Abstract Detail



Paleobotany

Atkinson, Brian [1].

Fossils, form, and genes: Exploring the overall pylogenetic pattern of Cornales.

Recent paleobotanical and molecular phylogenetic studies have revealed that the early diverging asterid order, Cornales underwent an extensive diversification prior to 90 Ma in the Late Cretaceous. This phylogenetic radiation was rapid and resulted in 10 families within five major clades: 1) Cornaceae-Alangiaceae; 2) Nyssaceae-Mastixiaceae-Davidiaceae [NMD clade]; 3) Curtisiaceae-Grubbiaceae; 4) Hydrangeaceae-Loasaceae; and 5) Hydrostachyaceae. However, due to the rapid nature of the initial cornalean radiation, relationships among major clades are not well understood. In order to more fully elucidate the overall pattern of cornalean phylogeny, fossil, morphological, and molecular data were combined and analysed within Bayesian inference (BI) and maximum-likelihood (ML) frameworks. The concatenated matrix consists of six chloroplast genes, 26s nuclear DNA data, and a fruit morphological matrix of 71 characters. A total of 88 taxa (including 26 extinct species) were scored for morphology. Various iterations of the matrix were performed (molecular only; combined analysis of extant species only; and combined analyses with varying inclusions of fossils). Preliminary BI and ML analyses recovered similar topologies with relationships of major clades consistent with those recovered in recent molecular-based studies. Total-evidence analyses reveal that all cornalean fossils are nested within the crown-group of the order and those that have been assigned to extant genera and families are recovered according to their respective taxonomic assignments. Several Cretaceous species (that are not assignable to extant families) formed a monophyletic group nested within a Cornaceae-Alangiaceae+Curtisiaceae-Grubbiaceae clade. However, this “Cretaceous” clade has low support and when its constituent species are individually included in separate analyses, they are found in different positions within the tree. The phylogenetic placement of these fossils help set a foundation for future comparative analyses and will be used to infer the temporal and morphological evolution of Cornales.


1 - University Of Kansas, Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, 2041 Haworth Hall, Lawrence, KS, 66045, United States

Keywords:
fruits
fossils
Cretaceous
total evidence phylogeny.

Presentation Type: Oral Paper
Number: 0006
Abstract ID:627
Candidate for Awards:None


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