Introduced cichlid species are increasingly more common in tropical freshwater systems and expanding in range, often with negative consequences to receiving systems. To better understand, monitor, and manage these populations, improved cichlid sampling protocols are required. The goal of this study was to (1) evaluate diel electrofishing and gill netting sampling catch efficiency, and (2) compare two non-lethal methods for extracting stomach contents from Butterfly Peacock Bass Cichla ocellaris. This study suggests that electrofishing, particularly at night, may be a more appropriate gear for sampling cichlid species in the littoral zone of reservoirs, as gill nets were more time intensive, had more variable catch rates, and exhibited considerable selectivity. Pulsed gastric lavage was more effective than acrylic stomach tubes for extracting stomach contents from Butterfly Peacock Bass and was less injurious, with bruising of the stomach wall the most common injury being observed.

No description available.

Organismal invasions have repeatedly been cited as both a driving force behind global change and beneficiaries of that change. Although many drivers of these invasions have been well studied, few studies have addressed invasions through the perspective of native symbiont communities. In the Mountain Lake region of Virginia, crayfish host diverse assemblages of obligate cleaning symbionts known as branchiobdellida. This cleaning symbiosis has been found to result in significant fitness benefits for native crayfish. Historical survey work showed that invasive crayfish, known to be intolerant of symbionts, were introduced into the region by the 1960s. I carried out an extensive regional survey to determine how this invasion has progressed and what impacts it is having on the native crayfish-branchiobdellida symbiosis. Survey results show that invasive crayfish have successfully spread throughout the region, resulting in the displacement of native crayfish. Additionally, findings suggest that invasion results in significantly reductions in abundance and richness in native symbiont communities. To determine mechanisms contributing to observed impacts on native symbionts, I carried out a study that simulated displacement of native crayfish by invasive crayfish in a controlled setting. This study found that as native crayfish are increasingly displaced by invasive crayfish, both symbiont dispersal and survival are negatively affected. This potential loss of symbiosis caused by invasion may reduce symbionts on native crayfish below abundances necessary for fitness benefits, exacerbating the negative impacts of invasions and presenting a major conservation issue in invaded systems. / M. S. / Introductions of non-native organisms are widely recognized for the negative impacts they have on native biodiversity. Although ongoing study has been directed at understanding many of the factors contributing to invasions, few studies address invasion through the perspective of native symbionts. In the Mountain Lake region of Virginia, crayfish host multiple species of small worms, known as crayfish worms, that provide cleaning services to their crayfish host. These services have been found to provide health benefits to native crayfish. Historical surveys found that invasive crayfish, known to be intolerant of crayfish worms, were introduced into the region by the 1960s. To determine how far invasive crayfish have spread and what impacts they are having on native organisms, I carried out a survey of the region. This survey found that invasive crayfish are now widespread in the region. Additionally, findings suggest that the introduction of invasive crayfish results in reductions in both the number of worms and worm species present. These reductions may be significant enough to prevent health benefits given to native crayfish from occurring. In addition to this survey, I carried out a study under controlled settings to determine what causes negative impacts on native crayfish worms. This study found that as invasive crayfish displace native crayfish, crayfish worms are increasingly killed due to the intolerance of invasive crayfish to the worms. These findings suggest symbiosis should be included in studies of invaded systems if we are to fully understand the introduction and spread of invasive species.

Bird populations are changing at unprecedented rates in response to human-induced changes to the global environment, and these rates of change are expected to accelerate over the coming decades. Changes in the levels of sulphur dioxide (SO2) in the atmosphere through emissions from power stations pose a potential threat to bird populations. However, avian response to SO2 pollution is poorly understood. Exploring the relationship between avian diversity and SO2 exposure levels will help in determining species sensitive to air pollution. This study seeks to understand the interactions between avian diversity and SO2 concentration levels around Matimba power station so as to have more insight on the level of avian vulnerability to air pollution. Matimba is an important site in South Africa as a second coal fired power station, Medupi, is currently being constructed with additional stations also a possibility. This study represents an important baseline assessment of the avian population status before the additional pollution burden is realised from Medupi. Ten min repeated point counts were conducted at three sample sites with varying distances from Matimba and Medupi power stations. These counts were used to calculate bird species density and diversity. Cloud-free Landsat 8 imagery acquired on 7 January, 2014 was used to derive habitat structure and productivity variables. Elevation variables were derived using a DEM (Digital Elevation Model) obtained from NASA Global Data Explorer. The AERMOD dispersion model was used to characterise spatio-temporal variations in ambient SO2 concentrations around Matimba power station. Multiple regression analysis was then used to ascertain which of these variables (SO2, habitat structure, productivity and terrain) contribute most to the observed variation in bird species density and diversity around Matimba and Medupi power stations. SO2 polluted air did not have an influence on bird species density and diversity at the community level. At species level two species (Batis molitor and Streptopelia senegalensis) exhibited some measure of negative response to SO2 air pollution. However, after further investigation using multiple regression analysis it was revealed that habitat structure had more influence on the density of these two species compared with ambient SO2 concentrations. Bird species density and diversity varied significantly among the sample sites but were not related to the distance to the source of the SO2 air pollution. Evidence obtained from this study revealed that continuous monitoring of the interactions between SO2 polluted air and bird populations is recommended for a more comprehensive understanding of avian susceptibility towards SO2 air pollution and this will also facilitate in the selection of sensitive and relevant species for future ecology studies at other coal-fired power stations. Furthermore, it is expected that SO2 concentrations will significantly increase with the commissioning of Medupi power station thus further necessitating the need for continuous monitoring of bird species densities around Matimba and Medupi power stations. / MSc (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2015

Bird populations are changing at unprecedented rates in response to human-induced changes to the global environment, and these rates of change are expected to accelerate over the coming decades. Changes in the levels of sulphur dioxide (SO2) in the atmosphere through emissions from power stations pose a potential threat to bird populations. However, avian response to SO2 pollution is poorly understood. Exploring the relationship between avian diversity and SO2 exposure levels will help in determining species sensitive to air pollution. This study seeks to understand the interactions between avian diversity and SO2 concentration levels around Matimba power station so as to have more insight on the level of avian vulnerability to air pollution. Matimba is an important site in South Africa as a second coal fired power station, Medupi, is currently being constructed with additional stations also a possibility. This study represents an important baseline assessment of the avian population status before the additional pollution burden is realised from Medupi. Ten min repeated point counts were conducted at three sample sites with varying distances from Matimba and Medupi power stations. These counts were used to calculate bird species density and diversity. Cloud-free Landsat 8 imagery acquired on 7 January, 2014 was used to derive habitat structure and productivity variables. Elevation variables were derived using a DEM (Digital Elevation Model) obtained from NASA Global Data Explorer. The AERMOD dispersion model was used to characterise spatio-temporal variations in ambient SO2 concentrations around Matimba power station. Multiple regression analysis was then used to ascertain which of these variables (SO2, habitat structure, productivity and terrain) contribute most to the observed variation in bird species density and diversity around Matimba and Medupi power stations. SO2 polluted air did not have an influence on bird species density and diversity at the community level. At species level two species (Batis molitor and Streptopelia senegalensis) exhibited some measure of negative response to SO2 air pollution. However, after further investigation using multiple regression analysis it was revealed that habitat structure had more influence on the density of these two species compared with ambient SO2 concentrations. Bird species density and diversity varied significantly among the sample sites but were not related to the distance to the source of the SO2 air pollution. Evidence obtained from this study revealed that continuous monitoring of the interactions between SO2 polluted air and bird populations is recommended for a more comprehensive understanding of avian susceptibility towards SO2 air pollution and this will also facilitate in the selection of sensitive and relevant species for future ecology studies at other coal-fired power stations. Furthermore, it is expected that SO2 concentrations will significantly increase with the commissioning of Medupi power station thus further necessitating the need for continuous monitoring of bird species densities around Matimba and Medupi power stations. / MSc (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2015

Understanding broad patterns of biodiversity requires developing a unified and rigorously tested theory that explains how species coexist despite the risk of competitive exclusion. Species interactions are fundamentally shaped by environmental variability. Recent theoretical development has predicted a set of general mechanisms that promote species coexistence under variable environments. Nevertheless, this theoretical framework has received limited empirical tests. Biological invasions offer excellent opportunities to empirically test coexistence mechanisms in communities in which the stability of coexistence is likely affected by introduced species. I took this opportunity to directly test the theory of species coexistence in this dissertation work by investigating how environmental variability affected the invasion of introduced species and their coexistence with native species. My collaborators and I started the investigation of diversity maintenance by first examining the range expansion of introduced species. Studying range shifts can reveal drivers of diversity patterns, which are formed by overlapping ranges of different species. We used a novel spatial analysis to determine the scale-dependent expansion rate of an invasive winter annual species, Brassica tournefortii over North America as well as to infer the drivers of this scale dependency. We found that this species expanded rapidly on scales from 5 to 500 km historically but had ceased its current expansion on the 100-500 km scales due to climatic constraints. This finding left open the question why this species continued its spread on the 5-50 km scales and how it would impact native species within its invaded range. To address these questions, we examined relatively local scale interactions between B. tournefortii and its competitors. We compared key demographic rates of B. tournefortii with other invasive and native winter annuals over a Sonoran Desert landscape to check conditions necessary for their spatial and temporal niche differentiation. We found the presence of two essential requirements for their niche differentiation: species-specific germination responses that could differentiate species by their favored environments and buffered population growth in time and space that could prevent catastrophic population declines when species faced unfavorable conditions. These conditions could provide niche opportunities to promote both the establishment of B. tournefortii and the persistence of native species under its presence. Building upon this finding, we directly quantified one general mechanism of spatial niche differentiation between B. tournefortii and its native competitors. We measured the strength of this mechanism, the spatial storage effect, across a hierarchy of spatial scales (subhabitat -> habitat -> landscape). We found that this mechanism did not promote species coexistence on any of these scales over the study period. These species were not differentiated over their tested spatial niches because weak competition following dry growing conditions failed to intensify intraspecific competition relative to interspecific competition. The strength of this mechanism increased from occasionally producing negative effects on lower scales to consistently being non-negative on the highest scale. This scale-dependent pattern was in line with the expectation that coexistence potential would increase with scales as species interacted over a wider range of environmental heterogeneity. Our findings demonstrated empirically that environmental variability in time and space led to scale-dependent patterns of the coexistence potential between introduced and native species. This work showed that introduced and native species could be differentiated by their environmental responses given spatial and temporal environmental heterogeneity on higher scales. However, for those species to stably coexist on higher scales, competitive effects had to follow environmental responses to separate species by their own density-dependent feedback loops. This work is among the first few empirical tests of a body of theory that holds the promise to generalize the mechanisms of spatial and temporal niche differentiation. Its success and limitation can motivate more studies to adopt the guiding mathematical principles and to use similar yet more innovative approaches to address the grand question of biodiversity maintenance.

Thesis (PhD)--Stellenbosch University, 2012. / Please refer to full text for abstract.

This dissertation examines how eco-knowledge intersects with the changes to EU legal cultures and practices known as eurolegalism. This conjunction has created a mechanism for the extension of EU law in the Member States even in the face of a weakened EU. Through a portfolio of six articles, controversies over the protection of wolves in Sweden are used to illustrate and explicate the changing roles and responsibilities of various actors in protecting species, and the centralization of competence for environmental protection in Europe at the EU level. In doing so, some substantive requirements of the Habitats Directive are also analyzed. The first article maps the movement of competence to determine conservation policy towards the EU level and away from international and Member State actors. The second article examines what the EU requires of its Member States by analyzing the Habitats Directive’s key concept, favourable conservation status. It also makes normative arguments for how contested aspects of this concept should be interpreted to best achieve the Directive’s conservation goals. The third article deepens this analysis by applying these arguments to the Swedish wolf population. The fourth article is a case commentary illustrating the enforcement of the Habitats Directive through public interest litigation to stop the hunting of Swedish wolves. The fifth argues that the greater availability of public interest standing in the US than in the EU has led to the greater implementation of federal law. The sixth argues that greater availability of public interest litigation in Sweden than previously is also leading to the greater enforcement of “federal” EU law. Each of these articles demonstrates or explains factors that lead to the hollowing out of state power in favor of the EU and interest groups. / <p>Cover photo by Guillaume Chapron</p>

To complete an online world Flora by 2020 rapid progress is required towards understanding the taxonomy and distributions of the world's plants. This ambitious target set by the Global Strategy for Plant Conservation is hampered by two facts; first, many species of seed plant remain poorly known and second, the process of improving taxonomy and discovering species is not well understood. Here I investigate in detail the taxonomy and process of species discovery in a genus of tropical plants, Aframomum by examining specimens, taxonomic literature and authors of specimen determinations. I demonstrate that &GT;50&percnt; of Aframomum specimens did not have the correct name prior to a recent comprehensive revision, that the number of specimens in herbaria doubled between 1970 and 2000, and that these results are also found in other taxa. I deconstruct the process of ‘species discovery' by identifying four key events: Initial collection, publication, conservation assessment, and distribution mapping. The time lags between the initial collection and completion of a) an accurate conservation assessment (101 years) and b) a comprehensive distribution map (115 years) demonstrate that many seed plant species published in the last 100 years are not fully understood. This is partly due to the fact that most species protologues (&GT;90&percnt;) cite too few specimens at publication to produce an accurate conservation assessment. Furthermore, I explore variation in species' distribution patterns over time, taking account of specimen misidentification. Taken together the thesis identifies the lack of taxonomic capacity to efficiently deal with the tremendous influx of specimens since 1970, the poor current state of taxonomic knowledge of many taxa, and three significant time lags in the process of species discovery. Focused taxonomic effort is required for the successful completion of a world online Flora with conservation assessments to meet the 2020 GSPC target.

The inference of species boundaries and phylogenetic relationships are fundamental for evolutionary, ecological, and conservation studies. The resolution of species boundaries and the inference of phylogenetic relationships among species are required to define the units of analysis and to find the most closely related units for evaluating alternative models of speciation. I highlight lizards as model organisms for ecological and evolutionary studies, emphasizing their contributions to advances in understanding linkages between phylogeography and speciation. In this dissertation, I focus on the phylogenetic relationships of the lizards in the Liolaemus darwinii group, and the species boundaries of a nested clade within the group, the L. darwinii complex, because of several advantages that make these taxa ideal for phylogeographic studies of speciation. I infer a phylogeny for the L. darwinii group based on DNA sequences of 20 loci (19 nuclear and 1 mitochondrial) using species trees methods that take into account the incongruence among gene trees. I found the minimum number of loci, number of sequences per species, and number of base pairs per locus that should be included in an analysis for an accurate and precise estimate of the species tree. The species tree based on all available data support a clade of closely related species (L. darwinii, L. grosseorum, and L. laurenti) known as the L. darwinii complex. A new method for species delimitation using Approximate Bayesian Computation is introduced and is shown to accurately delimit species given that limited or no gene flow has occurred after divergence and despite biased estimates of demographic parameters. ABC analyses supported the distinctness of two lineages within L. darwinii under a model of speciation with gene flow. Based on the species tree and the species limits obtained in this dissertation, phylogenetic comparative methods can be carried out to address the morphological and ecological evolution in the L. darwinii group and several sister species can be used for testing the alternative speciation models via correlation analyses of genetic, morphological, and ecological datasets. Future studies should assess the role speciation due to adaptive processes and its association the species' ecological niches and life histories.