Steven L Chown

Steven L Chown
Monash University (Australia) · School of Biological Sciences, Clayton

Ph.D.

About

490
Publications
91,433
Reads
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30,661
Citations
Additional affiliations
July 2012 - present
Monash University (Australia)
June 2004 - June 2012
Stellenbosch University
January 2002 - May 2004
Education
February 1986 - August 1989
University of Pretoria
Field of study
  • Entomology

Publications

Publications (490)
Article
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Background: The intense interactions between people, animals and environmental systems in urban informal settlements compromise human and environmental health. Inadequate water and sanitation services, compounded by exposure to flooding and climate change risks, expose inhabitants to environmental contamination causing poor health and wellbeing and...
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Desert soils harbour diverse communities of aerobic bacteria despite lacking substantial organic carbon inputs from vegetation. A major question is therefore how these communities maintain their biodiversity and biomass in these resource-limiting ecosystems. Here, we investigated desert topsoils and biological soil crusts collected along an aridity...
Article
Ectotherms may respond to variable environmental conditions by altering their phenotypes. Phenotypic plasticity was initially thought to be beneficial to an organism's physiological fitness but several alternative hypotheses have been proposed with growing empirical support. In this study, we tested the full suite of hypotheses by investigating acc...
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On page 234 of this Perspective, '50% decrease' has been corrected online to '50% increase' in the sentence "The pH of surface waters south of 60° S decreased by 0.2 between 2017 and 2070, equivalent to a 50% increase in the concentration of hydrogen ions since the pre-industrial period1."
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Traits of thermal sensitivity or performance are typically the focus of species distribution modelling. Among-population trait variation, trait plasticity, population connectedness and the possible climatic covariation thereof are seldom accounted for. Here, we examine multiple climate stress resistance traits, and the plasticity thereof, for a glo...
Article
We present two narratives on the future of Antarctica and the Southern Ocean, from the perspective of an observer looking back from 2070. In the first scenario, greenhouse gas emissions remained unchecked, the climate continued to warm, and the policy response was ineffective; this had large ramifications in Antarctica and the Southern Ocean, with...
Article
Collembola are an important group of indigenous terrestrial invertebrates in the sub-Antarctic region and, compared to the most continental regions, their limited diversity is well known. Several invasive species, introduced by humans, have also established in the region, with some of these widespread while others are more restricted to disturbed a...
Article
Extreme and remote environments provide useful settings to test ideas about the ecological and evolutionary drivers of biological diversity. In the sub-Antarctic, isolation by geographic, geological and glaciological processes has long been thought to underpin patterns in the region's terrestrial and marine diversity. Molecular studies using increa...
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The Strategic Plan for Biodiversity, adopted under the auspices of the Convention on Biological Diversity, provides the basis for taking effective action to curb biodiversity loss across the planet by 2020—an urgent imperative. Yet, Antarctica and the Southern Ocean, which encompass 10% of the planet’s surface, are excluded from assessments of prog...
Article
Physiological ecologists have long assumed that thermoregulatory behaviour will evolve to optimise physiological performance. The coadaptation hypothesis predicts that an animal's preferred body temperature will correspond to the temperature at which its performance is optimal. Here we use a strong inference approach to examine the relationship bet...
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The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements in...
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Land-use change may alter both species diversity and species functional diversity patterns. To test the idea that species diversity and functional diversity changes respond in differing ways to land-use changes, we characterize the form of the change in bird assemblages and species functional traits along an intensifying gradient of land use in the...
Article
Elucidating the mechanisms responsible for the structure of urban communities is a key aim of urban ecology, but one that is often confounded by the multitude of environmental changes that are caused by urbanisation. We applied trait-based techniques to identify the specific environmental drivers that shape urban plant assemblages and predict how t...
Article
Air temperatures have increased globally over the past decades, while rainfall changes have been more variable, but are taking place. In South Africa, substantial climate-related impacts are predicted, and protected area management agencies will need to respond actively to impacts. It is critical for management agencies to understand the way in whi...
Article
Understanding the influence of microclimates is an increasing focus of investigations of global change risks to insects. Here we review recent advances in this area in the context of macrophysiological forecasts of the impacts of warming. Some studies have suggested that risk estimates may be inaccurate owing to microclimate variation or behavioura...
Article
Given global climate change, much attention has been given to the extent to which upper thermal tolerance limits in terrestrial and marine metazoans might be constrained. A quantitative synthesis of the available information indicates that aquatic insects, and especially immature life stages, have a broader range of thermal tolerances, and a lower...
Article
Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate - temperature relationship. Moreover, assessmen...
Article
On sub-Antarctic Marion Island, wandering albatross ( Diomedea exulans ) nests support high abundances of tineid moth, Pringleophaga marioni , caterpillars. Previous work proposed that the birds serve as thermal ecosystem engineers by elevating nest temperatures relative to ambient, thereby promoting growth and survival of the caterpillars. However...
Article
The Arctic and Antarctic polar regions are subject to multiple environmental threats, arising from both local and ex-situ human activities. We review the major threats to polar ecosystems including the principal stressor, climate change, which interacts with and exacerbates other threats such as pollution, fisheries overexploitation, and the establ...
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Understanding the spatial distribution of organisms and the factors underlying it are key questions in ecology. Two competing hypotheses exist about the form of spatial variation in abundance. The abundant centre hypothesis suggests that abundance is highest in the centre of a species’ range and declines towards the range margins. By contrast, the...
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Although significant progress has been made using insect taxa as model organisms, non-tracheated terrestrial arthropods, such as Collembola, are underrepresented as model species. This underrepresentation reflects the difficulty in maintaining populations of specialist Collembola species in the laboratory. Until now, no species from the family Nean...
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Macrophysiology is the investigation of variation in physiological traits over large geographic and temporal scales and the ecological implications of this variation. It has now been undertaken, as a defined field, for a decade.Here we overview its conceptual foundations, methodological approaches and insights, together with challenges the field is...
Article
Antarctic biodiversity is much more extensive, ecologically diverse and biogeographically structured than previously thought. Understanding of how this diversity is distributed in marine and terrestrial systems, the mechanisms underlying its spatial variation, and the significance of the microbiota is growing rapidly. Broadly recognizable drivers o...
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Biological invasion is one of the key threats to the conservation of the broader Antarctic region. We provide an evidence-based assessment of the status of biological invasion in the region as a basis for future monitoring and management. We adapted the indicator framework for global biological invasion monitoring by collating information on (i) nu...
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Understanding the abundance and richness of species is one of the most fundamental steps in effecting their conservation. Despite global recognition of the significance of the below-ground component of diversity for ecosystem functioning, the soil remains a poorly studied terrestrial ecosystem. In South Africa, knowledge is increasing for a variety...
Article
More than 50% of the global human population lives in urban settings, which, for urban agglomerations with >1 million inhabitants, span a 30 °C range in mean annual temperature and 4000 mm annual precipitation range.Although the biodiversity impacts of urbanization are most commonly investigated at the assemblage level, these impacts are mediated t...
Article
Evidence-based assessments are increasingly recognized as the best-practice approach to determine appropriate conservation interventions, but such assessments of the impact of human disturbance on wildlife are rare. Human disturbance comprises anthropogenic activities that are typically non-lethal, but may cause short- and/or longer-term stress and...
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Biological invasions are major threats to biodiversity, with impacts that may be compounded by other forms of environmental change. Observations of high density of the invasive springtail (Collembola), Hypogastrura manubrialis in heavily grazed renosterveld vegetation in the Western Cape, South Africa, raised the question of whether the invasion wa...
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The distribution of the Southern Ocean nearshore marine benthic fauna is the consequence of major geologic, oceanographic, and climatic changes during the last 50 Ma. As a result, a main biogeographic principle in the Southern Ocean is the clear distinction of the Antarctic biota. The Antarctic Polar Front (APF) represents an important barrier betw...
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The rate of biological invasions is expected to increase as the effects of climate change on biological communities become widespread. Climate change enhances habitat disturbance which facilitates the establishment of invasive species, which in turn provides opportunities for hybridization and introgression. These effects influence local biodiversi...
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Adult mosquito survival is strongly temperature and moisture dependent. Few studies have investigated the interacting effects of these variables on adult survival and how this differs among the sexes and with age, despite the importance of such information for population dynamic models. For these reasons, the desiccation tolerance of Anopheles arab...
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Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the hor...
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Terrestrial protected areas (PAs) are cornerstones of global biodiversity conservation. Their efficacy in terms of maintaining biodiversity is, however, much debated. Studies to date have been unable to provide a general answer as to PA conservation efficacy because of their typically restricted geographic and/or taxonomic focus, or qualitative app...
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Mahlon C. Kennicutt II, Steven L. Chown and colleagues outline the most pressing questions in southern polar research, and call for greater collaboration and environmental protection in the region.
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Full list of co-signatories for Nature Comment "Polar research: Six priorities for Antarctic science"
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Horizon scan methodologies 1,2,3,4 were customized for the Antarctic Science Horizon Scan aiming for broad community engagement and transparent decision-making. A database of 866 scientific questions was generated by two open community-wide, on-line solicitations. Submitted questions were expected to: i) be answerable by an achievable research desi...
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Mahlon C. Kennicutt II, Steven L. Chown and colleagues outline the most pressing questions in southern polar research, and call for greater collaboration and environmental protection in the region.
Article
The evolutionary origin and maintenance of discontinuous gas exchange (DGE) in tracheate arthropods are poorly understood and highly controversial. We investigated prioritisation of abiotic factors in the gas exchange control cascade by examining oxygen, water and haemolymph pH regulation in the grasshopper Paracinema tricolor. Using a full-factori...
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Antarctica is widely regarded as one of the planet's last true wildernesses, insulated from threat by its remoteness and declaration as a natural reserve dedicated to peace and science. However, rapidly growing human activity is accelerating threats to biodiversity. We determined how well the existing protected-area system represents terrestrial bi...
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Distinguishing between species that are recent natural colonists, recent anthropogenic introductions, or previously unknown, but long-term resident native species, is a challenge for those who manage the conservation of the Antarctic region. Here, we report the discovery of two new arthropod species on sub-Antarctic Marion Island—Nabis capsiformis...
Article
Patterns of environmental spatial structure lie at the heart of the most fundamental and familiar patterns of diversity on Earth. Antarctica contains some of the strongest environmental gradients on the planet and therefore provides an ideal study ground to test hypotheses on the relevance of environmental variability for biodiversity. To answer th...
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On the South Indian Ocean Province Islands of the sub-Antarctic, most nutrients are processed through a detritus-based food web. On Marion Island, larvae of the moth Pringleophaga marioni are one of the key decomposers. Abundance of these caterpillars is higher in newly abandoned Wandering Albatross (Diomedea exulans) nests than other habitats, and...
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This study examined high temperature survival and heat shock protein 70 (Hsp70) responses to temperature variation for two marine invertebrate species on sub-Antarctic Marion Island. The isopod Exosphaeroma gigas Leach and the amphipod Hyale hirtipalma Dana had the same tolerance to high temperature. The mean upper temperature which was lethal for...
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The weevil Cyrtobagous salviniae Calder & Sands 1985 (Family: Curculionidae) is a highly effective biocontrol agent for the invasive water fern Salvinia molesta D.S. Mitchell (Family: Salviniaceae). The life histories of both organisms are affected by temperature, making the potential impacts of climate change on efficacy of control an important ar...
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Climate change has played a critical role in the evolution and structure of Earth's biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this "geothermal glacial refugia" hypothesis has...
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Despite considerable research on biological invasions, key areas remain poorly explored, especially ways to reduce unintentional propagule transfer. The Antarctic represents a microcosm of the situation, with the numbers of established non-native species growing. Information to help reduce potential impacts is therefore critical. We measured the pr...
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AimAltered habitats may form entirely novel ecosystems that support new combinations of species. How indigenous species use invaded areas is, however, not well understood. Here, we investigate the value of Australian Acacia thickets as novel ecosystems in the Western Cape of South Africa by surveying bird assemblages within them. LocationWestern Ca...
Chapter
South Africa has a long history of human-mediated introductions of species from all major taxonomic groups. Close to 9000 alien terrestrial plant species have been introduced, and all of the country's biomes have already been invaded. Invasive species are threatening the country's ecosystems in numerous ways, but the effect of climate change on the...
Article
Understanding the extent to which organisms are affected by climate change and are capable of adapting to warming is essential for managing biodiversity. Recent macrophysiological analyses suggest that range-related responses to warming may be more coherent (less variable) and predictable in marine than in terrestrial systems.To examine this genera...
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AimDespite their potentially profound consequences, little is known about the impacts of interactions among environmental change drivers on indigenous species. For biological invasions, much theoretical prominence has been given to additive or synergistic interactions with temperature change. However, empirical investigations are sparse. Here, we i...
Article
Quaternary glaciations in Antarctica drastically modified geographical ranges and population sizes of marine benthic invertebrates and thus affected the amount and distribution of intraspecific genetic variation. Here, we present new genetic information in the Antarctic limpet Nacella concinna, a dominant Antarctic benthic species along shallow ice...
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Climate change is altering phenology and distributions of many species and further changes are projected. Can species physiologically adapt to climate warming? We analyse thermal tolerances of a large number of terrestrial ectotherm (n = 697), endotherm (n = 227) and plant (n = 1816) species worldwide, and show that tolerance to heat is largely con...
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Thermal trait variation is of fundamental importance to forecasting the impacts of environmental change on lizard diversity. Here, we review the literature for patterns of variation in traits of upper and lower sub-lethal temperature limits, temperature preference and active body temperature in the field, in relation to space, time and phylogeny. T...
Article
In the globally significant, lowland terrestrial systems of the sub-Antarctic's South Indian Ocean Province Islands, caterpillars of the flightless moth genus Pringleophaga (Lepidoptera: Tineidae) are typically responsible for much nutrient turnover.On Marion Island, Pringleophaga marioni is a keystone species for this reason.Rising temperatures ha...
Article
1. Terrestrial ectotherms are likely to face increased periods of heat stress as mean temperatures and temperature variability increase over the next few decades. Here, we consider the extent to which changes in upper thermal limits, through plasticity or evolution, might be constrained, and we survey insect and reptile data to identify groups like...
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