Abstract Detail


Steven, Janet [1], Decatur, George [2], Quick-Cole, Emily [3].

Evidence for mechanisms that promote outcrossing in the homosporous fern Osmunda claytoniana .

Homosporous ferns are potentially capable of both gametophytic and sporophytic selfing, but many fern species show evidence for a predominately outcrossing breeding system.  To investigate the possible presence of mechanisms promoting outcrossing in in Osmunda claytoniana, we observed gamtetophyte development at varying densities and estimated the frequency of sporophytic outcrossing. In groups of gametophytes grown on agar, gametophytes producing only one kind of gametangia were more common than hermaphroditic gametophytes.  After twelve weeks, 73% of the gametophytes had developed antheridia while only 45% possessed archegonia. Plates with higher densities of gametophytes were more likely to have gametophytes with only antheridia. These findings are consistent with the presence of an antheridiogen system, in which expression of antheridiogens by gametophytes with early-developing archegonia promote the development of antheridia on nearby gametophytes. We also sowed spores from two sporophytes homozygous for different alleles at a microsatellite locus in pots and genotyped the sporophyte offspring. Sixty-nine percent of the offspring were the product of sporophytic outcrossing, and the frequency of heterozygous offspring was consistent with random mating among gametophytes.  Osmunda claytoniana appears to possess a mating system that suppresses gametophytic selfing.

1 - Christopher Newport University, Department Of Organismal And Environmental Biology, 1 Avenue Of The Arts, Newport News, VA, 23606, United States
2 - Christopher Newport University, Organismal and Environmental Biology, 1 Avenue of the Arts, Newport News, VA, 23606, USA
3 - New Horizons Governor's School for Science and Technology, 520 Butler Farm Road, Hampton, VA, 23666, USA


Presentation Type: Poster
Number: PPT003
Abstract ID:272
Candidate for Awards:None

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