Magister Scientiae (Biodiversity and Conservation Biology)
The spread of invasive species is one of the greatest threats to global biodiversity. Alien plant invasions also have serious economic ...impact in terms of the delivery of ecosystem goods and services. Studies of biological invasions in southern Africa have tended to overlook grasses (family Poaceae), although there are many naturalised species in the region. Only a few of these, all perennials, have been officially categorised as invasive in South Africa, but in the winter rainfall region of the Western Cape, grass invasion especially by Mediterranean European annuals have also been noted. These grasses can be difficult to identify. DNA barcoding has been suggested as an alternative method of identifying grasses in the hope of facilitating identification of existing invaders and preventing future invasions. In this study a list of all known naturalised grasses in South Africa was compiled, and a DNA barcoding reference database was assembled for these naturalised grass species as well as for native southern African grass species. The two official markers for plant DNA barcoding (rbcLa + matK) were used in barcoding and phylogenetic analyses, both individually and in combination. The barcoding data was assessed for identification efficacy using three distance-based metrics and one tree-based metric in the R package SPIDER, both including and excluding singleton data. This study lists 128 naturalised grass species and subspecies found in South Africa. In the DNA barcoding analyses, matK was found to perform better as a single barcode than rbcLa, with identification success rates of up to 84% for matK and 76% for rbcLa, using the most successful metric which was the Nearest Neighbour criterion for both of these markers in the data sets without singletons. The combined rbcLa + matK data set performed better than either of the two individual markers, with identification success rates of up to 91% in the data without singletons, with the most successful metric again being the Nearest Neighbour criterion. The combined rbcLa + matK data would therefore be the recommended DNA barcode for southern African grasses of the three data sets tested, based on the results of this study. Phylogenetic trees were constructed with the DNA barcoding data using Bayesian Inference (BI) and Maximum Parsimony (MP) to assess the usefulness of the data in phylogenetic studies and to confirm the efficacy of this grass DNA barcoding data when using tree-based methods of identification. Both the matK and combined datasets resolved all of the grass tribes represented in this study as monophyletic, but the rbcLa data did not.
A contemporary case-based discussion of ethical dilemmas faced by researchers in forensic mental health, this book offers useful guidance to anyone planning research in this field. It focuses on ...problems frequently encountered, such as issues of capacity to consent in forensic settings and the meaning of consent to participate. Chapters cover issues such as the procurement of consent among incarcerated people; the ability of young people to provide consent; the effects of culturally specific lay beliefs about mental illness; confidentiality; multidisciplinary approaches; and ethics in risk assessment research. The contributors address questions such as whether research can be therapeutic, and whether it is ever reasonable to compromise patient confidentiality for the wider benefits of publishing research. Based on empirical data from researchers' own experiences, this comprehensive book will be essential reading for anyone planning research in the area of forensic mental health, and all whose work is in this area.
High schools in the United States are increasingly requiring their students to complete financial education prior to graduation. This study estimates the effects of these requirements on the credit ...report outcomes of 18- through 21-year-olds—young people just establishing their financial independence. We find that financial education requirements are associated with fewer defaults and higher credit scores among young adults, but this general finding masks important heterogeneity at the state level. We conclude that well-funded teacher preparation may be key to successfully implementing financial education programs.
Background and Aims Root traits are increasingly used to predict how plants modify soil processes. Here, we assessed how drought-induced changes in root systems of four common grassland species ...affected C and N availability in soil. We hypothesized that drought would promote resource-conservative root traits such as high root tissue density (RTD) and low specific root length (SRL), and that these changes would result in higher soil N availability through decreased root N uptake, but lower C availability through reduced root exudation. Methods We subjected individual plants to drought under controlled conditions, and compared the response of their root biomass, root traits, and soil C and N availability, to control individuals. Results Drought affected most root traits through reducing root biomass. Only SRL and RTD displayed plasticity; drought reduced SRL, and increased RTD in small plants but decreased RTD in larger plants. Reduced root biomass and a shift towards more resource-conservative root traits increased soil inorganic N availability but did not directly affect soil C availability. Conclusions These findings identify mechanisms through which drought-induced changes in root systems affect soil C and N availability, and contribute to our understanding of how root traits modify soil processes in a changing world.
Background
The most recent meta-analytic review of injuries in elite senior men’s Rugby Union was published in 2013. The demands of the game at the elite level are continually changing alongside law ...amendments and developments in player preparation. As such, an updated meta-analysis of injury data in this setting is necessary.
Objective
To meta-analyse time-loss injury data in elite senior men’s Rugby Union between 2012 and 2020.
Methods
Electronic databases were searched using the keywords ‘rugby’ and ‘inj*’. Nineteen studies met the inclusion criteria. Injury incidence rate data were modelled using a mixed-effects Poisson regression model. Days missed data were modelled using a general linear mixed model.
Results
The included data encompassed a total of 8819 match injuries and 2801 training injuries. The overall incidence rate of injuries in matches was 91 per 1000 h (95% confidence interval (CI) 77–106). The estimated mean days missed per match injury was 27 days (95% CI 23–32). The overall incidence rate of match concussions was 12 per 1000 h (95% CI 9–15). The overall incidence rate of training injuries was 2.8 per 1000 h (95% CI 1.9–4.0). Playing level was not a significant effect modifier for any outcome.
Conclusions
The injury incidence rate and mean days missed per injury in the present meta-analysis were higher, but statistically equivalent to, the 2013 meta-analysis (81 per 1000 h and 20 days, respectively). The injury incidence rate for match injuries in elite senior men’s Rugby Union is high in comparison to most team sports, though the training injury incidence rate compares favourably. The tackle event and concussion injuries should continue to be the focus of future preventative efforts.
Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient ...addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.
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