Mchenry, Monique , Barrington, David .
Investigating morphological diversity of Andean Polystichum (Dryopteridaceae): seeking explanations for incongruence between sequence variation and morphological variation.
The northern and central Andes represent the third highest center of endemism in the fern genus Polystichum (Dryopteridaceae). Previous work on Polystichum in South America has circumscribed taxa based on morphological characters alone. We explored patterns of both sequence and morphological variation in two sister subclades of monophyletic Andean Polystichum, the orbiculatum subclade and the montevidense subclade. Our results from phylogenetic analyses based on plastid and nuclear markers suggest an interesting paradox: one subclade exemplifies cryptic speciation with morphologically similar taxa that exhibit high sequence variation, whereas the other subclade exhibits the inverse - low sequence variation with high morphological variation. From these results we conclude that geographically disjunct entities in the montvidense subclade exhibit identical morphologies despite significant sequence divergence due to convergent evolution of morphological characters, leading to underdescription of species. In the orbiculatum subclade, by contrast, high morphological variation correlates to different ecological and developmental factors, leading to an abundance of names pertaining to a single widespread taxon. With our improved understanding of morphological variation in Andean Polystichum we will move on to exploring the patterns of speciation in the northern and central Andes.
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1 - University of Vermont, Plant Biology, Jeffords Hall, Burlington, VT, 05405, United States
2 - University Of Vermont, DEPT OF PLANT BIOLOGY, Burlington, VT, 05405-0086, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Waterman Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 11:15 AM