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 17 of 17 for “"secondary contact"”.
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Diversification of Antbirds Associated with Amazonian Flooded Forest Habitats
… consistent with either parapatric divergence or secondary contact, Sclateria exhibited strongly concordant cline centres across nuclear loci, mitochondrial DNA and female plumage, consistent with secondary contact between an eastern and western lineage that diverged in allopatry. I also applied …
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Mechanisms for partial reproductive isolation in a Bombina hybrid zone in Romania
… to reproductive isolation in the case of secondary contact. Hybrid zones are ideal study systems in which to investigate mechanisms for the inhibition of gene flow. This thesis describes a mosaic hybrid zone between the ecologically differentiated fire-bellied toads Bombina bombina and B. …
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Genetic Divergence Among Subspecies of Basilarchia Arthemis
… with a common pattern of post-Pleistocene secondary contact between sister taxa of a variety of organisms, notably the tiger swallowtail butterflies Papilio glaucus L. and P. canadensis Rothschild and Jordan. The data suggest a greater level of divergence between arthemis and astyanax than …
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SPECIES RECOGNITION IS DRIVING EVOLUTION OF THE ACOUSTIC MATING SYSTEM OF SHIELD BACK KATYDIDS (ORTHOPTERA: TETTIGONIIDAE: AGLAOTHORAX): BEHAVIORAL AND PHYLOGENETIC EVIDENCE
… shown for the species coexisting in response to secondary contact, results consistent with species recognition.
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Allozyme Diversity and Hybridization in Castanea Pumila (Section Balanocastanon, Fagaceae)
… indicate a broad cline characteristic of secondary contact. This pattern could reflect the presence of an old hybrid zone, but is inconsistent with the presence of two reproductively-isolated groups. Consequently the data support the recent revision of the section.
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Mating Habits, Dispersal and Postglacial Range Expansion of Nigronia Serricornis (Say) (Megaloptera: Corydalidae)
… Carolina along the coast to Maine. Points of secondary contact were identified in New York and Ohio. The remaining clades showed no significant phylogeographic relationship according to the NCPA. The distribution of one of these clades, however, followed pre-glacial drainages. Fragmentation …
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Adaptation and hybridization in Helicoverpa crop pests
… process of biological invasion often results in secondary contact between closely related taxa, producing ‘experiments in evolution’. Evolutionary genetics can be used to study invasive species and inform their management. In this thesis I focus on noctuid crop pests in the genus Helicoverpa, …
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Cellular/Molecular Analysis of Interspecies Sterile Male Hybrids In Drosophila
… gene flow between the populations and, upon secondary contact, result in distinct species. The process of speciation is, thus, what accounts for the multitude of species that contribute to the rich biodiversity on Earth. Interspecies hybrid sterility is a postzygotic isolating mechanism that …
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Phylogeographic analysis reveals strong geographical structuring in the klipspringer, Oreotragus oreotragus
… late Pl iocene/early Pleistocene, after which secondary contact occurred and klipspringer moved upwards from southern Africa to colonise the east. The results from this study have conservation implications with respect to translocation policies, suggesting that translocations should only occur …
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Hybrid zone genetics and within-island diversity of the gecko Tarentola boettgeri
… structuring of mtDNA has been maintained after secondary contact. MtDNA analyses used a 608 basepair fragment of the cytochrome b (cyt b) gene from 389 individuals sampled from 14 populations along a 32 km southeast (SE) transect across Gran Canaria. It revealed a low degree of mtDNA admixture …
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Análise da estrutura genética populacional da piraúna (cephalopholis fulva: serranidae) ao longo da costa e ilhas oceânicas brasileiras
… the sampled spots. The indices h and indicate a secondary contact between previously allopatric lineages differentiated or large and stable populations with long evolutionary history. Tests of Tajima and Fu showed expansion for all populations. In contrast, the mismatch distribution and SSD …
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Y chromosome and allozyme correlates of geotaxis in selected lines of Drosophila melanogaster and their hybrids
… an experiment that examines an outcome of secondary contact of the selected geotaxis lines that have had independent evolutionary histories since 1958. Individuals from lines derived from the hybridization of selected geotaxis lines were tested for geotaxis and assayed for alcohol …
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HSPF Modeling of Nonpoint Sources in Tickfaw River Watershed
… section 303(d), outstanding natural resource and secondary contact recreation designated uses are fully supported, but fish and wildlife propagation and primary contact recreation are not supported. According to the 303(d) list, the impairments in Tickfaw River are mercury, total dissolved solids, …
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Is meadowlark habitat segregation within sympatry behaviorally mediated?
… that co-occur within a recently expanded zone of secondary contact. Although spatial patterns of sympatric meadowlark populations have been previously compared, these comparisons have been qualitative in nature and lack the quantitative evidence necessary to provide a rigorous understanding of …
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Genetics, demography and modeling of freshwater mussel (Bivalvia: Unionidae) populations in the Clinch River, U.S.A.
… diverged mtDNA lineages, perhaps indicative of secondary contact, were observed in E. brevidens and E. capsaeformis. High levels of gene flow (Nm) were estimated among demes of L. fasciola using traditional F-statistics and likelihood estimates of Nm, whereas such metrics were lower in E. …
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Comparative Population Genomics and Speciation of Snakes Across the North American Deserts
… (a) strict isolation, (b) divergence with secondary contact, and (c) divergence with continuous gene flow. Results from this study suggest that all populations identified via clustering methods represent distinct species with non-concordant contact zones across each species group. In …
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Evolution in Neotropical Herpetofauna: Species Boundaries in High Andean Frogs and Evolutionary Genetics in the Lava Lizard Genus Microlophus (Squamata: tropiduridae): A History of Colonization and Dispersal
… of multi-locus non-coding DNA data sets. A secondary finding in this study is that mtDNA and nDNA topologies are discordant with each other but that both are strongly supported, and that the nuclear topology is concordant with species distribution patterns along coastal South America. We …