Abstract Detail



PhyloCode 2020: Naming the Tree of Life

Mathews, Sarah [1], Stevenson, Dennis W. [2].

Advances in the phylogenetics of cycads and phylogenetic definitions for cycad clades.

Relationships among clades of living cycads have been greatly clarified in molecular systematic studies, but the positions of Bowenia and Stangeria have remained uncertain, making it difficult to propose formal phylogenetic definitions for several clades in the cycad tree. The taxonomic classification of Stevenson (1992) defined the family Stangeriaceae to comprise these two genera, based on cladistic analyses of morphological data. More recent phylogenetic analyses of morphological data have supported their sister group relationship, but analyses of combined molecular and morphological data or just molecular data have not. Instead, molecular trees resolve the position of Stangeria as sister to Ceratozamia with strong support, and this is consistent with trees from molecular and morphological data combined. Bowenia, on the other hand, is resolved with strong support as sister to a clade of MacrozamiaLepidozamia, and Encephalartos in molecular trees, which not consistent with its position in trees from molecular and morphological data combined. Results from our exploration of these conflicts with a new morphological data set that has been expanded to include recently characterized fossils and additional living species are providing a basis on which to propose formal phylogenetic definitions for clades in the tree of extant cycads, and to provide a stable nomenclature that encompasses insights from both extensive molecular sampling and the rich fossil history of cycads.


1 - Louisiana State University, Biological Sciences, 202 Life Sciences Building, Baton Rouge, LA, 70803, United States
2 - New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458, USA

Keywords:
Cycads
PhyloCode
phylogeny
fossils
Molecular 
Morphological.

Presentation Type: Colloquium Presentations
Number:
Abstract ID:1013
Candidate for Awards:None


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