Showing papers by "Stephen E. Williams published in 2020"
TL;DR: In this paper, point location records for 226 anonymised species from six regions of the world, with accompanying predictor variables in raster (grid) and point formats, are published as a benchmark for modeling approaches and for testing new ways to evaluate the accuracy of SDMs.
Abstract: 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 surveys (e.g. opportunistic records). This need motivated a large-scale, collaborative effort, published in 2006, that aimed to create objective comparisons of algorithm performance. As a benchmark, and to facilitate future comparisons of approaches, here we publish that dataset: point location records for 226 anonymised species from six regions of the world, with accompanying predictor variables in raster (grid) and point formats. A particularly interesting characteristic of this dataset is that independent presence-absence survey data are available for evaluation alongside the presence-only species occurrence data intended for modeling. The dataset is available on Open Science Framework and as an R package and can be used as a benchmark for modeling approaches and for testing new ways to evaluate the accuracy of SDMs.
29 citations
TL;DR: This work synthesizes the National Adaptation Research Plans for marine, terrestrial and freshwater ecosystems and suggests 18 priority research topics based on their significance, urgency, technical and economic feasibility, existing knowledge gaps and potential for cobenefits across multiple sectors.
Abstract: 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 that addresses stakeholder-relevant knowledge gaps will accelerate effective uptake into adaptation policy and management action. After a decade of climate change adaptation research within the Australian National Climate Change Adaptation Research Facility, we synthesize the National Adaptation Research Plans for marine, terrestrial and freshwater ecosystems. We identify the key, globally relevant priorities for ongoing research relevant to informing adaptation policy and environmental management aimed at maximizing the resilience of natural ecosystems to climate change. Informed by both global literature and an extensive stakeholder consultation across all ecosystems, sectors and regions in Australia, involving thousands of participants, we suggest 18 priority research topics based on their significance, urgency, technical and economic feasibility, existing knowledge gaps and potential for cobenefits across multiple sectors. These research priorities provide a unified guide for policymakers, funding organizations and researchers to strategically direct resources, maximize stakeholder uptake of resulting knowledge and minimize the impacts of climate change on natural ecosystems. Given the pace of climate change, it is imperative that we inform and accelerate adaptation progress in all regions around the world.
17 citations
TL;DR: In this article, the relative influence of current environmental conditions (net primary productivity, NPP) versus historic environmental stability over the Last Glacial Maximum on niche filling patterns of vertebrates (mammals, birds, amphibians and reptiles) in the Australian Wet Tropics (AWTs).
Abstract: Aim: 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 environmental stability over the Last Glacial Maximum on niche filling patterns of vertebrates (mammals, birds, amphibians and reptiles) in the Australian Wet Tropics (AWTs). Location: Australian Wet Tropics. Taxon: Vertebrates (mammals, birds, amphibians and reptiles). Methods: We measured patterns of niche filling (niche packing vs. niche expansion) as the standardized departure of observed functional diversity (FD) from its null expectation. We fitted spatial models for vertebrates, and for each constituent class (mammals, birds, amphibians and reptiles) separately, to evaluate the relative effects of NPP and environmental stability on species richness and niche filling patterns. Results: Historical environmental stability had a greater effect than NPP on species richness and niche filling patterns. However, the directionality of this effect depended on phylogenetic scale, with vertebrates exhibiting niche packing while each constituent class (except reptiles) exhibited niche expansion with increasing environmental stability. Main Conclusion: Intra-class competition presumably leads to niche differentiation and expansion, whereas the overlap of functional traits among species from different classes leads to niche packing. That environmental stability over millennia is associated with an expanding niche space across multiple vertebrate classes suggests that the accumulation of FD within communities requires long recovery times.
6 citations
TL;DR: 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 as discussed by the authors.
Abstract: 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 distribution of Anonychomyrma in the Australian Wet Tropics bioregion, where only two of the many putative species are described. We hypothesise that the genus in tropical Australia retains a preference for cool wet rainforests reminiscent of the Gondwanan forests that once dominated Australia, but now only exist in upland habitats of the Wet Tropics. Our study was based on extensive recent surveys across five subregions and along elevation and vertical (arboreal) gradients. We integrated genetic (CO1) data with morphology to recognise 22 species among our samples, 20 of which appeared to be undescribed. As predicted, diversity and endemism were concentrated in uplands above 900 m a.s.l. Distribution modelling of the nine commonest species identified maximum temperature of the warmest month, rainfall seasonality, and rainfall of the wettest month as correlates of distributional patterns across subregions. Our study supported the notion that Anonychomyrma radiated from a southern temperate origin into the tropical zone, with a preference for areas of montane rainforest that were stably cool and wet over the late quaternary.
6 citations