Master of Science / Department of Biology / Kimberly A. With / Organisms exist within complex landscapes, and landscape features may influence multiple aspects of a species’ distribution within the landscape, including patch occupancy, abundance within patches, and population genetic diversity at a local or regional scale. We took two approaches to identify the relative importance of landscape context for populations of the Eastern Collared Lizard (Crotaphytus collaris collaris) in the northern Flint Hills of Kansas. First, we conducted surveys at limestone outcrops in experimental watersheds managed under different burning and grazing practices. Habitat occupancy and lizard abundance were estimated by constructing models that incorporated aspects of the environment at multiple scales. Both abundance and occupancy were higher on rock ledges that had more crevices, greater complexity in vegetation, covered a larger area, and were more prominent than available habitat. Abundance and occupancy were also higher in watersheds that were burned frequently (1–2 year intervals), but grazing only had a significant effect in less frequently burned (four–year burn interval) watersheds. Our second approach was to measure genetic diversity and population genetic differentiation and relate these measures to differences in landscape context. We sampled collared lizard DNA at four locations (sample sites < 45 km apart) and analyzed trends in 10 polymorphic microsatellite loci. We found evidence for low genetic variability and moderate population differentiation among our sample sites relative to estimates reported in the literature at the core of the species’ range. Differences in migration rates and ancestry among sampling locations also appear to correspond to differences in landscape resistance based on land cover and rock availability. Thus, it appears that habitat management may influence the suitability of habitat patches at the local scale, and that differences in land cover and rock availability may influence the connectivity of populations at the landscape scale.

Call number: LD2668 .T4 1986 M46 / Master of Science / Biology

xiv, 154 p. : ill. A print copy of this title is available through the UO Libraries. Search the library catalog for the location and call number. / The polychaete worm Owenia collaris (Family Oweniidae) is found in soft sediment habitats along the northeastern Pacific coast, particularly within bays and estuaries. Seasonally, these small tubeworms spawn gametes freely into the water column where they develop into planktotrophic mitraria larvae. After three to four weeks at ambient temperatures, they undergo a dramatic metamorphosis and return to the bottom. The reproductive and larval biology of a population of O. collaris in Coos Bay, OR was investigated over several years. The development of this polychaete has several unusual features, including a stomodeum not derived from the blastopore and continued proliferation of trochoblast descendents, producing simple cilia on monociliated cells. The description of larval and juvenile structures provided morphological characteristics useful for distinguishing this species from the congener O. fusiformis . The consequences of the unusual larval morphology of O. collaris (i.e. simple cilia, convoluted ciliated band) were investigated by comparing the feeding performance and growth of this species with those of invertebrate larvae representative of the more typical tornaria-type larval forms found in deuterostomes and trochophore-type larval forms found in the lophotrochozoa. Feeding and growth patterns were similar in the convergent mitraria and deuterostome larval forms. In an experiment designed to test the relationship between abiotic factors and the seasonal reproduction, the onset of breeding was cued by photoperiod, but seasonal trends in temperature, alkalinity, food availability for larvae, and salinity may drive reproductive patterns as well. Within the Coos Bay estuary, the intertidal distribution of O. collaris is related to adult salinity tolerances. Low salinity limits horizontal distribution and also reduces potential for reproduction. Most life-history stages are tolerant of a wide range of temperatures, both higher and lower than those typically seen in Coos Bay. There is little evidence to support the hypothesis that sediment characteristics limit distribution within the bay, although settling juveniles show some preference for small grain sizes and may not be able to recruit to mudflats that completely lack these size fractions.

No description available.

Neotyphodium are fungal endosymbionts of grasses that reproduce asexually by infecting the hosts seed. This relationship has traditionally been considered mutualistic, with the fungus improving host fitness by alleviating important stresses. To determine the importance of biotic and abiotic stresses in mediating the endophyte-grass interaction, I investigated the relationship between grazing pressure by collared pikas and Neotyphodium sp. infection frequency in the grass Festuca altaica in an alpine meadow. I conducted a factorial design experiment combining endophyte infection, grazing history, fungicide and fertilizer. Leaf demography and herbivory damage were monitored every two weeks. In areas with chronic grazing history, infected plants were significantly less productive than uninfected tussocks, but there was no difference at low grazing history. There was no effect of infection on the likelihood of herbivory. Contrary to predictions of the mutualism theory, the Neotyphodium sp. / F. altaica symbiotum varied from parasitic to neutral across our gradient of interest. / Ecology

Submitted by (edna.saturno@ufrpe.br) on 2016-11-24T14:00:56Z No. of bitstreams: 1 Fabiana Duarte Santos.pdf: 2371099 bytes, checksum: 1c8f25b2ef826a43434bb5853e061807 (MD5) / Made available in DSpace on 2016-11-24T14:00:56Z (GMT). No. of bitstreams: 1 Fabiana Duarte Santos.pdf: 2371099 bytes, checksum: 1c8f25b2ef826a43434bb5853e061807 (MD5) Previous issue date: 2006-02-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In Brazil, the presence and the increase of the population of grasshoppers are linked, certainly, to the deforestation and to the new types of manipulation of agroforestry cultures, implanted in the cerrado and other regions. Among the species of grasshoppers of economic importance, the Tropidacris collaris (Stoll, 1813) (Orthoptera: Romaleidae) is highlighted. Several morphological and histological studies of the female reproductive system of the insects have been reported as an important tool for phylogenetic relationship between the insect species. Thus, the present research had the objective of proceeding the morphometry of the ovary, quantifying the ovarioles, describing the histology of the female reproductive system, besides analyzing the ultrastructure of the ovarioles of the T. Collaris that were submitted to photoperiods of 10L:14D, 12L:12D and 14L:10D, in the last instar. The morphometric averages of the ovary and the quantification of the ovarioles were submitted to the Variance analysis. Thecollected organs were fixated in alcoholic Boüin, included in “paraplast”, dyed and analyzed under light microscopy. For the transmission and analysis of the electronic light microscopy, the ovarioles were fixated in Karnovsky. The results showed two stages of development of the pre-reproductive and the reproductive ovaries. There weren’t meaningful statistical differences for the morphometry related to length and width (side-lateral and dorsoventral) of the ovaries as well as the number of ovarioles, which were of 195.62, 202.62 and 208.25 for the photoperiods 10L:14E, 12L:12E and 14L:10E, respectively. The photoperiods also have not affected the histology of the organs and the ultrastructure of the ovarioles. Each of the ovarioles presented tubular morphology and three well characterized areas. The terminal fiber is constituted by connective tissue. In the germary, the ovogonias are in intense myotic activity and associated to the follicular cells. Each section of the vitelarium is internally covered by follicular cells, containing several ovocytes in different development stages. The lateral oviduct is covered bysimple cubic epithelial tissue with numerous folds, connective and muscular tissue. In the common oviduct the epithelium presents tunica intima and a well developed muscular layer. The spermatic duct is covered by columnar pseudo-stratified epithelial tissue with a thick tunica intima and two layers of muscular tissue, one longitudinal and the other circular, and between them, connective tissue. Ultrastructurally the ovarioles presented themselves as covered by a thick sheath, constituted by a homogenous and fibrous material. In the terminal filament, it has been observed cells with voluminous nuclei and scarce cytoplasm, besides an abundant extra cellular matrix with several filamentous structures. In the germary the ovogonias are bigger with voluminous nuclei, scarce cytoplasm and cellular membrane with interdigitation. The follicularcells are smaller, presenting cytoplasmatic projections. In the vitelarium, the follicular cellssuffer modifications in their morphology, varying from cubic to flat. / No Brasil, a presença e o aumento da população dos gafanhotos estão ligados certamente ao desmatamento e aos novos tipos de manejos de culturas agro-florestais implantadas no cerrado e outras regiões. Dentre as espécies de gafanhoto de importância econômica, destaca-se Tropidacris collaris (Stoll, 1813) (Orthoptera: Romaleidae). Vários estudos morfológicos e histológicos do aparelho reprodutor feminino dos insetos têm sido relatados como importante instrumento para relações filogenéticas entre as espécies de insetos. Assim, a presente pesquisa teve o objetivo de realizar a morfometria dos ovários, quantificar os ovaríolos, descrever a histologia dos órgãos do aparelho reprodutor feminino, além de analisar a ultraestrutura dos ovaríolos de T. collaris, submetido aos fotoperíodos de 10L:14E, 12L:12E e 14L:10E, no último instar. As médias da morfometria dos ovários e quantificação dos ovaríolos foram submetidas à Análise de Variância(ANOVA). Os órgãos coletados foram fixados em Boüin alcoólico, incluídos em "paraplast", corados e análise em microscopia de luz. Para a microscopia eletrônica de transmissão e varredura os ovaríolos foram fixados em Karnovsky. Os resultados mostraram dois estágios de desenvolvimento dos ovários pré-reprodutivos e reprodutivos. Não houve diferenças estatísticas significativas para a morfometria do comprimento e largura (látero-lateral e dorso-ventral) dos ovários, bem como do número de ovaríolos, que foi de 195,62; 202,62 e 208,25 para os fotoperíodos de 10L:14E, 12L:12E e 14L:10E, respectivamente. Os fotoperíodos também não afetaram a histologia dos órgãos e ultraestrutura dos ovaríolos. Cada ovaríolo apresentou morfologia tubular e três regiões bem características. O filamento terminal é constituído por tecido conjuntivo. No germário as ovogônias, estão em intensa atividade mitótica e associadas às células foliculares. Cada compartimento do vitelário é revestido internamente por células foliculares, contendo vários ovócitos em diferentes estágios de desenvolvimentos. O oviduto lateral é revestido por tecido epitelial simples cúbico com numerosas dobras, tecido conjuntivo e tecido muscular. No oviduto comum o epitélio apresenta íntima e uma camada muscular bem desenvolvida. A espermateca é revestida por tecido epitelial pseudo-estratificado colunar comuma espessa íntima e duas camadas de tecido muscular, uma longitudinal e outra circular, e entre elas tecido conjuntivo. Ultraestruturalmente os ovaríolos apresentaram-se revestidos por uma bainha espessa constituída por um material homogêneo e filamentoso. No filamento terminal observaram-se células com núcleos volumosos e escasso citoplasma, além de uma matriz extracelular abundante com várias estruturas filamentosas. No germário as ovogônias são maiores com núcleos volumosos, escassos citoplasma e membrana celular com interdigitações. As células foliculares são menores e apresentando projeções citoplasmáticas. No vitelário as célulasfoliculares sofrem modificações na sua morfologia, variando de cúbica a achatada.