Thesis (M.Sc.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 25-31). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR45945

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 99-118).

Thesis (M.S.)--Montana State University--Bozeman, 2005. / Title from PDF t.p. (viewed on June 10, 2006). Chairperson, Graduate Committee: Richard J. Aspinall. Includes bibliographical references (p. 93-105).

The typical intermediate morphology of hybrids may result in their failure to utilize the same niches as their parents. However, the fitness consequences of the potentially intermediate life-history traits of hybrids have been given less scientific attention. In this study I aimed to investigate how life-history divergence in parental species affects the relative fitness of nestling hybrids resulting from crosses between collared (Ficedula albicollis) and pied flycatchers (F. hypoleuca). Previous studies showed that collared flycatcher nestlings beg more intensively and grow faster under good conditions, but are less robust against the seasonal decline in food availability compared to pied flycatcher nestlings. This life-history divergence between the species allows regional coexistence. To investigate whether the life-history divergence in flycatchers influences the relative fitness of nestling hybrids, I cross-fostered hybrid nestlings in aviaries into the nests of conspecific pairs and compared their performance. I found that the hybrids displayed intermediate growth rates between collared and pied flycatchers across the season. There might therefore be environmental conditions when hybrids perform better than purebred offspring with respect to growth and survival.

No description available.

Thesis (Ph. D.)--University of Montana, 2006 / Title from PDF title page (viewed on Mar. 18, 2007). Includes bibliographical references.

I studied the nest-site selection of the Acadian Flycatcher (Empidonax virescens) in the George Washington National Forest of southwestern Virginia from early May through July 1996 and 1997. Data were collected from nine 30 ha study plots. I measured habitat features at 37 Acadian Flycatcher nests and compared them to 30 nonuse sites randomly selected within the vegetation types associated with nests. Because Acadian Flycatchers have a strong riparian habitat association for nest-site selection, nonuse sites were established along riparian corridors not occupied by nesting flycatchers. Data also were collected to determine relationships between microhabitat characteristics and nesting success of the Acadian Flycatcher. Nest-sites were associated with a more mature or climax community, as evident from the high percentage (75%) of nests in eastern hemlock (Tsuga canadensis), a climax community tree species and the greater basal area found at nest-sites over nonuse sites. Nest-sites also had lower small stem density and ground cover than nonuse sites. Nest-sites were always found near streams, although I found no conclusive evidence that any stream characteristic influenced nest-site selection. Habitat features did not differ between successful and depredated nests. Brood parasitism by Brown-headed Cowbirds (Molothrus ater) was not a major factor in the reproductive success of Acadian Flycatchers (only a 2% parasitism rate); depredation accounted for the majority of nest failures. These results suggest that silviculture activities near riparian corridors could drastically reduce habitat availability and subsequently contribute to population declines of the Acadian Flycatcher. Future research should focus on determining the size of riparian buffer strips needed to retain this species along riparian corridors in the Appalachian Mountains. This strategy can be applied to the current downtown revitalization efforts by the City of Muncie. The ideas and general theories can also be applied by small Indiana towns which suffer from economic problems. A comprehensive plan that is tailored specifically for a downtown which account for the organization, design, economic, and promotion needs of downtown will set the course for successful commercial revitalization. / Department of Biology

This thesis investigates the ecological and evolutionary implications of a recent secondary contact between two closely related bird species: collared (Ficedula albicollis) and pied (F. hypoleuca) flycatchers. Collared flycatchers started to colonize the Swedish island of Öland, where pied flycatchers were already present, in the late 1950s-early1960s. My major aims were to investigate which factors are acting against versus for long-term coexistence between the two species. Specifically, I investigated the relative importance of allopatric divergence, interspecific competition, hybridization and learning in promoting or inhibiting coexistence. The combined effects of interspecific competition and hybridization drives pied flycatchers towards local extinction in their preferred deciduous habitat. However, my results also show that pied flycatchers are better able to tolerate harsh environmental conditions. This trade-off between competitive ability and resilience in the face of harsh conditions facilitates a regional coexistence between the species. Coexistence is furthermore favoured by competition-mediated divergence in breeding habitat choice, timing of breeding and male breeding plumage colouration. Due to interspecific competition, male pied flycatchers are forced to breed in a more mixed forest type with a later peak in food abundance, which is accompanied by a divergence in breeding time between the two species. In areas shared with collared flycatchers, male pied flycatchers with brown plumage coloration, most divergent from that of collared flycatchers, are favoured by selection. In addition to facilitating coexistence, the observed shift in habitat occupancy increases reproductive isolation between the two species. By using cross-fostering experiments I demonstrate that natal habitat imprinting has the potential to additionally speed up habitat segregation. Finally I show that hybrid nestlings express an intermediate response to harsh environments, indicating that another aspect of ecological-based selection may be important in reproductive isolation between the species. In summary, my results show that adaptations during historic allopatry are important both in facilitating coexistence as well as in providing a foundation for further ecological divergence at secondary contact. This is of relevance today as many species are shifting their distributions in response to habitat disturbance and global warming.

In order to get full understanding of how evolution proceeds in natural settings it is necessary to reveal the genetic basis of the phenotypic traits that play a role for individual fitness in different environments. There are a few possible approaches, most of which stem from traditional mapping efforts in domestic animals and other model species. Here we set the stage for gene mapping in natural populations of birds by producing a large number of anchor markers of broad utility for avian genetical research and use these markers to generate a genetic map of the collared flycatcher (Ficedula albicollis). The map reveals a very high degree of synteny and gene order conservation between bird species separated by as much as 100 million years. This is encouraging for later stages of mapping procedures in natural populations since this means that there is a possibility to use the information from already characterized avian genomes to track candidate genes for detailed analysis in non-model species. One interesting aspect of the low degree of rearrangements occurring in the avian genomes is that this could play a role in the low rate of hybridization barriers formed in birds compared to for instance mammals. An analysis of Z-linked gene markers reveals relatively long-range linkage disequilibrium (LD) in collared flycatchers compared to other outbred species but still, LD seems to decay within < 50 kb indicating that > 20.000 markers would be needed to cover the genome in an association scan. A detailed scan of 74 Z-linked genes evenly distributed along the chromosome in both the collared flycatcher and the pied flycatcher (Ficedula hypoleuca) indicates that there are regions that evolve under directional selection, regions that might harbor loci of importance for adaptive divergence and/or hybrid inviability.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 24, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Frank Thompson and Dr. Mickey Heitmeyer, Dissertation Supervisors. Vita. Includes bibliographical references.