The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.

Eland Tragelaphus oryx are the largest and slowest African antelope, falling within the preferred weight range of the prey of lions Panthera leo. Little is known, however, about the antipredatory strategies employed by eland. Rapid population declines in several small reserves following the reintroduction of lions suggest that the antipredatory strategies of eland may be compromised in spatially limited areas. This emphasises the need for research aimed at investigating how eland respond to lions, particularly in the spatial context, given that lions are increasingly being reintroduced into small reserves in South Africa. This study aimed to investigate lion-eland interactions at multiple scales and determine where on the landscape eland were vulnerable to predation. Adult female eland (n = 3 per site) in breeding herds were collared with GPS satellite collars in two study sites; the Nyathi section of Addo Elephant National Park (Nyathi) and Mountain Zebra National Park (MZNP) in the Eastern Cape, South Africa. A reintroduced population of lions, comprising two males and one female, was present in each study site, with individuals fitted with GPS satellite collars. At a broad spatiotemporal scale, eland did not avoid lions and there was considerable overlap between eland and lion home ranges in both study sites. At a finer spatiotemporal scale however, eland and lion space use was asynchronous in time, except in the case of the female lion in Nyathi where there was considerable overlap at the finest temporal scale investigated (i.e. monthly). Herd-associated eland in Nyathi were killed most frequently in areas associated with high long-term use by the female lion, showing that failure to avoid the female lion at a fine scale increased predation risk for eland. Secondly, eland in Nyathi were killed most frequently in habitat types of intermediate structural density (i.e. mixed habitats), which limited the viewshed of eland but presumably offered increased forage. This habitat type was selected for by eland, despite it being associated with a higher level of predation risk. This suggested that eland in Nyathi traded off safety for forage. In MZNP, predation of herd-associated eland was low which reflected the limited spatial overlap between eland and lion at a fine scale in this reserve. In Nyathi, but not in MZNP, eland responded to lions within 1.5 km by increasing their movement rate, with this response particularly strong at night. The findings of this study show that eland responses to lions are scale-dependent and site-specific. Furthermore, eland responses to lions were shown to be lion gender-specific. This study has increased our understanding of the antipredatory behaviours of eland and demonstrated the importance of investigating prey responses to predation risk at multiple scales.

Humans are modifying the global landscape at an unprecedented scale and pace. As a result, species are declining and going extinct at an alarming rate. Here, I investigate two main aspects of species’ declines: what factors are contributing to their declines and how effective our conservation efforts have been. I assessed one of the main mechanisms for protecting species by looking at the Endangered Species Act (ESA) in the United States. I examined three separate indicators of species declines for different groups of species: range contractions in Canadian imperilled species, declines in abundance in global amphibian populations and increases in temporal variability in abundance in North American breeding birds. I found that change in recovery status of ESA listed species was only very weakly related to the number of years listed, number of years with a recovery plan, and funding. These tools combined explained very little of the variation in recovery status among species. Either these tools are not very effective in promoting species’ recovery, or species recovery data are so poor that it is impossible to tell whether the tools are effective or not. I examined patterns of species’ declines in three different groups in relation to a number of anthropogenic variables. I found high losses of Canadian imperiled bird, mammal, amphibian and reptile species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. This is consistent with the hypothesis that agricultural pesticide use, or something strongly collinear with it (perhaps intensive agriculture more generally), has contributed significantly to the decline of imperiled species in Canada. Global increases in UV radiation do not appear to be a major cause of amphibian population declines. At individual sites, temporal changes in amphibian abundance are not predictably related to changes in UV intensity. Variability in species’ abundance of North American breeding birds, after accounting for mean abundance, is not systematically higher in areas of high human-dominated land cover or climate change. Rather, it appears that areas with a high proportion of human-dominated cover come to have a higher proportion of highly abundant, and thus more variable, species.

Earlier studies have found that endangered species recovery is only weakly associated with the tools enabled by the U.S. Endangered Species Act (ESA). With habitat loss often cited as a leading cause of species declines, we tested whether the recovery of ESA-listed species is instead associated with the protection of critical habitat (CH) by protected areas. We tested the relationship for 299 species using recovery indices derived from the biennial status reports to Congress (1990-2010), as well as NatureServe and IUCN population status data. We found no overall relationship between recovery and the extent to which CH is protected. However, restricting the analysis to recovering species, listed species with larger areas of protected (R2 = 0.158) or strictly protected (R2 = 0.194) CH fared better than species with less protected or strictly protected CH areas. Declining species (199 of 273 species studied) fared no better with more protected habitat. We conclude that the abatement of habitat loss alone does not necessarily facilitate recoveries for the majority of ESA-listed species. We also note that the weak relationships we observed in this study may be reflective of poor recovery status estimates.

The last 50 years was characterized by a dramatic decrease in free-roaming cheetah populations and consequently the cheetah now appears on the IUCN Red List for Threatened Species. In order to save cheetahs from extinction, a number of projects were launched to breed cheetahs in captivity. Captive cheetahs, however, receive fundamentally different diets than their free-roaming counterparts, which necessitates feed supplementation to fulfill their unique dietary needs. The Hoedspruit Endangered Species Centre (HESC) is one such project aiming to breed captive cheetahs. At the HESC, a number of juvenile cubs were diagnosed with a form of relaxed carpal joints, namely metacarpal deformity of the front legs. Literature suggests that the condition is due to a magnesium deficiency, which is a consequence of an unbalanced diet. Supplementing magnesium to the diet of cheetahs can, however, affect the urinary system negatively: such as the formation of urolithiasis. V The aim of this study was to determine whether dietary magnesium supplementation in the diets of captive cheetahs will remedy metacarpal deformity and also to investigate the influence of magnesium supplementation on the formation of urolithiasis. The study was divided into two phases. Phase 1 was conducted to determine the influence of dietary magnesium supplementation on metacarpal deformity, identified in juvenile cheetahs at the HESC. To determine the degree of deformity, a leg deformity scoring system was developed. On a scale from 1-3, the cheetahs were scored twice to determine the Flexed Deformity Score (FDS) and Rotational Deformity Score (RDS) values before and after dietary magnesium supplementation. Phase 2 was conducted to determine the influence of magnesium supplementation on different physiological parameters that have an influence on the formation of urolithiasis. Phase 2 was divided into three periods. During each period, the cheetahs received a different diet. During period C, the experimental period, the cheetahs were divided into two groups. One group received a meat-only diet, whereas the other group received a meat-Mg diet. At the end of each of the three periods, blood- and urine samples were collected and analyzed to determine the concentration of minerals in the cheetah’s blood plasma and urine. Based on the FDS and RDS scores, a 25.5% response rate to dietary magnesium supplementation on rotational deformities was found, whereas a 60.8% response rate on flexural deformation was found. It is thus concluded that dietary supplementation of magnesium in juvenile cheetahs that experience metacarpal deformities, will remedy the deformity. By analyzing the changes of different blood- and urine parameters in the cheetahs it was observed that dietary magnesium supplementation do influence the formation of urolithiasis. The physiological state of the cheetahs can influence these parameters. The results obtained from the study can be utilized by nutritionists, veterinarians and institutions to enhance the health of captive cheetahs. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Understanding the health of rare and at-risk plant species is crucial for the conservation of biodiversity. Rare and at-risk species are often specialists with very specific requirements for growth and reproductive success. Some parameters associated with growth and reproductive success of rare aquatic species may include biotic and abiotic factors such as herbivory, competition, water depth, pH, and other factors associated with habitat quality. In this thesis, the population health of the rare and at-risk aquatic species Plantago cordata in Southern Illinois streams is assessed in relation to stream quality of sites containing Plantago cordata and sites without Plantago cordata.The objectives of this study were to (1) Determine if there is a relationship between population size structure and biotic habitat factors among populations and sites, and (2) Determine if there is a relationship between population size structure and abiotic habitat factors among populations and sites. Hypotheses were constructed using the hierarchy-of hypotheses method and most narrow alternative hypotheses are as follows: (1) There will be significant relationships between biotic and abiotic factors and Plantago cordata growth and reproductive success. (2) Levels of herbivory will have significant relationships with growth and reproductive success of Plantago cordata. (3) The abundance of co-occurring species individually and considered in functional groups (graminoid, herb, woody) will have significant relationships with growth and reproductive success of Plantago cordata. (4) Stream depth will have a unimodal relationship with growth and reproductive success of Plantago cordata, with maximum performance at an intermediate stream depth. (5) Stream pH will have a unimodal relationship with growth and reproductive success of Plantago cordata. (6) Stream quality (as outlined by the QHEI assessment) will have significant relationships with growth and reproductive success of Plantago cordata. General trends in herbivory suggest that Plantago cordata could be at greatest risk of herbivory during warmest average temperatures of the study season. There is evidence to suggest that flowering individuals could have a greater threat of herbivory than other growth stages based on Kendal correlation results. A Wilcox test determined that there were no statistical differences in species richness for plots with versus without Plantago cordata. There were relatively low values for percent cover of co-occurring species when considered in functional groups and there was overall relatively low species richness across all communities. Despite this, non-metric multidimensional scaling (NMDS) of community data provided evidence to suggest that there were statistical differences in the species composition of co-occurring individual riparian species among P. cordata populations. A significant negative correlation for water depth and flowering individuals and a significant positive correlation with water depth and pH occurred. A significant positive correlation for stream pH with the numbers of seedlings and dehiscing individuals was also found. One-way analyses of variance (ANOVAs) showed that some populations containing Plantago cordata were found to have stream pH values statistically different from nearby IEPA control streams without Plantago cordata. One population of Plantago cordata was found to be significantly different than two other populations in regards to stream pH using a linear mixed model. A principal components analysis (PCA) of stream Qualitative Habitat Evaluation Index (QHEI) assessments demonstrated distinct clustering of Plantago cordata streams and control IEPA streams without Plantago cordata. These findings provide partial evidence to suggest that growth and reproductive success of Plantago cordata could potentially be impacted by the abiotic and biotic parameters explored in this thesis.

Ways of understanding, living, and communicating with non-human species, and more specifically endangered species, have been thought of dualistically and hierarchically in Western cultures. This type of thinking is harmful when examining environmental issues that involve more than just humans, which is arguably all environmental issues. By enforcing a nature/culture dichotomy, humans are seen as separate from nature and therefore they can ethically excuse themselves from dealing with environmental issues that happen "out there" in nature. This thesis explores two manifestations of this nature/culture separation as it continues to threaten wild orca populations in Puget Sound. The first is because of an anthropocentric culture and the second is because of the capitalist socio-economic system. The anthropocentric part of this type of thinking raises humans up on a pedestal, above all non-human species. It gives humans the excuse to only care about issues that affect them directly. The capitalistic part of this type of thinking enforces human's exploitation and commodification of nature. I argue that anthropocentrism and capitalism together create a human/nature relationship that harms nature and benefits humans. This relationship is illustrated by a small population of orcas, called the Southern Resident Killer Whales (SRKW), off the coast of Washington State that are endangered because of human interference. Lack of prey, toxic water pollution, and excessive noise from boats caused them to become endangered, and these issues are produced by Western society's anthropocentric attitudes and capitalistic systems. The SRKW's will go extinct if the environmental destruction of Puget Sound doesn't end and it will only end if the anthropocentric attitudes and capitalistic systems are dismantled.

Seasonality estimates based on archaeological shellfish remains have been an important component of settlement pattern reconstruction. Investigations of this nature allow researchers to place prehistoric people on the landscape at points in space at different times of the year. Many of the previous seasonality studies, however, have focused on marine species from coastal sites, with little attention given to freshwater locales, especially ones in the Mississippi Delta. To address that disparity, this study examines freshwater mussel “season of capture” via analysis of stable oxygen isotope ratios in specimens recovered from two Late Woodland sites located along the Yazoo River, Mississippi. As freshwater mussel shells are composed of aragonite, a metastable form of calcium carbonate (CaCO3), they can suffer greatly from the impact of meteoric diagenesis. Because of this, samples must be evaluated for diagenesis prior to any geochemical analysis taking place. Archaeological shell samples were examined via thin-section petrography and scanning electron microscopy (SEM). Visual analysis indicated pristine aragonite microstructure and crystallography in all archaeological shell samples, and confirmed their suitability for isotope analysis. Vetted shells were then micromilled across accretionary growth bands, and analyzed for their oxygen isotope signatures. Isotope profiles were then interpreted for their individual “season of capture”, and oscillation patterns for 22 shell specimens indicated mussels were being collected in all four seasons. These data support the view that at least some portion of the human population at both sites engaged in shellfishing activities year-round, indicating sedentary populations at both locales. The shell assemblages were also investigated for the purpose of informing modern conservation efforts (i.e., “applied zooarchaeology”). Nearly 24,000 valves were analyzed taxonomically, yielding the presence of 37 species, of which 24 represented new river records for the Yazoo River. These data provide a valuable historical perspective, cataloging communities as they existed prior to extensive modern impacts, thus representing an ecological baseline to be compared with modern populations. Though modern data are extremely limited for the river, the study revealed it once supported a diverse mussel community containing numerous species currently considered rare, endangered, or extinct in Mississippi.

No description available.

Astragalus ampullarioides and A. holmgreniorum are two rare endemics of southwestern Utah. Over two consecutive field seasons (2009-2010) we examined pre-emergent reproductive success, based on F/F and S/O ratios, from populations of both Astragalus ampullarioides and A. holmgreniorum, estimated the density of the soil seed bank of A. holmgreniorum as a measure of potential post-emergent reproductive success, and estimated seed persistence within the soil seed bank. Fruit/flower (F/F) ratios and seed/ovule (S/O) ratios varied significantly between populations and among years in both species, and showed low reproductive output in both taxa. In Astragalus ampullarioides F/F and S/O were 0.06±0.01 and 0.16±0.02, respectively (2009), and 0.14±0.01 and 0.41±0.02, respectively (2010). For Astragalus holmgreniorum F/F and S/O ratios were 0.11±0.01 and 0.38±0.02, respectively (2009), and 0.23±0.01 and 0.66±0.02, respectively (2010). Although Astragalus holmgreniorum exhibited a low soil seed bank density (4.3 seeds m-2), seed persistence data showed low a low percentage of seeds germinated during the first year in the soil seed bank. Seeds remaining in the seed bank maintained high percent viability. Soil seed persistence of Astragalus ampullarioides differed from A. holmgreniorum in that a high percentage of seeds germinated during the first year in the soil seed bank. A high percentage of viability in ungerminated seeds was also maintained in A. ampullarioides. Although these species differ in life histories and dependence on soil seed banks, an understanding of the strategies unique to each species will prove useful in management plans.