McCarthy, Mirabai , Hickey, R. James .
Bryophyte Influence on Terrestrial and Epiphytic Fern Gametophytes.
The unique climate and structural complexity of tropical forests enable vertical habitat differentiation between terrestrial and epiphytic zones. These habitats are spatially overlapping in nature and there are no known barriers to dispersal of fern spores between them. Because spores are copiously released, one might expect to find species growing in both places, yet taxa are typically confined to one particular habitat type. The goal of this study was to better understand how epiphytic and terrestrial species are restricted by habitat. Epiphytic, Phlebodium aureum, Neurodium lanceolatum, Campyloneuron phyllitidis, and terrestrial Adiantum tenerum, Thelypteris augescens, and Pteris bahamensis were collected in the tropics as spore sources. Three epiphytic substrates (moss, leafy liverwort, and lichen) and one terrestrial substrate (soil) were also collected. Spores of each species were discretely sown directly onto these substrates and onto agar-substrate combinations, then placed in a growth chamber under uniform conditions where development was monitored. Gametophytes of all terrestrial species sown directly on leafy liverwort were significantly reduced in size and throughout the duration of this study never reached sexual maturity. On agar-bryophyte combinations we identified a positive correlation between distance from the epiphytic substrates and the size of terrestrial gametophytes. In contrast, gametophytes of epiphytic species developed normally regardless of media and substrate. These observations suggest the possibility that epiphytic bryophytes have a negative impact on terrestrial gametophyte development, perhaps through allelopathy. Such interactions between substrate and terrestrial gametophytes might represent a limiting factor for the establishment of terrestrial species in epiphytic habitats.
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1 - Department of Botany, 316 Pearson Hall, Oxford, Ohio, 45056, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM