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 16 of 16 for “"Reproductive barriers"”.
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Investigation of multiple interspecific reproductive barriers in Solanum section Lycopersicon
Interspecific reproductive barriers (IRBs) act to prevent hybridization between close relatives and provide insight on how species maintain their integrity in nature. Wild tomato species (Solanum Section. Lycopersicon) are useful for studying IRBs. The monophyletic tomato clade includes 13 closely …
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How Are Rare Species Maintained?: Reproductive Barriers Between Layia jonesii, a Rare Serpentine Endemic, and L. platyglossa
<p>Reproductive barriers are vital to generating new species as well as maintaining distinct species. Investigating reproductive barriers between closely related plant taxa helps us to understand how these barriers are maintained, particularly between rare and widespread relatives. <em>Layia …
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Investigation of pre- and post-zygotic reproductive barriers between two host-plant complex races of the parasitic wasp Cotesia congregata (Say) [Hymenoptera: Braconidae]
Investigations of host-associated differentiation of parasitoids have largely focused on the degree of molecular genetic differentiation, but a true test of species status must examine the mating patterns of differentiated populations to determine if they can interbreed in the wild and produce …
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The genetic basis of reproductive isolation in house mice: Studies of a European hybrid zone
… patterns that characterize the genetic basis of reproductive isolation. First, reproductive isolation is usually caused by incompatible substitutions at different, interacting loci. Second, the locations of genes contributing to reproductive isolation are biased toward the X chromosome. These …
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Decline of the Savannah River Redeye Bass (Micropterus Coosae) Due to Introgressive Hybridization With Invasive Alabama Spotted Bass (Micropterus Punctulatus Henshalli)
… especially in species that have limited reproductive barriers, i.e. icthyofuana. Here hybridization is examined between two introduced species (Alabama spotted bass, Micropterus punctulatus henshalli, and smallmouth bass, M. dolomieu) and two endemic species of black bass (redeye bass, M. …
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Morphological Variation and Community Science in Orthoptera
… ranging species, and the importance of studying reproductive barriers in more than one or two transects of a hybrid zone.</p>
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The origins and maintenance of species boundaries in Jamesbrittenia O. Kuntze (Scrophulariaceae: Manuleae)
… being explored. Speciation patterns and reproductive isolation were investigated in order to identify trends that may apply at broader scales. Bayesian phylogenetic analysis was performed using plastid (rps 16 and psbA-trnH) and nuclear (GScp) sequence data. Relative divergence times were …
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Hybrid zone genetics and within-island diversity of the gecko Tarentola boettgeri
… contact zone. This led to the hypothesis that reproductive barriers may have formed between populations from different mtDNA lineages. Analyses of seven body dimension and scalation characters revealed that spatial patterns of morphological changes were not associated with the transition in …
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The genomic basis of species barriers in Heliconius butterflies
… can elucidate the genetic architecture of reproductive isolation and, ultimately, the process of speciation. Hybridization between two species is often maladaptive and results in offspring with decreased fitness compared to the parental forms. Recently, with the development of molecular and …
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Hybridization Between Amaranthus Tuberculatus and Amaranthus Hybridus
… 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. Chapter Four …
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Neural Circuit Mechanisms Underlying Behavioral Evolution in Drosophila
<p>Courtship rituals serve to reinforce reproductive barriers between closely related species. Several species in the Drosophila melanogaster subgroup exhibit pre-mating isolation due, in part, to the fact that D. melanogaster females produce 7,11-heptacosadiene (7,11-HD), a pheromone that promotes …
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The Convoluted Origin and Diversification of Strangler Figs in the Neotropics
… Ficus in Cuba is reinforcement of postzygotic reproductive barriers. Finally, in chapter three, I present the first draft genome of a strangler fig, F. velutina (sect. Americanae). I combined DNA reads from three sequencing platforms (PacBio Sequel II, Nanopore MinIon, and Illumina Miseq). With …
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Mating costs and gametic barriers to reproduction
… individuals involved, or may affect their future reproductive output, are not often quantified. I assess costs that are acquired at different periods of the mating process–in search of a mate and gametic interactions after copulation. I first quantify the cost of mate searching of a monogynous …
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Testing the utility of the consortium for the barcoding of life's two 'agreed upon' plant DNA barcodes, matK and rbcL
… lineages. This is in large part due to poor reproductive barriers, which allows for chloroplast sharing between closely related species. In the summer of 2009, the Consortium for the Barcoding of Life‘s Plant Working Group (CBOL, PWG) announced that portions of two coding chloroplast gene …
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Intra-species genomic variations in hydrogen-oxidising bacteria is delineated by horizontal gene flow
… species are traditionally defined through reproductive isolation, where reproductive barriers result in adaptive traits being shared only within the isolated population. Therefore, discontinuities in gene flow in eukaryotes generally result in the formation of an ecologically and …
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Cytogenetics and genome structure in genus Miscanthus, a potential source of bioenergy feedstocks
… to generate superior germplasm and to circumvent reproductive barriers for the introduction of new genetic variation into core germplasm. Therefore, synthetic autotetraploid lines of M. sacchariflorus and M. sinensis, and autoallohexaploid M. x giganteus were produced in tissue culture from …