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dc.contributor.authorJohnston, Jill Arin
dc.date.accessioned2014-03-05T16:06:49Z
dc.date.available2014-03-05T16:06:49Z
dc.date.issued2002-05
dc.identifier.otherjohnston_jill_a_200205_phd
dc.identifier.urihttp://purl.galileo.usg.edu/uga_etd/johnston_jill_a_200205_phd
dc.identifier.urihttp://hdl.handle.net/10724/29556
dc.description.abstractMounting evidence suggests that hybridization between species is more common and more important to plant evolution than was previously believed by evolutionary biologists. This body of research addresses the physiological changes that occur in hybrids between Iris brevicaulis and I. fulva, and the ecological and evolutionary implications of that change. In a series of experiments in the field and greenhouse, I have documented that hybrids live in a different range of habitat than their parent species, and are capable of outperforming parent species in some habitats. The ability to survive in different habitat conditions is attributed to new trait combinations in recombinant hybrid individuals. Explicit tests of flood, drought, and shade tolerance indicate that some hybrid individuals are more tolerant of flooded conditions, but I. brevicaulis is superior in dry conditions, and I. fulva is superior in the shade. Physiological traits measured on parent species and hybrid individuals were quite similar, and not adequate to explain the observed patterns of relative hybrid fitness. By transplanting both species and several hybrid types into natural habitat in the field, I was that both vegetative and sexual fitness of hybrid individuals was higher than that of both parent species in flooded, I. fulva-like habitat, and equivalent to parent species in other habitats tested. Comparisons of seed and adult stage fitness in both field and greenhouse conditions indicate that hybrids and parent species have fairly equivalent fitness at the seed and seedling stage, while adult fitness of hybrid groups is more variable, and more responsive to the environment. Overall, this work suggests that hybrids in natural populations of I. brevicaulis and I. fulva are important sources of new genetic and phenotypic variation. Hybrids have likely played a large role in shaping the ecology and physiology of the species, and will continue to do so through introgression and ecological divergence of hybrids.
dc.languageThe effects of hybridization on the physiology and ecology of two louisiana iris species, I. brevicaulis and I. fulva
dc.publisheruga
dc.rightspublic
dc.subjectIris
dc.subjectLouisiana
dc.subjectHybridization
dc.subjectHybrid fitness
dc.subjectPlant Evolution
dc.subjectPlant physiology
dc.subjectPlant ecology
dc.titleThe effects of hybridization on the physiology and ecology of two louisiana iris species, I. brevicaulis and I. fulva
dc.typeDissertation
dc.description.degreePhD
dc.description.departmentBotany
dc.description.majorBotany
dc.description.advisorLisa A. Donovan
dc.description.advisorMichael L. Arnold
dc.description.committeeLisa A. Donovan
dc.description.committeeMichael L. Arnold
dc.description.committeeJim Hamrick
dc.description.committeeShumei Chang
dc.description.committeeChris Peterson
dc.description.committeeRebecca Sharitz


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