Culley, Theresa M. , Weller, Stephen G. , Sakai, Ann K. .
Genetic variation in the Hawaiian endemic subshrub Schiedea globosa (Caryophyllaceae) and implications for inter-island dispersal.
The genetic structure of populations of insular taxa can be impacted by various ecological factors, such as founder effects, increased extinction, and dispersal patterns within and among islands. This is especially true in the Hawaiian Islands where small populations of native plant species often are endangered by introduced herbivores and loss of habitat. Our objective was to test the hypothesis that genetic variation in populations of the subshrub Schiedea globosa is shaped by these ecological factors and especially by its past colonization and dispersal history. Using nine allozyme loci and 12 microsatellite loci, we quantified genetic variation in 11 populations of S. globosa located on the islands of Hawaii, Maui, Molokai, and Oahu. Both allozyme and microsatellite markers revealed significant genetic differentiation among populations (θallozyme = 0.30; θmicrosat = 0.25), with moderate genetic variation detected within each population, regardless of molecular marker used. Populations from the same island were genetically most similar to one another, with a significant association between genetic and geographic distances (r = 0.97; P = 0.009). Overall, allozyme and microsatellite markers gave similar results, indicating limited gene flow among populations on different islands, consistent with infrequent dispersal occurring in a step-wise fashion from the oldest to the newest islands (Oahu > Molokai > Maui > Hawaii). Thus, the genetic structure of S. globosa appears to reflect a combination of factors, including limited inter-island dispersal and colonization events, which ultimately may affect the ability of the species to adapt to a changing environment.
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1 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, Ohio, 45221, USA
2 - University of California Irvine, Department of Ecology & Evolutionary Biology, 321 Steinhaus Hall, Irvine, California, 92697-2525, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, July 29th, 2008
Time: 10:45 AM