Experimental and Molecular Studies of Bryophyte Dispersal on Alpine Summits
|Date(s)|| 02/04/2013 - 4:00 p.m.
|Location||Donahue Auditorium, Gordon Science Center|
|Presenter||Sean Robinson, Ph.D., Lecturer, Department of Biology, SUNY Oneonta|
|Description|| Abstract: In bryophytes, spores are considered to be the primary agents of long-distance dispersal, whereas asexual propagules, such as shoot fragments, are thought to have shorter dispersal distances. Many bryophytes, however, rarely or never produce spores, especially in environmentally harsh habitats such as alpine summits. A review of bryophyte dispersal studies over the last sixty years revealed that the role of gametophytic fragments in bryophyte population dynamics has not been adequately addressed. Sphagnum pylaesii reproduces primarily by fragmentation, yet it maintains large populations on several of the Adirondack alpine summits. The importance of vegetative fragments in the dispersal of this species was evaluated in parallel comparative studies of Sphagnum tenellum using direct and indirect methods. S. tenellum occupies similar habitats but differs in sexual condition and amount of spore production. To determine dispersal ability experimentally on alpine summits, branch fragments 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 24 h after initial release. These data fit a leptokurtic distribution, with a maximum dispersal distance of 54 m, the longest distance measured for wind dispersed bryophyte fragments. Dispersal ability of S. pylaesii fragments was assessed further by releasing fragments in a wind tunnel at varying wind speeds. These experiments support the field experiments, showing maximum fragment dispersal at wind speeds below mean wind speeds measured on the summit of Mt. Marcy. As an indirect measure of dispersal between the Adirondack summits, population differentiation (FST), and estimated gene flow (Nm) were calculated from genetic variation at fifteen microsatellite loci. Molecular data support the hypothesis that Sphagnum pylaesii has dispersed successfully among summits through fragmentation, given a lack of genetic variability (P = 0, A = 0), and consequently no differentiation (FST = 0) and high gene flow (Nm = ?) between the summits.
The Asa Gray Seminar Series is sponsored by the Asa Gray Biological Society, and is the longest running seminar series at Utica College. Scientists are invited from throughout the region to present seminars on their ongoing research.
All lectures are held in Donahue Auditorium, Gordon Science Center, at 4:00 p.m. An informal reception immediately follows. Call (315) 792-3028 for more information.
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