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Abstract Detail


Kao, Tzu-Tong [1], Freund, Forrest D [2], Rothfels, Carl [3], Windham, Michael D. [4], Pryer, Kathleen [5].

Low-copy nuclear data for notholaenid ferns (Pteridaceae) corroborate plastid phylogeny over traditional morphological groupings.

Notholaenids are an unusual group of ferns that have adapted to, and diversified within, the deserts of Mexico and the southwestern United States. With approximately 40 species, this group is noted for being desiccation-tolerant and consistently expressing farina across both phases of the life cycle: usually producing farina on the abaxial surface of its sporophytic leaves and along the edges of its gametophytic thallus. The farinose condition is thought to reduce water loss from transpiration and help the plants cope with excessive solar irradiation. The most recent circumscription of notholaenids is based on three plastid markers and is surprisingly incongruent with traditional groupings based on morphology. For example, two small clades, which are well-nested within notholaenids, comprise taxa never before associated with Notholaena. They differ from Notholaena by having a prominent false indusium and lacking farinose gametophytes. Furthermore, two taxa lack sporophytic farina as well, whereas the other two have chalcone-rich farinas rarely observed among notholaenids. Our aim was to assess whether the incongruities noted between the plastid phylogeny and traditional morphology-based classifications were supported by sequence data from unlinked, low-copy nuclear data. Here, we present results from four nuclear markers (~1kb each) for 65 samples (15 outgroups, and 50 notholaenids­­––including 33 out of the 38 recognized species), obtained using PacBio’s SMRT Sequencing (Sequel platform). The sequence data were sorted to different loci and alleles using the PURC Pipeline, and a species tree was inferred using ALLOPPNET implemented in BEAST. The results from our analyses are reassuringly congruent with those from the plastid data. In addition, they provide novel evidence that resolves the hybrid origin of several polyploids, and provide a solid phylogenetic basis for examining character evolution within this clade. In particular, the robust phylogenetic placement of the Notholaena standleyi species group, validates current plans to use this subclade as a model system for examining the function and evolutionary significance of farina in desert-adapted ferns.

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1 - Duke University, Biology, Box 90338, Duke University, Durham, NC, 27708, USA
2 - U.C. Berkeley, Integrative Biology, 3040 Valley Life Sciences Building #3140, Berkeley, CA, 94720-3140, USA
3 - University of California Berkeley, University Herbarium and Dept. of Integrative Biology, Berkeley, CA, 94720-2465, USA
4 - DUKE UNIVERSITY, Department Of Biology, BOX 90338, DURHAM, NC, 27708, USA
5 - Duke University, Science Drive, Durham, NC, 27708-0338, USA

low-copy nuclear genes
parallel tagged amplicon sequencing

Presentation Type: Oral Paper
Session: 6, Pteridological Section/AFS
Location: Sundance 1/Omni Hotel
Date: Monday, June 26th, 2017
Time: 9:45 AM
Number: 6002
Abstract ID:493
Candidate for Awards:Edgar T. Wherry award

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