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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 43 for “"Outcrossing"”.
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Using molecular genetic techniques to detect outcrossing in natural populations of a self-fertilizing fish
… parents were homozygous; thus, no detectable outcrossing has occurred in these populations. However, DNA fingerprinting revealed segregation of markers among the offspring in 25 of 30 Belize Cay broods. Twenty-four of these broods were from the island of Twin Cays. An average of 30% of the …
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Evidence For Reduced Hawkmoth Pollination in Ruellia Humilis
… were used to estimate the historic and current outcrossing rates of four Missouri populations of self-compatible Ruellia humilis in order to assess whether there has been a recent reduction in hawkmoth-mediated outcrossing. The study sites represented both glade and prairie habitat fragments …
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Risk assessment of the transfer of imazethapyr herbicide resistance from Clearfield rice to red rice
Potential outcrossing between Clearfield rice and red rice will have a direct impact on the management and long-term usefulness of imazethapyr technology for rice weed control. The principal objective of this research was to determine the rate and agronomic consequences for outcrossing between …
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Characterizing Deleterious Genomic Mutations in Simulated Populations Under Some Biologically Realistic Situations
… are infinite with unlinked loci, completely outcrossing or selling, and at mutation-selection (M-S) balance. However, the population sizes of many organisms are not large enough to be considered infinite. In many plant and animal populations, selfing or outcrossing is often incomplete in that …
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Evolutionary dynamics of mating systems in populations of North American Arabidopsis lyrata
… systems from completely inbreeding to completely outcrossing, with intermediate forms referred to as mixed mating systems. Arabidopsis lyrata is a strongly outcrossing perennial due to a sporophytic self incompatibility (SI) system. The species occurs in temperate regions of the Northern …
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Population genetics of South African Protea L. (Proteaceae) species associated with various pollinator guilds
… mammals. Comparative estimates of pollinators’ outcrossing abilities are rare and confined to bird and insect guilds. Furthermore, 10 microsatellite markers have been developed for the genus, but have not been used to assess the outcrossing abilities of various pollinators. This study thus had …
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Breeding System, Heterozygosity, and Seed Germination in a Population of Missouri Bladder-Pod, Lesquerella Filiformis Rollins
… multilocus and single-locus estimates of the outcrossing rate (tm=1.000, ts=0.996) indicate a primarily outcrossing species. Among viable seeds, the smaller seeds were more prone to germinate. However, neither seed size nor germination behavior was related to multilocus or single-locus …
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The Influence of Biogeography and Mating System on the Ecology of Desert Annual Plants
… strategies in co-occurring selfing and outcrossing desert annuals. Firstly, I tested the abundant center model to determine the role of range position on plant population dynamics. I examined how the geographic and climatic position of 13 desert annuals found at a common location, the …
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The biosystematics of pteridophytes: aspects of morphology and reproductive biology of some epiphytic ferns
… to produce antheridia, thus promoting outcrossing;Genetic load indicates that L. thunbergianus, M. heterophylla, P. pellucidum, E. alatum, E. callifolium, E. crassifolium and one source of C. angustifolium produce sporophytes mainly through intergametophytic mating whereas P. aureum, P. …
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The reproductive biology of Clematis addisonii
… onset of anthesis enhances the probability that outcrossing will occur prior to the presence of self-pollen in flowers. These findings suggest that, in spite of self-compatibility, populations of <i>Clematis addisonii</i> are capable of maintaining high levels of outcrossing by virtue of …
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Moth pollination, low seed set, and vestigialization of attractive floral traits in Abronia umbellata (Nyctaginaceae)
… from self-incompatibility and obligate outcrossing to self-compatibility and predominant selfing is the most common evolutionary transition among the flowering plants and traits associated with outcrossing may become reduced across such shifts, potentially through the action of natural …
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Evolution of floral and mating system variation in Camissoniopsis cheiranthifolia (Onagraceae): An evaluation of patterns and processes
… with variation in the relative importance of outcrossing vs. self-fertilization. I combined geographic surveys of floral variation with genetic estimates of the proportion of seeds outcrossed (t) and confirmed that t covaried with corolla width and herkogamy in a predictable way both within …
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Inbreeding Depression in the Partially Selfing Perennial, Ruellia Humilis
… by showy chasmogamous flowers that promote outcrossing via hawkmoths and automatically self-fertilizing cleistogamous flowers which have ensured a long history of partial selfing. Previous studies have indicated a loss of hawkmoth pollination in isolated populations of Southwest Missouri …
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The Phenotypic Impact of Transgenic Flower Color Variation in Ipomoea quamoclit.
… and fruit and seed traits were recorded. An outcrossing experiment was performed to examine differences in pollen and ova fitness between the color morphs.</p> <p>The single genetic change to create blue-flowering <em>I. quamoclit</em> resulted in changes in almost every trait measured. …
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Regulation of reproductive success in the biennial plant, Hydrophyllum appendiculatum
… (Hydrophyllaceae), a biennial, self-compatible, outcrossing, insect-pollinated, forest understory herb. Observations conducted in two populations over three flowering seasons (1987-1989) revealed that survival, flower production, and seed production varied spatially and temporally. While some of …
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Distribution of chemistry and sexual fecundity in the lichenized-fungi, Xanthoparmelia cumberlandia and Xanthoparmelia coloradoensis on Boulder Mountain, Aquarius Plateau, UT
… of rare chemicals and chemotypes implies that outcrossing is more common at the upper elevation. Since these indicators lead to opposing conclusions, we encourage the use of molecular markers to estimate the frequency of outcrossing directly.</p>
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Characterization of Transgenic Peanuts Expressing Oxalate Oxidase for Governmental Approval of Their Release for Control of Sclerotinia Blight
… blight and yield under disease pressure. Outcrossing studies were completed to determine the rate and distance of cross pollination. Outcrossing rates in N70, P39 and W171 were less than 2.5% and occurred up to 19 rows or 17.4 m from the nearest transgenic row. The molecular …
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Development of the Limb in Mice Bearing the Mutant Gene: Hypodactyly (Hd).
… the new mutant, Hypodactyly was transferred by outcrossing to unrelated normal animals for study of its inheritance and expression. Hypodactyly was inherited as a semi-dominant mutation with full penetrance. No maternal or paternal influences were noted. The homozygotes, which were inviable, …
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Impact of self-fertilization on fecundity, the timing of first reproduction, and population genetic structure: Is a mate worth the wait?
… preferential selfing (mean: 0.801), though some outcrossing appears to take place. Population genetic structure indicates populations are disjunct and characterized by low levels of gene flow. Our results reveal P. americanus exhibits an interesting suite of life-history traits, uniting high …
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Allozyme Diversity and Hybridization in Castanea Pumila (Section Balanocastanon, Fagaceae)
Castanea pumila is an outcrossing, woody perennial native to the Southeastern United States. Once considered separate species, C.pumila var. ozarkensis (the Ozark Chinquapin) and C. pumila var. pumila were recently combined due to extensive morphological intergradation. One explanation for the …
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