Global ETD Search
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 11 of 11 for “"prezygotic"”.
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Female Preference and Prezygotic Isolation In the Fundulus Notatus Species Complex
<p>Understanding how reproductive isolation arises between closely related species is central to evolutionary research. Hybridization is widespread across taxa and shaped by interactions among environmental factors, evolutionary history, genetic compatibility, and behavior. These forces often …
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The evolution of prezygotic reproductive isolation in the Drosophila pseudoobscura subgroup
… dissertation is to evaluate some mechanisms of prezygotic reproductive isolation in the D. pseudoobscura subgroup. I begin by evaluating how the evolution of female preferences and male sexual characters lead to reinforcement between Drosophila pseudoobscura and its congener D. persimils. In …
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Investigation of multiple interspecific reproductive barriers in Solanum section Lycopersicon
… plants; IRBs occurring before mating (premating prezygotic barriers), those operating after mating but before fertilization (postmating prezygotic barriers), and those acting after fertilization (postzygotic barriers). In the tomato clade, postmating prezygotic barriers regulating pollen tube …
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How Are Rare Species Maintained?: Reproductive Barriers Between Layia jonesii, a Rare Serpentine Endemic, and L. platyglossa
… of reproductive barriers. I hypothesize prezygotic reproductive isolation in this system is due to (1) habitat isolation due to local adaptation to differential edaphic environments on the hillside, (2) flowering time differences, and (3) reduced seed set resulting from hybrid crosses. To …
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The origins and maintenance of species boundaries in Jamesbrittenia O. Kuntze (Scrophulariaceae: Manuleae)
… were calculated using a relaxed clock method. Prezygotic isolation, measured as seed set resulting from interspecific crosses, correlated with divergence time. However, recently diverged, highly sympatric taxa deviated from the overall trend. This provides circumstantial evidence for …
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Association of Polymorphic Blood Group Systems and Relative Fitness in Pigs
… in the K system. There was evidence for prezygotic selection (meiotic drive) in the B system. The method of maximum likelihood was used to estimate relative fitness of blood group genotypes from segregation data where a consistent heterotic effect was obtained in the H system with …
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Behaviour and morphology of the zebrafish, danio rerio
… made in elucidating the mechanisms underlying prezygotic isolation. A full understanding requires a knowledge of underlying genetics. To date the only real progress has been made using Drosophila: more model organisms are needed. It is proposed that the zebrafish, Danio rerio, a species well …
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Mechanisms and consequences of hybridisation between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)
… been done to investigate the way postcopulatory, prezygotic mechanisms act to isolate species at the level of the gamete. This thesis uses the naturallyhybridising, externally-fertilising system of Atlantic salmon, Salmo salar, and brown trout, S. trutta, to investigate mechanisms of hybridisation …
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Hybridization Between Amaranthus Tuberculatus and Amaranthus Hybridus
… (A. tuberculatus as female) were obtained, and prezygotic reproductive barriers appeared to be limited mostly to pollen availability/competition. All F1 hybrids were dioecious and sex segregation was consistent with postulated chromosomal XY-type system, with males as the heterogametic sex. …
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Adaptation and hybridization in Helicoverpa crop pests
… million years ago and show strong but incomplete prezygotic reproductive isolation. As a consequence of hybridization, an allele conferring insecticide resistance was introduced into the native Brazilian H. zea population through adaptive introgression. I use this as a system with which to …
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The genetics of species differences within the genus Nasonia ASHMEAD 1904 (Hymenoptera: Pteromalidae)
… traits are supposed to be frequently involved in prezygotic isolation, i.e. they prevent the formation of hybrids, whereas postzygotic isolation occurs when hybrids experience a fitness reduction. The parasitic wasp genus Nasonia represents an appropriate model system to investigate the genetics …