Browsing RESEARCH: Robertson, M by Title
Now showing items 1-20 of 47
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Alien plant species that invade high elevations are generalists: support for the directional ecological filtering hypothesis
(International Association for Vegetation Science, 2017)Questions: The richness of invasive alien plant species tends to decrease with increasing elevation. This pattern may be due to alien plant species requiring traits allowing survival at high elevations (the Abiotic ... -
Alnus glutinosa (Betulaceae) in South Africa: invasive potential and management options
(2020)Invasive alien plants cause major environmental and economic impacts and preventing the establishment and spread of emerging invaders is crucial. Black Alder (Alnus glutinosa) is well established as a widespread invader ... -
Annual monitoring reveals rapid upward movement of exotic plants in a montane ecosystem
(Springer, 2015)There is increasing evidence that invasive species are threating montane ecosystems globally. However, trends in species distribution are difficult to observe directly due to a lack of data with suitable spatio-temporal ... -
Ant assemblages have darker and larger members in cold environments
(John Wiley & Sons Ltd, 2016)Aim In ectotherms, the colour of an individual’s cuticle may have important thermoregulatory and protective consequences. In cool environments, ectotherms should be darker, to maximize heat gain, and larger, to minimize ... -
An assessment of rehabilitation success in an African grassland using ants as bioindicators
(AOSIS, 2016)Many studies that evaluate rehabilitation make use of invertebrate bioindicators. Invertebrates, especially ants, make useful indicators as they are sensitive to environmental change. We compared ant assemblages in ... -
An assessment of the information content of South African alien species databases
(AOSIS Publishing, 2015)National alien species databases indicate the state of a country’s biodiversity and provide useful data for research on invasion biology and the management of invasions. In South Africa there are several different published ... -
The balance of trade in alien species between South Africa and the rest of Africa
(AOSIS, 2017)Background: Alien organisms are not only introduced from one biogeographical region to another but also spread within regions. As South Africa shares land borders with six countries, multiple opportunities exist for the ... -
Biogeo: an R package for assessing and improving data quality of occurrence record datasets
(Nordic Society Oikos, 2016)Occurrence data from museum and herbarium collections are valuable for mapping biodiversity patterns in space and time. Unfortunately these collections datasets contain many errors and suffer from several data quality ... -
Border control for stowaway alien species should be prioritised based on variations in establishment debt
(Elsevier Ltd, 2016)Border control is one of the major approaches used by countries to limit the number of organisms introduced as stowaways. However, it is not feasible to inspect all passengers, cargo and vehicles entering a country, and ... -
Classifying the introduction pathways of alien species: are we moving in the right direction?
(2020)Alien species are introduced to new regions in many different ways and for different purposes. A number of frameworks have been developed to group such pathways of introduction into discrete categories in order to improve ... -
Contrasting species and functional beta diversity in montane ant assemblages
(John Wiley & Sons Ltd, 2015)Aim Beta diversity describes the variation in species composition between sites and can be used to infer why different species occupy different parts of the globe. It can be viewed in a number of ways. First, it can be ... -
Coping with the cold: minimum temperatures and thermal tolerances dominate the ecology of mountain ants
(John Wiley & Sons Ltd, 2017)1. Ants (Hymenoptera: Formicidae) are often cited as highly thermophilic and this has led to a range of studies investigating their thermal tolerances. It is unknown, however, if the geographic distribution of ant thermal ... -
Double trouble: the implications of climate change for biological invasions
(2020)The implications of climate change for biological invasions are multifaceted and vary along the invasion process. Changes in vectors and pathways are likely to manifest in changes in transport routes and destinations, ... -
Ecological niche modeling of the invasive potential of Nile tilapia Oreochromis niloticus in African river systems: concerns and implications for the conservation of indigenous congenerics
(2013-06-30)This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and ... -
Elevation–diversity patterns through space and time: ant communities of the Maloti-Drakensberg Mountains of southern Africa
(John Wiley & Sons Ltd, 2014)Aim Patterns of biological diversity are often investigated across space but little work has attempted to explore the consistency of such observations through time. Here, our aim was to understand the patterns of diversity ... -
Evaluating habitat connectivity methodologies: a case study with endangered African wild dogs in South Africa
(Springer, 2016)Context In fragmented landscapes, connectivity between subpopulations is vital for species’ persistence. Various techniques are used to assess the degree of connectivity between habitat patches, yet their performance is ... -
Forestry trial data can be used to evaluate climate-based species distribution models in predicting tree invasions
(Pensoft Publishers, 2014)Climate is frequently used to predict the outcome of species introductions based on the results from species distribution models (SDMs). However, despite the widespread use of SDMs for pre- and post-border risk assessments, ... -
The historical distribution of megaherbivores does not determine the distribution of megafaunal fruit in southern Africa
(2019)Large specialized fruit (megafaunal fruit) have evolved alongside megaherbivores to take advantage of their unparalleled seed dispersal service. Megaherbivores were widespread and abundant in the Pleistocene but due to ... -
Introduced and invasive cactus species: a global review
(Oxford University Press, 2015)Understanding which species are introduced and become invasive, and why, are central questions in invasion science. Comparative studies on model taxa have provided important insights, but much more needs to be done to ... -
Invasion debt – quantifying future biological invasions
(John Wiley & Sons Ltd, 2016)Aim We develop a framework for quantifying invasions based on lagged trends in invasions (‘invasion debt’) with the aim of identifying appropriate metrics to quantify delayed responses at different invasion stages – from ...