Aluminum spring-band dendrometers were used to measure within-season tree growth at three sites (dry, mesic, and wet) in the Big Thicket National Preserve, Texas to determine what affects within-season tree growth and if patterns of growth vary among species, sites, and years. Growth patterns were found to differ among sites when the variation among species was removed, and among years and species. Significant interactions implied that trees were responding differentially to weather variation. Temperature, rain, soil moisture, and deficit were found to affect the within-season growth of trees. However, site patterns seemed to mediate the effects of weather, and intrinsic seasonal growth patterns defined how different species responded to weather variation. My results suggest that climate change will differentially affect tree growth, depending on species and how within-season weather patterns change.

Invasive species can cause significant changes to their introduced environments. A set of experiments was conducted to determine whether Sapium sebiferum exhibits allelopathic effects on neighboring plants in its introduced range. Bioassays were performed on Sapium, Liquidambar styraciflua, Schizachyrium scoparium, Andropogon ischaemum, and Lolium perenne seeds using extracts from Sapium, Acer saccharinum, Platanus occidentalis and Liquidambar leaves. Germination and early growth comparisons were made using: (1) solutions treated with activated carbon to remove allelochemicals or left untreated, (2) solutions in a dilution series, and (3) solution mixtures prepared from rinsed leaves or soaked leaves using activated carbon to negate potential allelopathic effects of all but one leaf species in each mixture. In almost every analysis there were few significant predictors. The effects of Sapium extracts on germination or growth never differed from those of the three native tree species' extracts. Allelopathy does not appear to contribute to Sapium's invasive success.

I investigated the role of shade tolerance in the dynamics of three forests of Big Thicket National Preserve, southeast Texas. In a mature mesic forest, shade-intolerant species had higher high-light growth and lower low-light growth than tolerant species. Results suggested that there was a tradeoff between high-light growth and low-light growth across species. Moreover, low-light survival and high-light growth were negatively correlated across species. In contrast to northern hardwood forests where survival in low light may be achieved at the expense of growth, my results suggested that shade-tolerant species in this southern mixed forest can grow faster as well as survive better than shade-intolerant species in low light. I conclude that both juvenile growth and survival are important components of shade tolerance and their relationships may be system-specific. In a floodplain forest, growth responses to light were consistent with the expectation that shade-intolerant species grow faster than shade-tolerant species in high light and vice versa. But mortality risks of some shade-tolerant species were unexpectedly high. The increased flooding during one of the study time periods may be responsible for the high mortality risks of shade-tolerant species. The results further supported that the success of shade-tolerant species in this forest may be limited by flooding as previous studies suggested. Compared with the mesic site, common species showed little intraspecific differences in shade tolerance. In a sandy upland pine-oak forest, low-light growth responses of saplings corresponded to shade tolerance expectation. However, shade-intolerant species did not show faster growth than shade-tolerant species in high light possibly because these species are drought-tolerant. The correspondence between increasing stem density and increasing death rates of shade-intolerant xeric dominants suggested that recent increases in canopy shading may be responsible for high death rates of these species. Cross-site comparison showed that shade-tolerant species had better performance at the dry site than at the mesic site. Consistent with the facilitative effect found at dry sites, these species may benefit from the less competition from surrounding vegetation.

Ecology is the scientific study of processes that determine the distribution and abundance of organisms in space and time. Animal movement plays a crucial role in determining the fates of individuals, populations, communities, and ecosystems. Hence, understanding how and why animals change their spatial location through time is fundamental to ecological research. Animal movement patterns reflect behavioral, physiological and physical interactions between individuals and their environment. Coupling movement and environmental data may thus provide a rich source of information regarding many aspects of animal ecology. In my PhD thesis, I develop and demonstrate different approaches to understanding and predicting animal movement patterns in relation to their environment. In the first chapter, I merge two fundamental ecological models, the functional response and random walk, to formally derive diffusion rates of consumers as function of their handling time and the abundance, distribution and mobility of their resources. This mechanistic null model provides a simple behavior-free explanation to commonly observed negative associations between movement rates and resource abundance, often attributed to area-restricted search behavior. In the second chapter, I use positional data of woodland caribou in Ontario to calculate random walk-based movement expectations for each individual during each month. I then statistically link these expectations to ecologically significant environmental conditions. I show that landscape correlates of forage abundance and habitat permeability explain much of the observed variation in caribou movement characteristics and that residual variability may be attributed to spatial population structure. In the third chapter, I develop a novel state-space approach, enabling simultaneous consideration of resource preference, cognitive capacities and movement limitations, within a simulation model of animal movement across heterogeneous landscapes. The model is designed to enable direct parameterization based on empirical movement and landscape data. This approach allows one to both theoretically explore the consequences of different cognitive abilities and to predict animal space-use patterns across novel or altered landscapes. Overall, my thesis contributes to the rapidly developing field of movement ecology by formulating mechanistically defendable linkages between animal movement and landscape characteristics.

No description available.

The purpose of this qualitative study was to explore how female collegiate volleyball athletes use dress and appearance practices to create, maintain, and negotiate their sport identity and gender identity, in-sport and everyday, from the time they played collegiate volleyball to present day. The study was guided by grounded theory and phenomenology. Semi-structured, in-depth, active qualitative interviews with 12 women, who represented American, Brazilian, Canadian, and Romanian viewpoints, were analyzed using open coding and thematic analysis procedures. Analysis revealed three key themes related to female collegiate volleyball athletes use of dress and appearance practices as a means to shape and influence their sport and gender identities: (a) conceptualizing the female collegiate volleyball culture as understood by dress and appearance, (b) female collegiate volleyball athlete subject formation, and (c) performing female collegiate volleyball athlete identities. Findings revealed that they used dress and appearance practices to understand their sport identity and gender identity when they played volleyball in college and that they currently use dress and appearance practices in their everyday lives as a way to understand their subject positions. Female collegiate volleyball athletes conceptualized their ways of understanding social and cultural expectations by using their dress and appearance practices and bodies as mediums for interpretation.

Studying the winter ecology of freshwater fishes has been a focus of much past and present research. Because of obvious constraints with studying fish in situ during the winter, few studies have made links between laboratory findings and observations made in the natural environment. Recently, new developments in biotelemetry have provided a way of assessing the winter ecology of fish in a natural setting. At present, however, there are few, if any, studies that attempt to make direct links between field and laboratory results. This research focuses on the reaction of largemouth bass (Micropterus salmoides) to winter conditions using both biotelemetry and laboratory components. In the first part of the study, biotelemetry-derived swimming activity is assessed across a range of temperatures (4.0-25°C). As well, swim tunnel-derived Ucrit swimming speeds and burst swimming ability across similar temperatures were evaluated. In both cases, swimming activity and speeds decreased as temperatures decreased. In biotelemetry-derived measurements, swimming activities increase late in winter, possibly suggesting acclimatization. In the second part of the study the effect of hypoxia on winter habitat selection was investigated. Biotelemetry-obtained locations of largemouth bass were compared to the distribution of dissolved oxygen throughout the lake at numerous times throughout the winter. In addition, experiments were conducted in a laboratory setting on winter juvenile fish to determine the behavioural and physiological impacts of hypoxia. The results of these experiments revealed a behavioural response in the lab and habitat avoidance in the field at an environmental oxygen level of approximately 2 mg/L of dissolved oxygen. The combination of biotelemetry with laboratory data has demonstrated that more informative results about the winter ecology of freshwater fishes can be derived. In the future, usefulness of this combined approach in assessing the impacts of climate change on fish populations will be invaluable. / Thesis (Master, Biology) -- Queen's University, 2007-08-28 13:59:30.215

Migratory birds spend most of the year on the over-wintering grounds or traveling between breeding and wintering areas, but research has focused on the relatively short breeding period. As a consequence, we have only a rudimentary understanding of how life histories of long-distance migrants are shaped by events and selective pressures interacting throughout the annual cycle. In this thesis, I examine the association between plumage traits and performance, both during the over-wintering and breeding phases of the annual cycle and how events during one season carry-over to influence behavioural and evolutionary processes in subsequent seasons in a migratory warbler, the American redstart (Setophaga ruticilla). First, I demonstrate that tail feather brightness is correlated with winter habitat quality in Jamaica, suggesting that plumage may act as a status signal during the non-breeding season. Stable-carbon isotopes analyzed from claws of redstarts arriving on the breeding grounds confirm the association between ornamentation and winter territory quality. Second, I demonstrate that redstarts arriving to breed in southern Ontario from high-quality winter habitats arrive earlier, resulting in a lower probability of paternity loss, a higher probability of achieving polygyny, and higher genetic fledging success. Third, I demonstrate that tail feather brightness, associated with winter territory quality, predicts the likelihood of polygyny during the breeding season, indicating that tail brightness is associated with performance during two phases of the annual cycle. Paternity is predicted by both tail and flank colouration. Finally, I demonstrate that reported trade-offs between reproductive effort and plumage ornamentation as manifested by moult-migration in redstarts is likely an artifact of high variation in local stable-hydrogen isotope signatures (δD) and occasional feather loss and re-growth during the over-wintering period. Thus, moult-migration does not appear to be an important carry-over effect in redstarts. This work demonstrates that plumage may be under selection during both stationary phases of the annual cycle. Furthermore, it suggests that carry-over effects from the non-breeding season can influence evolutionary processes such as sexual selection and highlights the importance of considering selective pressures and events occurring throughout the annual cycle in studying the behaviour and ecology of migratory animals. / Thesis (Ph.D, Biology) -- Queen's University, 2008-09-21 17:31:31.419

Walleye (Sander vitreus) is an important species to the recreational fishery throughout Ontario. Fish community interactions between walleye and other species are rarely considered when establishing management targets which may lead to the creation of conflicting management objectives. Other studies that have focused on competitive interactions between species have typically focused on interactions between two species in isolation of the remaining species within the fish community and considered only a small subset of lakes. My study examined how the presence/absence of multiple species within the fish community affects the abundance of walleye across a broad spectrum of habitat conditions and fisheries. A Schaefer model was modified by distinguishing carrying capacity into a habitat and fish community component to account for between lake differences in suitable habitat prior to testing for interactions. Walleye catch-per-unit effort (CUEW, kg/net) was assessed in 140 Ontario lakes using the Fall Walleye Index Netting Protocol. An all subsets approach was used to estimate parameters in a multiple regression. Fish community and fishing pressure were significant predictors in explaining walleye abundance (adjusted R2=0.45, p<0.001). The presence of bluegill (Lepomis macrochirus) and smallmouth bass (Micropterus dolomeiu) were significant negative predictors in the top model (αbluegill = -1.54, partial r2=0.1; αsmallmouth = -0.28, partial r2=0.03). In many studies, smallmouth bass have also been found to have a significant diet overlap with walleye. These interactions present challenges when establishing management objectives for mixed fisheries. / Thesis (Master, Biology) -- Queen's University, 2012-09-21 18:23:34.119

No description available.