The biogeography of South African terrestrial plant invasions

Thousands of plant species have been introduced, intentionally and accidentally, to South Africa from many parts of the world. Alien plants are now conspicuous features of many South African landscapes and hundreds of species have naturalised (i.e. reproduce regularly without human intervention), many of which are also invasive (i.e. have spread over long distances). There is no comprehensive inventory of alien, naturalised, and invasive plants for South Africa, but 327 plant taxa, most of which are invasive, are listed in national legislation. We collated records of 759 plant taxa in 126 families and 418 genera that have naturalised in natural and semi-natural ecosystems. Over half of these naturalised taxa are trees or shrubs, just under a tenth are in the families Fabaceae (73 taxa) and Asteraceae (64); genera with the most species are Eucalyptus,Acacia, and Opuntia. The southern African Plant Invaders Atlas (SAPIA) provides the best data for assessing the extent of invasions at the national scale. SAPIA data show that naturalised plants occur in 83% of quarter-degree grid cells in the country. While SAPIA data highlight general distribution patterns (high alien plant species richness in areas with high native plant species richness and around the main human settlements), an accurate, repeatable method for estimating the area invaded by plants is lacking. Introductions and dissemination of alien plants over more than three centuries, and invasions over at least 120 years (and especially in the last 50 years) have shaped the distribution of alien plants in South Africa. Distribution patterns of naturalised and invasive plants define four ecologically-meaningful clusters or “alien plant species assemblage zones”, each with signature alien plant taxa for which trait-environment interactions can be postulated as strong determinants of success. Some widespread invasive taxa occur in high frequencies across multiple zones; these taxa occur mainly in riparian zones and other azonal habitats,or depend on human-mediated disturbance, which weakens or overcomes the factors that determine specificity to any biogeographical region

Conserved expression and functions of PDE4 in rodent and human heart

PDE4 isoenzymes are critical in the control of cAMP signaling in rodent cardiac myocytes. Ablation of PDE4 affects multiple key players in excitation–contraction coupling and predisposes mice to the development of heart failure. As little is known about PDE4 in human heart, we explored to what extent cardiac expression and functions of PDE4 are conserved between rodents and humans. We find considerable similarities including comparable amounts of PDE4 activity expressed, expression of the same PDE4 subtypes and splicing variants, anchoring of PDE4 to the same subcellular compartments and macromolecular signaling complexes, and downregulation of PDE4 activity and protein in heart failure. The major difference between the species is a fivefold higher amount of non-PDE4 activity in human hearts compared to rodents. As a consequence, the effect of PDE4 inactivation is different in rodents and humans. PDE4 inhibition leads to increased phosphorylation of virtually all PKA substrates in mouse cardiomyocytes, but increased phosphorylation of only a restricted number of proteins in human cardiomyocytes. Our findings suggest that PDE4s have a similar role in the local regulation of cAMP signaling in rodent and human heart. However, inhibition of PDE4 has ‘global’ effects on cAMP signaling only in rodent hearts, as PDE4 comprises a large fraction of the total cardiac PDE activity in rodents but not in humans. These differences may explain the distinct pharmacological effects of PDE4 inhibition in rodent and human hearts

The extent and effectiveness of alien plant control projects in South Africa

CITATION: van Wilgen, B.W. et al. 2020. The extent and effectiveness of alien plant control projects in South Africa. In: Biological Invasions in South Africa. van Wilgen, B.W., Measey, J., Richardson, D.M., Wilson, J.R. and Zengeya, T.A. (eds.). Springer, Cham:597-628. doi:10.1007/978-3-030-32394-3_21The original publication is available at https://link.springer.com/book/10.1007/978-3-030-32394-3Studies of the impact of alien species on the environment are increasingly being carried out, and there has been ongoing debate about how to standardise the description of these impacts. This chapter evaluates the state of knowledge on the impacts of alien species on biodiversity in South Africa based on different assessment methods. Despite South Africa being one of the most biologically diverse countries in the world, there have been very few studies that formally document the impacts of alien species on biodiversity. Most of what is known is based on expert opinion, and consequently the level of confidence in the estimates of the magnitude of these impacts is low. However, it is clear that a significant number of alien species cause major negative impacts, and that there is cause for serious concern. There is a growing global effort to assess all alien species with standardised protocols to alleviate the problem of comparing impacts measured using different approaches. Formal assessments have been done for a few alien species in South Africa, but most naturalised and invasive species have not been evaluated, and, we suspect, for most alien species there has been no attempt, as yet, to document their impacts. However, red-listing processes found that alien species were frequently included as a significant extinction risk for several native species of fish, amphibians, and plants. There are very few studies that cover the combined impacts of co-occurring alien species in particular areas, and these studies could provide the rationale for regulation and management, which is often absent. While reductions due to alien species in the value of ecosystem services, the productivity of rangelands, and biodiversity intactness are relatively low at present these impacts are expected to grow rapidly as more invasive species enter a stage of exponential growth.https://link.springer.com/chapter/10.1007%2F978-3-030-32394-3_21Publisher’s versio

Biological Invasions and Ecological Restoration in South Africa

This chapter provides an overview of the researchers and research initiatives relevant to invasion science in South Africa over the past 130 years, profiling some of the more recent personalities, particularly those who are today regarded as international leaders in the field. A number of key points arise from this review. Since 1913, South Africa has been one of a few countries that have investigated and implemented alien plant biological control on a large scale, and is regarded as a leader in this field. South Africa was also prominent in the conceptualisation and execution of the international SCOPE project on the ecology of biological invasions in the 1980s, during which South African scientists established themselves as valuable contributors to the field. The development of invasion science benefitted from a deliberate strategy to promote multi-organisational, interdisciplinary research in the 1980s. Since 1995, the Working for Water programme has provided funding for research and a host of practical questions that required research solutions. Finally, the establishment of a national centre of excellence with a focus on biological invasions has made a considerable contribution to building human capacity in the field, resulting in advances in all aspects of invasion science—primarily in terms of biology and ecology, but also in history, sociology, economics and management. South Africa has punched well above its weight in developing the field of invasion science, possibly because of the remarkable biodiversity that provided a rich template on which to carry out research, and a small, well-connected research community that was encouraged to operate in a collaborative manner

Biological Invasions in South Africa's Urban Ecosystems: Patterns, Processes, Impacts and Management

This chapter provides an overview of the researchers and research initiatives relevant to invasion science in South Africa over the past 130 years, profiling some of the more recent personalities, particularly those who are today regarded as international leaders in the field. A number of key points arise from this review. Since 1913, South Africa has been one of a few countries that have investigated and implemented alien plant biological control on a large scale, and is regarded as a leader in this field. South Africa was also prominent in the conceptualisation and execution of the international SCOPE project on the ecology of biological invasions in the 1980s, during which South African scientists established themselves as valuable contributors to the field. The development of invasion science benefitted from a deliberate strategy to promote multi-organisational, interdisciplinary research in the 1980s. Since 1995, the Working for Water programme has provided funding for research and a host of practical questions that required research solutions. Finally, the establishment of a national centre of excellence with a focus on biological invasions has made a considerable contribution to building human capacity in the field, resulting in advances in all aspects of invasion science—primarily in terms of biology and ecology, but also in history, sociology, economics and management. South Africa has punched well above its weight in developing the field of invasion science, possibly because of the remarkable biodiversity that provided a rich template on which to carry out research, and a small, well-connected research community that was encouraged to operate in a collaborative manner

Moderators of exercise effects on cancer-related fatigue: a meta-analysis of individual patient data

Purpose: Fatigue is a common and potentially disabling symptom in patients with cancer. It can often be effectively reduced by exercise. Yet, effects of exercise interventions might differ across subgroups. We conducted a meta-analysis using individual patient data of randomized controlled trials (RCT) to investigate moderators of exercise intervention effects on cancer-related fatigue. Methods: We used individual patient data from 31 exercise RCT worldwide, representing 4366 patients, of whom 3846 had complete fatigue data. We performed a one-step individual patient data meta-analysis, using linear mixed-effect models to analyze the effects of exercise interventions on fatigue (z score) and to identify demographic, clinical, intervention- A nd exercise-related moderators. Models were adjusted for baseline fatigue and included a random intercept on study level to account for clustering of patients within studies. We identified potential moderators by testing their interaction with group allocation, using a likelihood ratio test. Results: Exercise interventions had statistically significant beneficial effects on fatigue (β =-0.17; 95% confidence interval [CI],-0.22 to-0.12). There was no evidence of moderation by demographic or clinical characteristics. Supervised exercise interventions had significantly larger effects on fatigue than unsupervised exercise interventions (βdifference =-0.18; 95% CI-0.28 to-0.08). Supervised interventions with a duration ≤12 wk showed larger effects on fatigue (β =-0.29; 95% CI,-0.39 to-0.20) than supervised interventions with a longer duration. Conclusions: In this individual patient data meta-analysis, we found statistically significant beneficial effects of exercise interventions on fatigue, irrespective of demographic and clinical characteristics. These findings support a role for exercise, preferably supervised exercise interventions, in clinical practice. Reasons for differential effects in duration require further exploration