Inter-island but not intra-island divergence among populations of sea oats, Uniola paniculata L. (Poaceae)
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RESEARCH ARTICLE
Inter-island but not intra-island divergence among populations of sea oats, Uniola paniculata L. (Poaceae) Cara L. Gormally • J. L. Hamrick Lisa A. Donovan
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Received: 29 May 2012 / Accepted: 18 December 2012 / Published online: 28 December 2012 Ó Springer Science+Business Media Dordrecht 2012
Abstract Understanding the underlying causes of phenotypic trait variation among populations is important for informing conservation decisions. This knowledge can be used to determine whether locality matters when sourcing populations for habitat restoration. Uniola paniculata is a federally protected coastal dune grass native to the southeastern Atlantic and the Gulf coasts of the USA that is often used to stabilize restored dune habitats. This study uses neutral genetic markers (allozymes) and a greenhouse common garden study to determine the relative contributions of neutral evolutionary processes and natural selection to patterns of phenotypic variation among natural populations of U. paniculata. Seeds were sourced from foredune and backdune populations spanning shoreline-tolandward environmental gradients on each of four Georgia barrier islands. Based on previous work, we expected to find evidence of divergent selection among populations located on the shoreline-to-landward environmental gradient. However, differences among islands, rather than intraisland habitat differences, drive divergent selection on aboveground and total biomass. The lack of evidence for divergent selection across the shoreline-to-landward gradient suggests that previously documented intra-island trait variation is likely due to phenotypic plasticity. Our findings have implications for conservation and restoration efforts involving U. paniculata, as there is evidence for divergent
C. L. Gormally J. L. Hamrick L. A. Donovan Department of Plant Biology, University of Georgia, 2502 Miller Plant Sciences, 30602 Athens, Georgia C. L. Gormally (&) School of Biology, Georgia Institute of Technology, 310 Ferst Drive, 30332 Atlanta, Georgia e-mail: [email protected]
selection among populations located on neighboring islands. Keywords FST Allozymes QST Population differentiation Uniola paniculata Coastal dunes
Introduction Determining mechanisms that underlie trait variation among populations is particularly critical for informing restoration and conservation decisions, e.g., choosing plant material for transplanting, and maintaining genetic diversity and adaptive potential (Lynch 1996; Sgro et al. 2011). The source of transplanted plant material may have a profound effect on the success of transplant establishment, due to the adaptation of populations to local environmental conditions (Rice et al. 1997; McKay et al. 2005 and see a meta-analysis by Hereford (2009) for an in-depth discussion of local adaptation and fitness). However, multiple evolutionary and ecological processes may produce trait variation, including local adaption due to divergent selection among heterogeneous environmental conditions (Ture
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