Bryological and Lichenological Section/ABLS
Robinson, Sean C. , Miller, Norton G. .
Experimental and Molecular Studies of Bryophyte Dispersal on Alpine Summits.
Dispersal ability is a crucial factor in determining population structure and geographic range in bryophyte species. Spores are considered to be spread in long-distance dispersal, whereas asexual propagules, such as shoot fragments, are thought to have shorter dispersal distances. However, many bryophytes rarely or never produce spores, especially in environmentally harsh habitats such as alpine summits, but very little has been done to assess fragment vs. spore dispersal in such ecosystems. Two bryophytes, Sphagnum pylaesii and S. tenellum, were compared across the Adirondack Mountains and other high elevation sites in eastern North America, using direct and indirect methods to determine the importance of vegetative fragments in dispersal. These two mosses occupy similar habitats but differ in sexual condition and amount of spore production. Samples were collected from nine alpine summits in the Adirondack High Peaks and acquired or collected from North Carolina, Tennessee, New Jersey, Maine, and boreal Canada. Population genetic analyses using 17 microsatellite loci were used to infer dispersal from gene flow estimates. To determine dispersal ability experimentally on alpine summits, shoots of different sizes were subjected to growth experiments to establish what constituted a viable reproductive propagule. From these results, branch fragments of S. pylaesii were coated with ultraviolet fluorescent dye and released from specific locations on two alpine summits. Distances traveled by fragments were measured after being located during evening surveys using ultraviolet LED light sources at 12 h, 24 h, and 1 week after initial release. Experimental and molecular results reveal that gametophytic fragments play an important role in the dispersal of this moss on and between alpine summits. In addition, genetic variation was found to be much higher than expected in both species. However, molecular data show high differentiation and low gene flow between populations of S. pylaesii throughout its North American distribution, while populations of S. tenellum were found to be less differentiated with greater levels of gene flow occurring between them.
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1 - State University of New York, University at Albany, Biology, 1400 Washington Ave., Albany, NY, 12222, USA
2 - New York State Museum, Research and Collections, 3140 Cultural Education Center, Albany, NY, 12230, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 554A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 11:45 AM