Ferns on Oceanic Islands - From Dispersal to Long Lasting Diversity
Geiger, Jennifer M. O. , Ranker, Tom A. .
Biogeography, diversification, and speciation of the ferns of the Hawaiian Islands.
Oceanic islands combine geographic isolation, small size and, often, geologic youth. This combination has produced biotas of low diversity and low complexity, attributes that make oceanic islands ideal locations to study the patterns and processes of speciation and diversification. The native Hawaiian fern flora is composed of approximately 140 species, classified in 67 genera. Evolutionary studies of various groups of Hawaiian ferns are allowing us to hypothesize several patterns of speciation and diversification. 1) Multiple/repeated colonizations of single, widespread species that have not undergone speciation post-colonization; e.g. Asplenium adiantum-nigrum and possibly such species as Sphenomeris chinensis, Dicranopteris linearis, and others. 2) Small radiations of species in relatively specialized habitats (e.g. epiphytes in wet forest), presumably from similar specialized species/colonizers; e.g. Grammitidaceae. 3) Small radiations of species with apparent more generalist ecological adaptation from ecologically similar, but relatively narrowly distributed non-Hawaiian colonizers; e.g. Cibotium and some of the groups of Dryopteris. 4) Single endemics diverging from widespread species but not radiating into more species rich endemic groups; e.g. Asplenium hobdyi and Dryopteris subbipinnata.
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1 - Carroll College, Department of Natural Sciences, 1601 N. Benton Ave., Helena, MT, 59625, USA
2 - University of Colorado, University Museum & Department of Ecology and Evolutionary Biology, 265 UCB, Boulder, Colorado, 80309, USA
long distance dispersal
Presentation Type: Symposium or Colloquium Presentation
Location: Lake Michigan/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:00 AM