Chloroplast / Q000235:genetics; D019143:Evolution, Molecular; D017343:Genes, Plant; D006824:Hybridization, Genetic; D010802:Phylogeny; D011123:Polyploidy; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast
keywords: Curcuma myanmarensis; Curcuma roscoeana; Curcuma vamana; Hybrid species tree; Multilocus species tree; Nuclear low-copy genes