Stephen E Williams

Stephen E Williams
James Cook University · Centre For Tropical Biodiversity and Climate Change

PhD

About

165
Publications
81,010
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29,889
Citations
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January 2012 - present
January 2011 - present
January 2011 - present

Publications

Publications (165)
Article
Full-text available
Invasive mesopredators are responsible for the decline of many species of native mammals worldwide. Feral cats have been causally linked to multiple extinctions of Australian mammals since European colonization. While feral cats are found throughout Australia, most research has been undertaken in arid habitats, thus there is a limited understanding...
Article
Full-text available
Aim Climate change is driving species to migrate to novel areas as current environments become unsuitable. As a result, species distributions have shifted uphill in montane ecosystems globally. Heterogeneous dispersal rates among shifting species could result in complex changes to community assemblages. For example, interspecific differences in dis...
Article
Full-text available
Many authors have suggested that the vulnerability of montane biodiversity to climate change worldwide is significantly higher than in most other ecosystems. Despite the extensive variety of studies predicting severe impacts of climate change globally, few studies have empirically validated the predicted changes in distribution and population densi...
Article
Full-text available
Species are not uniformly distributed across the landscape. For every species, there should be few favoured sites where abundance is high and many other sites of lower suitability where abundance is low. Consequently, local abundance could be thought of as a natural expression of species response to local conditions. The correlation between abundan...
Article
Determining how species thermal limits correlate with climate is important for understanding biogeographic patterns and assessing vulnerability to climate change. Such analyses need to consider thermal gradients at multiple spatial scales. Here we relate thermal traits of rainforest ants to microclimate conditions from ground to canopy (microgeogra...
Preprint
Full-text available
Many authors have suggested that the vulnerability of montane biodiversity to climate change worldwide is significantly higher than in most other ecosystems. Despite the extensive variety of studies predicting severe impacts of climate change globally, few studies have empirically validated the predicted changes in distribution and population densi...
Article
Full-text available
Aim We propose that forest trees create a vertical dimension for ecological niche variation that generates different regimes of climatic exposure, which in turn drives species elevation distributions. We test this hypothesis by statistically modelling the vertical and elevation distributions and microclimate exposure of rainforest ants. Location W...
Article
Full-text available
Anonychomyrma is a dolichoderine ant genus of cool-temperate Gondwanan origin with a current distribution that extends from the north of southern Australia into the Australasian tropics. Despite its abundance and ecological dominance, little is known of its species diversity and distribution throughout its range. Here, we describe the diversity and...
Article
Full-text available
Species distribution models (SDMs) are widely used to predict and study distributions of species. Many different modeling methods and associated algorithms are used and continue to emerge. It is important to understand how different approaches perform, particularly when applied to species occurrence records that were not gathered in struc­tured sur...
Article
Full-text available
Regional diversity can increase owing to either the packing of species within regional niche space or the expansion of regional niche space. Yet, the primary factors dictating these dynamics remain poorly understood. Here, we assess the relative influence of current environmental conditions (net primary productivity, NPP) versus historic environmen...
Article
Climate change poses significant emerging risks to biodiversity, ecosystem function and associated socioecological systems. Adaptation responses must be initiated in parallel with mitigation efforts, but resources are limited. As climate risks are not distributed equally across taxa, ecosystems and processes, strategic prioritization of research th...
Presentation
Full-text available
The distributions of Nomascus annamensis, N. gabriellae and N. siki in Indochina are an interesting example of how species distributions are influenced by the interactions between bioclimatic gradients and evolutionary history. However, for these gibbon species, the biogeography and evolutionary relationships have not been fully resolved. We used E...
Article
Full-text available
Increases in mean temperatures caused by anthropogenic climate change increase the frequency and severity of temperature extremes. Although extreme temperature events are likely to become increasingly important drivers of species' response to climate change, the impacts are poorly understood owing mainly to a lack of understanding of species’ physi...
Article
Full-text available
Nomascus annamensis is a newly described gibbon endemic to the Indochina peninsula (Cambodia, Laos and Vietnam). We review the published and unpublished literature relevant to N. annamensis to clarify its distribution and help inform conservation management and policy related to this species. The best current distribution estimate for N. annamensis...
Article
The effects of anthropogenic climate change on biodiversity are well known for some high‐profile Australian marine systems, including coral bleaching and kelp forest devastation. Less well‐published are the impacts of climate change being observed in terrestrial ecosystems, although ecological models have predicted substantial changes are likely. D...
Article
According to a prevailing hypothesis, lowland tropical organisms are unlikely to successfully cross mountain passes because they have neither acclimated nor adapted to the colder temperatures found at higher elevations. However, this expectation assumes that changes in temperature are uniform across space and fails to account for the presence of di...
Technical Report
Full-text available
https://www.nccarf.edu.au/sites/default/files/attached_files/NARP_update_Terrestrial_Biodiversity-2017.pdf This document delivers a resource for research providers to identify critical gaps of information needed by sectoral decision-makers; set research priorities based on these gaps, and identify capacity across the network that could be harnesse...
Article
Full-text available
Distributions of Earth’s species are changing at accelerating rates, increasingly driven by human-mediated climate change. Such changes are already altering the composition of ecological communities, but beyond conservation of natural systems, how and why does this matter? We review evidence that climate-driven species redistribution at regional to...
Article
Species that respond favourably to environmental change tend to be mobile or dispersive. Living within trees has some benefits over life on the ground. Species that move vertically within forest canopies can take advantage of increased complexity and resource availability, which should correspond to increased resilience to environmental variability...
Article
The effect of twenty-first-century climate change on biodiversity is commonly forecast based on modelled shifts in species ranges, linked to habitat suitability. These projections have been coupled with species-area relationships (SAR) to infer extinction rates indirectly as a result of the loss of climatically suitable areas and associated habitat...
Article
Full-text available
The effect of twenty-first-century climate change on biodiversity is commonly forecast based on modelled shifts in species ranges, linked to habitat suitability. These projections have been coupled with species-area relationships (SAR) to infer extinction rates indirectly as a result of the loss of climatically suitable areas and associated habitat...
Article
Full-text available
There is pressing urgency to understand how tropical ectotherms can behaviorally and physiologically respond to climate warming. We examine how basking behavior and thermal environment interact to influence evolutionary variation in thermal physiology of multiple species of lygosomine rainforest skinks from the Wet Tropics of northeastern Queenslan...
Book
Full-text available
Predicting climate change impacts on biodiversity is a major scientific challenge, but doing so is important for assessing extinction risk, developing conservation action plans, providing guidance for laws and regulations, and identifying the mechanisms and patterns of impact to inform climate change adaptation. In the few decades since the threat...
Article
Most terrestrial species on Earth are ectothermic and track temperature at small spatial scales, from sun flecks to cool shaded spots. Current assessments of thermal heterogeneity in complex environments are predominately characterized by ambient temperature. This omission of solar radiation may lead to inaccurate conclusions regarding thermoregula...
Article
Full-text available
Morphology mediates the relationship between an organism's body temperature and its environment. Dark organisms, for example, tend to absorb heat more quickly than lighter individuals, which could influence their responses to temperature. Therefore, temperature-related traits such as morphology may affect patterns of species abundance, richness, an...
Article
Full-text available
Understanding how the environment influences patterns of diversity is vital for effective conservation management, especially in a changing global climate. While assemblage structure and species richness patterns are often correlated with current environmental factors, historical influences may also be considerable, especially for taxa with poor di...
Data
Coverage-based rarefaction and extrapolation curves for each subregion. (DOCX)
Data
Summary of flightless ground beetle species. (DOCX)
Data
Pearson correlation coefficients and P values of the 17 predictor variables. (DOCX)
Data
Individual-based rarefaction and extrapolation curves for each subregion. (DOCX)
Article
Full-text available
There is broad consensus that the diversity of functional traits within species assemblages drives several ecological processes. It is also widely recognized that rare species are the first to become extinct following human-induced disturbances. Surprisingly, however, the functional importance of rare species is still poorly understood, particularl...
Data
Understanding how the environment influences patterns of diversity is vital for effective conservation management, especially in a changing global climate. While assemblage structure and species richness patterns are often correlated with current environmental factors, historical influences may also be considerable, especially for taxa with poor di...
Article
Extinction risk for frogs in the Australian wet tropics under a baseline ‘no climate change’ scenario
Article
Extinction risk for frogs in the Australian wet tropics simulated using an extreme Allee effect
Article
Extinction risk for frogs in the Australian wet tropics simulated using an extreme Allee effect
Article
Extinction risk for frogs in the Australian wet tropics under a baseline ‘no climate change’ scenario
Article
Full-text available
Indices of relative abundance do not control for variation in detectability, which can bias density estimates such that ecological processes are difficult to infer. Distance sampling methods can be used to correct for detectability, but in rainforest, where dense vegetation and diverse assemblages complicate sampling, information is lacking about f...
Article
AHTEENSUU ET AL. highlight four issues with our proposed framework for guiding decisions to conserve species under climate change and suggest some ways forward. From the outset we stress that we presented a framework. By their very nature, frameworks are for building on and elaborating. We thus welcome the contribution of Ahteensuu et al.. Here we...
Article
Full-text available
The effects of climate change on biodiversity are increasingly well documented, and many methods have been developed to assess species' vulnerability to climatic changes, both ongoing and projected in the coming decades. To minimize global biodiversity losses, conservationists need to identify those species that are likely to be most vulnerable to...
Technical Report
Full-text available
While gradual changes in climate means will have numerous effects on a range of environmental, social, and economic sectors, emerging evidence shows that many of the environmental, social, and economic impacts of anthropogenic climate change will arise from shifts in the regimes of extreme weather and climatic events, including heat waves, fires, f...
Article
Full-text available
Vegetated habitats contain a variety of fine-scale features that can ameliorate temperate extremes. These buffered microhabitats may be used by species to evade extreme weather and novel climates in the future. Yet, the magnitude and extent of this buffering on a global scale remains unknown. Across all tropical continents and using 36 published st...
Article
Full-text available
To assess a species' vulnerability to climate change, we commonly use mapped environmental data that are coarsely resolved in time and space. Coarsely resolved temperature data are typically inaccurate at predicting temperatures in microhabitats used by an organism and may also exhibit spatial bias in topographically complex areas. One consequence...
Article
Full-text available
The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but othe...
Conference Paper
Full-text available
We model the occurrence of biodiversity as a function of environmental variables to estimate its distribution. This is an alternative to close the gaps of species occurrence information, and to support decision-making. Herein we’ve evaluated the distribution patterns of two dimensions of biodiversity: community composition and species richness for...
Article
Full-text available
The seasonality of litter inputs in forests has important implications for understanding ecosystem processes and biogeochemical cycles. We quantified the drivers of seasonality in litterfall and leaf decomposability using plots throughout the Australian wet tropical region. Litter fell mostly in the summer (wet, warm) months in the region, but othe...
Article
Full-text available
Identifying refugia is a critical component of effective conservation of biodiversity under anthropogenic climate change. However, despite a surge in conceptual and practical interest, identifying refugia remains a significant challenge across diverse continental landscapes. We provide an overview of the key properties of refugia that promote speci...
Article
Full-text available
Understanding the spatial variability in plant litter processes is essential for accurate comprehension of biogeochemical cycles and ecosystem function. We assessed spatial patterns in litter processes from local to regional scales, at sites throughout the wet tropical rain forests of northern Australia. We aimed to determine the controls (e.g., cl...
Article
Full-text available
With the impending threat of climate change, greater understanding of patterns of species distributions and richness and the environmental factors driving them are required for effective conservation efforts. Species distribution models enable us to not only estimate geographic extents of species and subsequent patterns of species richness, but als...
Chapter
Global climate change is expected to cause major loss of biodiversity in the next century in both terrestrial and marine systems. Climate change impacts, including warming and extreme weather events, on life history, physiology, ecology and community and ecosystem interactions will increase the extinction risks for a variety of taxonomic groups.
Article
Extreme weather events, such as unusually hot or dry conditions, can cause death by exceeding physiological limits, and so cause loss of population. Survival will depend on whether or not susceptible organisms can find refuges that buffer extreme conditions. Microhabitats offer different microclimates to those found within the wider ecosystem, but...
Article
Full-text available
Biodiversity is spatially organized by climatic gradients across elevation and latitude. But do other gradients exist that might drive biogeographic patterns? Here, we show that rainforest's vertical strata provide climatic gradients much steeper than those offered by elevation and latitude, and biodiversity of arboreal species is organized along t...
Article
Correlative species distribution models (SDMs) combined with spatial layers of climate and species' localities represent a frequently utilized and rapid method for generating spatial estimates of species distributions. However, an SDM is only as accurate as the inputs upon which it is based. Current best-practice climate layers commonly utilized in...
Article
Full-text available
Species may circumvent the impacts of climate warming if the habitats they use reduce ambient temperature. In this study, we identified which frog species from a tropical montane rain forest in the Philippines may be vulnerable to climate warming. To do so, we selected five anuran species that utilize four breeding habitats and identified the sensi...
Article
Full-text available
Among birds, tropical montane species are likely to be among the most vulnerable to climate change, yet little is known about how climate drives their distributions, nor how to predict their likely responses to temperature increases. Correlative models of species' environmental niches have been widely used to predict changes in distribution, but di...
Data
Full-text available
Example fitted Gaussian curves. Gaussian curves (dashed lines) are shown fitted to the elevational density profiles for the remaining species examined for elevational difference in their estimated density optima between southern AWT (filled circles) and northern AWT (unfilled circles). Data are the estimated densities calculated with Distance analy...
Data
AIC scores for competing models in HOF [30] analysis. Shown are competing models in a hierarchical Huissman-Olff-Frescoe [30] model selection analysis for elevational density responses across the 88 Australian Wet Tropics rainforest bird species (those with sufficient sampling in this study). Models were selected using the approach implemented in t...
Data
Full-text available
Results of the Huisman-Olff-Frescoe (HOF) hierarchical model fitting process. Models are shown for rainforest bird density responses across the temperature gradient in the study region. Models tested were flat (light blue), plateau (green), monotonic (dark blue), unimodal (Gaussian) (red) and skewed (black). AIC values (upper right of each plot) we...