Bryological and Lichenological Section/ABLS
Wickett, Norman , Goffinet, Bernard .
Relationships of the non-photosynthetic liverwort Cryptothallus mirabilis (Metzgeriales, Aneuraceae) based on four loci.
Cryptothallus mirabilis is distinguished from other liverworts in the Aneuraceae by its unusual life history: it is subterranean, non-photosynthetic, and relies on a fungal endophyte to deliver carbon from a host tree. However, very few characters unrelated to its life history clearly separate the genus from Aneura, suggesting that Cryptothallus may simply be an albino Aneura. Apart from its unique mode of nutrition and lack of chlorophyll, only sporophyte and, particularly, spore characteristics separate the two genera. The spores of Cryptothallus are retained in tetrads and have reticulate thickenings, both of which are unique for the family. Understanding the relationships of C. mirabilis is crucial for testing hypotheses of genomic evolution. Vascular plants with similar life histories (non-photosynthetic) exhibit, to varying degrees, reduction in the structure and function of the chloroplast genome. If such patterns are to be tested in liverworts, the most suitable exemplar for genomic comparisons must be identified in order to determine features of the chloroplast genome resulting from the loss of photosynthesis rather that due to common ancestry. Four loci were sequenced to address this question: rps4, the trnL - trnF region, the atpB - rbcL spacer, and the nuclear internal transcribed spacer (ITS) region. Taxa were sampled from the Aneuraceae sensu Crandall-Stotler and Stotler (2000) which includes Aneura, Cryptothallus, Lobatiriccardia, and Riccardia. Results of phylogenetic analyses support the close relationship between Aneura and Cryptothallus, and confirm the suitability of Aneura for use in testing hypotheses of chloroplast genome evolution.
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1 - University of Connecticut, Department of Ecology & Evolutionary Biology, 75 North Eagleville Rd. U-3043, Storrs, Connecticut, 06269-3043, USA
Presentation Type: Oral Paper
Location: Salon A - Gov Ballroom/Hilton
Date: Monday, August 15th, 2005
Time: 2:15 PM