POLLINATOR SPECIALIZATION AND THE EVOLUTION OF POLLINATION SYNDROMES IN THE RELATED SILENE, S. CAROLINIANA, S. VIRGINICA, AND S. STELLATA

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dc.contributor.advisorFenster, Charles B.en_US
dc.contributor.advisorDudash, Michele R.en_US
dc.contributor.authorReynolds, Richard Jamesen_US
dc.contributor.departmentBiologyen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2008-10-11T05:34:44Z
dc.date.available2008-10-11T05:34:44Z
dc.date.issued2008-05-23en_US
dc.description.abstractPollination syndromes are the convergent expression of floral traits in unrelated species reflecting specialized interactions between plants and pollinators exerting similar selection pressures. I addressed the controversial claim that pollinator-mediated selection is unlikely to be a major factor underlying floral evolution because plants often have many functionally different floral visitors. Detailed pollination data and pollinator-mediated selection studies are needed to address the notion that specialized plant-pollinator interactions are a major mechanism of floral evolution. I developed statistical methods to measure the importance of pollinators (Chapter 1). I addressed whether floral morphological differences of the related Silene species, S. caroliniana, S. virginica, and S. stellata, correspond to predicted specialized pollination systems (Chapter 2). I asked whether contemporary selection pressures on floral traits were detectable in a population of S. virginica (Chapter 3). I investigated the non-obligate interaction of S. stellata and the moth Hadena ectypa, that pollinates it and uses its immature seed for the development of larval offspring (Chapter 4). Using my novel methodology (Chapter 1), I demonstrated that S. virginica and S. stellata were specialized on hummingbirds and nocturnal moths, respectively (Chapter 2). S. caroliniana was least specialized with long-tongued diurnal hawkmoth (Hemaris sp) and large bee pollinators (Bombus spp. and Xylocopa virginiana). These results matched predictions based on interspecific differences in Silene floral trait expression and were consistent with the notion that the important pollinators are the major selective agents on floral design. Positive directional but mainly nonlinear hummingbird-mediated phenotypic selection (Chapter 3) on S. virginica floral traits was detected through lifetime fitness components, supporting predictions from the syndrome concept. Flowering date predicted the relative density of H. ectypa and other moth pollinators of S. stellata, and H. ectypa density varied by population and year, which may determine the sign of the H. ectypa-S. stellata interaction. Both curvature and directional selection in S. stellata's floral trait selection surface were context dependent on the intensity of H. ectypa larval fruit predation. Overall pollinators are important sources of selection underlying floral evolution in these Silene, and S. stellata floral evolution is subject to additional selection pressures from H. ectypa larvae.en_US
dc.format.extent1805304 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/8466
dc.language.isoen_US
dc.subject.pqcontrolledBiology, Ecologyen_US
dc.subject.pquncontrolledPollination syndromesen_US
dc.subject.pquncontrolledPollinator importanceen_US
dc.subject.pquncontrolledPollinator-mediated selectionen_US
dc.subject.pquncontrolledNursery pollinationen_US
dc.subject.pquncontrolledPollinator specializationen_US
dc.titlePOLLINATOR SPECIALIZATION AND THE EVOLUTION OF POLLINATION SYNDROMES IN THE RELATED SILENE, S. CAROLINIANA, S. VIRGINICA, AND S. STELLATAen_US
dc.typeDissertationen_US

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