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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Population trends, conservation and the trade in amphibians in Asia

White, Steve January 2005 (has links)
published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
122

Ecohydrological Conditions Associated With The Distribution And Phenology Of The Pima Pineapple Cactus

Kidder, Amí Lynne January 2015 (has links)
Climate changes in temperature and precipitation are already occurring and are projected to further exhibit increasing temperature and precipitation extremes and increasing variation. Such increased temperature variation and decreased precipitation are likely to have a profound impact on vegetation communities, particularly in regions that are dominated by extreme temperatures and strongly seasonal precipitation events. Both temperature and precipitation are tightly linked to vegetation growth and distribution, and in regions such as the U.S. desert southwest, there are a number of rare and endangered species that have a particularly tight knit relationship with their environment. Here, I examine the relationship between these ecohydrological drivers and a specific, little- researched cactus: the Pima Pineapple Cactus (Coryphantha scheeri var. robustispina). C. scheeri is a small, hemispherical cactus that resides in the Santa Cruz and Altar Valleys of Southern Arizona, and very little is known about the conditions that promote C. scheeri distribution and growth. To provide information that may aide in managing this species, I investigate aspects of the distribution and the phenology of this species. With respect to distribution, I hypothesize that (H1) C. scheeri locations are associated with spatial physical and climatic data within its geographic limits. A framework describing the climatic associations of C. scheeri would enable species managers to take advantage of suitable habitat when opportunities arise. With respect to phenology, within established C. scheeri habitat we lack a clear understanding of the impact ecohydrological factors can have on reproduction and size. Therefore, I also hypothesize (H2) that C. scheeri flowering phenology is triggered by available moisture, which may be in the form of precipitation, humidity, or soil moisture. My results indicate that through the use of the classification tree, C. scheeri habitat is strongly associated with climatic and physical variables at a state-wide scale; these associations indicate large losses of suitable habitat under future projected climate scenarios. Additionally, I find that C. scheeri flowering phenology appears to be associated with precipitation and the resulting increase of soil moisture; the data are also suggestive that bud formation might be associated with water-year growing degree day. Because the results indicate a tight coupling with climatic variables, with most suitable habitat within the current range in Arizona projected to be lost under future climate, I suggest managers may be inclined to increase monitoring C. scheeri in an ecohydrological context relative to the variables identified here and to consider conditions and locations where supplemental watering or microclimate amelioration could be beneficial for the species.
123

Competition for Conifer Cones as a Potential Mechanism of Endangerment for the Mount Graham Red Squirrel

Minor, Rebecca January 2010 (has links)
Non-native species are a major cause of endangerment for native species, but the mechanisms are often unclear. As species invasions continue to rise, it is important to understand how to mitigate this threat. Our field experiment quantified the impact of introduced Abert's squirrels (Sciurus aberti) on rates of food removal within the range of the critically endangered Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis). In the presence of Abert's squirrels, the time until 50% of cones were removed was 5.55 days faster than when Abert's squirrels were excluded (95% confidence interval 2.25 to 11.63 days). The impact on food availability as a result of cone removal by Abert's squirrels suggests the potential of food competition as a mechanism of endangerment for the Mount Graham red squirrel. Eradication of established non-native populations is rare. Management targeted at specific mechanisms by which non-natives cause endangerment is an essential tool for conservation.
124

Binational collaboration in recovery of endangered species: the Mexican wolf as a case study

Bernal Stoopen, Jose Francisco 30 September 2004 (has links)
The goal of this inductive study was to identify factors that facilitate and inhibit binational collaboration in the recovery of endangered species in the northern Mexico borderlands, focusing on the Mexican wolf (Canis lupus baileyi). A conceptual model was developed using qualitative techniques, providing the basis for design of a mail survey. The target population included participants with experience in recovery efforts for over a dozen species at risk in the region. Long interviews were recorded with 44 participants from Mexico and the United States. Thematic hierarchical analysis was used to develop a conceptual model of how interviewees talked about factors influencing binational collaboration. Issues were classified in five thematic clusters: project, organization, people, resources, culture/history. The survey was used to conduct a needs assessment, measuring respondents' attitudes about the relative priority of issues identified in the conceptual model. High priority needs were identified from each thematic cluster: (a) equitable participation in project design and implementation, (b) continuity of personnel, (c) coordination of federal, state and local efforts, (d) increased funding, managed with accountability, and (e) exchange visits to facilitate understanding of diverse perspectives. Responses to almost half the survey items indicated accord among the sample of respondents, providing a basis for shared common ground. The nature of discord was within the range of "manageable", with no clear polarization of attitudes measured. This exploratory data analysis suggested that the structure of the conceptual model developed from the Mexican wolf case study was generally a valid basis for future deductive analysis and reflection by practitioners. For 82% of 22 statements of need, priorities of participants in the Mexican wolf recovery efforts did not differ significantly from other respondents. Nationality (of respondents) significantly affected priority rankings for only 18% of the need statements. Significant effects of five demographic variables indicated that interactive effects should be examined in future multivariate analyses to determine how respondents' attitudes on issues related to priority rankings. Recommendations were provided for a more efficient and effective approach to collaborative problem-solving, engaging reflective practitioners from the private and public sectors in principled negotiation processes to better understand diverse perspectives.
125

Federal endangered species legislation in Canada : explaining the lack of a policy outcome

Amos, William Ambrose 11 1900 (has links)
This thesis attempts to uncover the reasons why Canada, unlike the United States and Australia, does not have stand alone federal endangered species legislation. In particular, I will focus upon the history of Bill C-65, the proposed federal endangered species statute which died on the Order Table in 1997. Using the "policy regime" framework developed by George Hoberg, I examine the ideas, actors, and institutions that have combined within a given set of background conditions to produce this distinctive lack of a policy outcome, assessing the relative causal importance of each variable in terms Bill C-65's failure. Using Peter Haas' epistemic community approach, the causal knowledge of conservation scientists' regarding habitat loss is found not to have influenced the policy substance of Bill C-65. However, it is argued that scientists did play an important role in the legislative failure insofar as they joined forces with environmentalists to discredit the weak scope and substance of the bill. These pro-environment actors, however, were matched throughout the interest group competition by the parallel forces of industry and private landowner groups, who criticized Bill C-65 as a litigious, punitive and "American" style of legislation. The provinces, for their part, sided with the landowners and industry groups, arguing that the federal government had overstepped its wildlife management jurisdiction. Given a context of low public concern for environmental issues, and the institutional trend towards regulatory decentralization, the federal government had very few incentives to introduce a strong bill. However, the provinces, landowners, and industry groups, all felt it was too strong, while environmentalists and scientists felt just the opposite. Bill C-65's failure, therefore, was the result of the federal government's inability to satisfy anyone on this issue. Determining who "won" this first endangered species battle, however, is quite difficult without knowing whether Cabinet felt the bill was too strong or too weak, and without knowing what the next legislative proposal will entail. In conclusion, it is found that all three regime components of ideas, actors, and institutions were equally important factors in bringing about the failure of Bill C-65, and the current policy delay that continues to this day.
126

Microsatellite variability in four contemporary rhinoceros species : implications for conservation

Scott, Candace A. 08 July 2008 (has links)
Rhinoceroses are arguably the most endangered of all large mammal taxa. In order for ongoing conservation of this species to be successful, it is crucial to accurately characterize the remaining genetic diversity for all rhinoceros species. To do this, I optimized a standard suite of 24 taxon-specific rhinoceros microsatellite loci. These loci have the power to provide the most comprehensive estimate of comparative microsatellite genetic diversity within and among the four extant African and Asian rhinoceros genera. These loci were further used to evaluate the comparative influences of rhinoceros species versus microsatellite taxonomic origin as predictors of rhino microsatellite diversity, and finally to examine the evolutionary relationships between extant rhino taxa. The African black michaeli rhino subspecies had the highest level of microsatellite genetic variability of all available rhinos, while southern white and Indian rhinos were the least variable rhinos. These findings also suggested that species and taxonomic origin of microsatellite loci were both significant predictors of microsatellite heterozygosity in rhinoceroses. A weak association between the Sumatran and black rhinos was found with a DLR neighbour-joining tree. The standard loci were able to assign unique genotypes to all available rhinos as well as differentiate between all rhino species by correctly assigning individual rhinos back to their respective populations. / Thesis (Master, Biology) -- Queen's University, 2008-07-02 23:01:32.553
127

Investigating downstream passage of lake sturgeon, Acipenser fulvescens, through a Winnipeg River generating station

McDougall, Craig 13 January 2012 (has links)
Lake sturgeon, recently recommended to be listed as an endangered species under the Species at Risk Act, inhabit the various impoundments of the Winnipeg River system. Downstream passage through hydroelectric generating stations represents one of the major data gaps in our understanding of how hydroelectric development may be impacting lake sturgeon populations. Acoustic telemetry was used to investigate coarse-scale movements of juveniles, sub-adult and adults throughout the Slave Falls Reservoir, a 10 km long Winnipeg River impoundment, to assess patterns of downstream passage susceptibility and investigate fine-scale movements in the vicinity of the Slave Falls Generating Station. Movements of juveniles and sub-adults were generally restricted to areas of interconnected deep-water habitat, with movements through the shallow river narrows that sub-divide the Slave Falls Reservoir being rare. Adults did move through these narrows, albeit infrequently. Juveniles and sub-adults tagged in the lowermost section of the reservoir, as well as several adults tagged throughout the reservoir, were found to periodically utilize habitat immediately upstream of Slave Falls, where they would be susceptible to entrainment. Mean entrainment rates were estimated at 3.1% per year for adults tagged throughout the reservoir, and 17.9% per year for sub-adults tagged in the lowermost section of the reservoir. Fine-scale movement tracking revealed that three of eleven observed downstream passage events occurred via bottom-draw regulating gates, while another four events were also reasoned to have occurred via this route. The routes of the remaining four could not be determined. Eight of the eleven downstream passage events observed in this study were survived. While the survival of the remaining three fish could not be confirmed, it is highly likely that they also survived. Length-at-age analysis, supported by genetic methods, revealed that 23 of 151 (15.2%) of the lake sturgeon between 525 and 750 mm (fork length) captured in the 6 km stretch of river downstream of Slave Falls were fast-growing outliers, reasoned to have passed downstream through the Slave Falls Generating Station.
128

Pollination and comparative reproductive success of lady's slipper orchids Cypripedium candidum, C. parviflorum, and their hybrids in southern Manitoba

Pearn, Melissa 23 January 2013 (has links)
I investigated how orchid biology, floral morphology, and diversity of surrounding floral and pollinator communities affected reproductive success and hybridization of Cypripedium candidum and C. parviflorum. Floral dimensions, including pollinator exit routes were smallest in C. candidum, largest in C. parviflorum, with hybrids intermediate and overlapping with both. This pattern was mirrored in the number of insect visitors, fruit set, and seed set. Exit route size seemed to restrict potential pollinators to a subset of visiting insects, which is consistent with reports from other rewardless orchids. Overlap among orchid taxa in morphology, pollinators, flowering phenology, and spatial distribution, may affect the frequency and direction of pollen transfer and hybridization. The composition and abundance of co-flowering rewarding plants seems to be important for maintaining pollinators in orchid populations. Comparisons with orchid fruit set indicated that individual co-flowering species may be facilitators or competitors for pollinator attention, affecting orchid reproductive success.
129

Investigating downstream passage of lake sturgeon, Acipenser fulvescens, through a Winnipeg River generating station

McDougall, Craig 13 January 2012 (has links)
Lake sturgeon, recently recommended to be listed as an endangered species under the Species at Risk Act, inhabit the various impoundments of the Winnipeg River system. Downstream passage through hydroelectric generating stations represents one of the major data gaps in our understanding of how hydroelectric development may be impacting lake sturgeon populations. Acoustic telemetry was used to investigate coarse-scale movements of juveniles, sub-adult and adults throughout the Slave Falls Reservoir, a 10 km long Winnipeg River impoundment, to assess patterns of downstream passage susceptibility and investigate fine-scale movements in the vicinity of the Slave Falls Generating Station. Movements of juveniles and sub-adults were generally restricted to areas of interconnected deep-water habitat, with movements through the shallow river narrows that sub-divide the Slave Falls Reservoir being rare. Adults did move through these narrows, albeit infrequently. Juveniles and sub-adults tagged in the lowermost section of the reservoir, as well as several adults tagged throughout the reservoir, were found to periodically utilize habitat immediately upstream of Slave Falls, where they would be susceptible to entrainment. Mean entrainment rates were estimated at 3.1% per year for adults tagged throughout the reservoir, and 17.9% per year for sub-adults tagged in the lowermost section of the reservoir. Fine-scale movement tracking revealed that three of eleven observed downstream passage events occurred via bottom-draw regulating gates, while another four events were also reasoned to have occurred via this route. The routes of the remaining four could not be determined. Eight of the eleven downstream passage events observed in this study were survived. While the survival of the remaining three fish could not be confirmed, it is highly likely that they also survived. Length-at-age analysis, supported by genetic methods, revealed that 23 of 151 (15.2%) of the lake sturgeon between 525 and 750 mm (fork length) captured in the 6 km stretch of river downstream of Slave Falls were fast-growing outliers, reasoned to have passed downstream through the Slave Falls Generating Station.
130

Pollination and comparative reproductive success of lady's slipper orchids Cypripedium candidum, C. parviflorum, and their hybrids in southern Manitoba

Pearn, Melissa 23 January 2013 (has links)
I investigated how orchid biology, floral morphology, and diversity of surrounding floral and pollinator communities affected reproductive success and hybridization of Cypripedium candidum and C. parviflorum. Floral dimensions, including pollinator exit routes were smallest in C. candidum, largest in C. parviflorum, with hybrids intermediate and overlapping with both. This pattern was mirrored in the number of insect visitors, fruit set, and seed set. Exit route size seemed to restrict potential pollinators to a subset of visiting insects, which is consistent with reports from other rewardless orchids. Overlap among orchid taxa in morphology, pollinators, flowering phenology, and spatial distribution, may affect the frequency and direction of pollen transfer and hybridization. The composition and abundance of co-flowering rewarding plants seems to be important for maintaining pollinators in orchid populations. Comparisons with orchid fruit set indicated that individual co-flowering species may be facilitators or competitors for pollinator attention, affecting orchid reproductive success.

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