<p> Evolutionary biologists are supremely interested in the events that cause populations to diverge and speciate, and the mechanisms that maintain divergence over time. Here, I investigate the evolutionary history of a boreal bird species complex. Boreal bird species are co-distributed, diverged during the Pleistocene, and generally have patterns of genetic divergence that are consistent with a single &ldquo;boreal&rdquo; clade in northern and eastern North America. The Gray-cheeked Thrush species complex, however, shows a possible species break in eastern North America between the Bicknell&rsquo;s Thrush (<i> Catharus bicknelli</i>) and Gray-cheeked Thrush (<i>Catharus minimus </i>). Using population genetic and genomic analyses of the largest sampling to-date of either species, I find that the eastern break indeed coincides with a species-level divergence, although low levels of admixture in a few individuals and one probable hybrid hint at the possibility of occasional hybridization. Species distribution models (SDMs) of the Last Glacial Maximum revealed that divergence may have been maintained by residence in different late-Pleistocene refugia. However, because speciation occurred mid-Pleistocene, I examined the geographical context of divergence of the Bicknell&rsquo;s Thrush and Gray-cheeked Thrush using multivariate analyses and ecological niche modeling techniques of local-scale habitat data and broad-scale climate and tree species distributions. Local-scale habitat analyses reveal that the thrushes breed at sites with unique tree species composition, physiognomy (forest structure), and ground cover characteristics; furthermore broad-scale analyses reveal that niche divergence, rather than conservatism, was the predominant pattern for these species, suggesting that ecological divergence has played a role in their speciation. This dissertation supports the hypothesis that the Bicknell&rsquo;s Thrush and Gray-cheeked Thrush are distinctive species that breed in divergent local- and broad-scale niches and emphasizes that this species-level divergence seems unique among boreal bird species.</p>

<p> Culverts are ubiquitous in urban and natural environments, installed to provide road access and erosion control, but often impact fish movements in freshwater habitats. Effects of culverts on marine and estuarine fish are not well-studied. This study aimed to understand the potential impacts of a culvert, which connects a large tidal bay and a coastal lagoon, on the movements of several species of fish. Habitat characteristics of both sites were analyzed to better understand these movements, including water parameters, sediment characteristics, and zooplankton, benthic macroinvertebrate, and small fish communities. The two habitats differed in terms of temperature, salinity, dissolved oxygen, zooplankton abundance, and community composition of zooplankton, benthic macroinvertebrates, and small fish. The culvert and associated grate limited large fish from moving between the two habitats likely due to body size and other morphological characteristics. Removing this barrier and replacing it with an open channel would increase connectivity between these two habitats which could improve trophic quality in the lagoon habitat and increase functionality overall.</p><p>

<p> Information about population dynamics, life history variation, and connectivity patterns of threatened cutthroat trout (<i>O. clarkii</i> spp.) is critical for effective management and restoration. The Lahontan cutthroat trout (<i>O. c. henshawi;</i> LCT) is classified as threatened under the Endangered Species Act due to widespread extirpations across its range, and is at increased risk due to drought, habitat fragmentation, and climate change. This study was conducted in the Summit Lake Basin, NV (USA), which has a population of LCT that resides in Summit Lake and its tributary stream network. The objectives of this research were to (1) examine the population dynamics of stream- and lake-dwelling LCT in the context of drought, (2) quantify the amount of stream-resident versus adfluvial life histories in an adfluvial spawning tributary, and (3) identify the level of population connectivity between stream-resident and adfluvial components of the population. Chapter 1 shows that stream-dwelling trout were more resilient to drought disturbance and that drought refugia in the stream contribute to their resilience. Chapter 2 provides evidence for stream-residency in addition to high population connectivity across the lake and stream environments that is likely to increase in high flow years. While LCT and other cutthroat species have innate characteristics that allow them to persist in dynamic and harsh environments, this research highlights the importance of drought refugia and landscape connectivity to the long-term persistence and viability of co-occurring adfluvial and stream-resident fish.</p><p>

<p> This study analyzes the range-wide genetic diversity and population structure of American hart&rsquo;s-tongue fern (<i>Asplenium scolopendrium</i> var. <i>americanum</i>, AHTF), a rare fern species in the eastern United States. AHTF populations from New York, Michigan, Alabama, Tennessee, and Canada are examined using combined simple-sequence repeat and inter-simple sequence repeat markers. Genetic data provide insights on levels of genetic diversity, population structure, genetic differentiation, gene flow, total allele frequency, number of rare alleles, linkage disequilibrium and mating system. Overall, three main genetic clusters were identified, which are represented by: 1) populations from NY; 2) all three populations from Canada and the rest of the populations from the U.S.; and 3) the commercially available hart&rsquo;s-tongue fern. Genetic data is utilized to designate Evolutionary Conservation Units, Management Units and Relevant Genetic Units, particularly for the U.S. populations. This study recommends seven populations as priority for conservation and management in the U.S.</p>

Thesis (M.S.)--University of Montana, 2008. / Title from title screen. Description based on contents viewed May 12, 2009. Includes bibliographical references (p. 131-134).

Thesis (Ph. D.) -- Lincoln University, 2009. / Also available via the World Wide Web.

Made available in DSpace on 2017-07-10T14:38:30Z (GMT). No. of bitstreams: 1 Dissertacao - adriane (pdf).pdf: 931863 bytes, checksum: 9362d32483efab607a95a16a4db0a7fd (MD5) Previous issue date: 2016-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Stress is an adaptive component that allows the fish to deal with various stressful events that occur during the life cycle of fish, such as the reproductive migration that demands physical efforts. The aim was to assess whether the steps for implementation to fish in the reservoir dam is promotes stress in curimba (Prochilodus lineatus). Adult fish species were sampled in March 2015 at three sites in the Hydroelectric Powerplant of Porto Primavera, Upper Paraná River, Brazil: downstream, the fish ladder and upstream of the dam, totaling 48 individual. Variations in body weight, standard length, and determination of plasma concentrations of cortisol, glucose, lactate, choloride and hematocrit they were analyzed in relation to gender and local sampled. The body weight and standard length presented comparable values for each location between genders, but the averages of females were significantly higher. Significant increase in plasma levels of glucose and lactate were observed but without significant changes in cortisol, chloride levels, as well as in hematocrit. The intense exercise of the fish by the transposition of fish ladder represented moderate stressor, without causing harmful effects to these animals, since the recovery of fish at the upstream from the dam. These results are deepening about the physiology used as a tool for conservation by providing knowledge and subsidies for the conservation and management of migratory species. / Resumo O estresse é um componente adaptativo que permite ao peixe lidar com eventos estressores que ocorrem durante o ciclo de vida dos peixes, como, por exemplo, a migração reprodutiva que exige esforço fisiológico dos animais. O objetivo do trabalho foi avaliar, por meio de indicadores fisiológicos, se a transposição de escada para peixes em barragem de reservatório representa um evento estressor para o curimba (Prochilodus lineatus). Peixes adultos da espécie foram amostrados em março de 2015 em três locais na Usina Hidrelétrica de Porto Primavera, Alto Rio Paraná, Brasil: a jusante, na escada para peixes e a montante da barragem, totalizando 48 indivíduos. Variações do peso corporal, comprimento padrão e das concentrações plasmáticas de cortisol, glicose, lactato, cloreto e hematócrito foram analisadas em relação ao gênero e local amostrado. O peso corporal e o comprimento padrão apresentou valores similares em todos os locais de coleta, nos dois gêneros, porém as fêmeas foram significativamente maiores a montante. Aumento significativo nos níveis plasmáticos de glicose e lactato foram observados, mas sem alterações significativas das concentrações circulantes de cortisol, cloreto e do hematócrito. O exercício intenso dos peixes pela transposição da escada para peixes representou uma condição moderadamente estressante, sem causar prejuízo biológico, visto a recuperação observada a montante. Estes resultados são aprofundamentos sob a fisiologia utilizada como ferramenta para conservação fornecendo conhecimento e subsídios para a conservação e manejo de espécies migratórias.