Ferns on Oceanic Islands - From Dispersal to Long Lasting Diversity
Ranker, Tom A. , Schneider, Harald .
Overview of fern floras on Oceanic Islands.
The stage was set for the present symposium by two pivotal papers published in the early 1970s by Rolla M. Tryon (Development and evolution of fern floras of oceanic islands; Biotropica 2: 76-84, 1970) and Alan R. Smith (Comparison of fern and flowering plant distributions with some evolutionary interpretations for ferns; Biotropica 4: 4-9, 1972). A common theme of these and other works has been the importance of the higher dispersability of homosporous ferns and homosporous lycophytes compared to seed plants and other heterosporous land plants and the impact this feature has on community assembly, diversification, and speciation on oceanic islands. High dispersability via wind-blown spores has generally led to greater similarity in floristic composition on islands compared to source areas and lower levels of endemism. High dispersability also accounts for the rapidity of colonization of new islands and new lava flows on volcanic islands and, thus, the important role of ferns in the early stages of community assembly, floristic composition, and ecological succession. Effective migration and establishment do not necessarily follow from dispersal and depend on other critical life-history attributes of species, such as: the ability of spores to withstand extreme temperatures and high levels of UV radiation during dispersal and different aspects of gametophyte biology, e.g., ontogeny, sexuality, clonality, and ecology, and their interplay with genetic diversity and competitive ability of fern species. In conclusion, various aspects of fern dispersal biology can be explored using oceanic islands as natural laboratories. Since the landmark papers of the 1970s, the application of DNA-based approaches has revolutionized our knowledge of fern evolution and it is timely to approach these laboratories with the tools of the 21st century.
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1 - University of Colorado, University Museum & Department of Ecology and Evolutionary Biology, 265 UCB, Boulder, Colorado, 80309, USA
2 - Natural History Museum, Cromwell Road, London, SW7 5BD, UK
Presentation Type: Symposium or Colloquium Presentation
Location: Lake Michigan/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:00 AM