ORCID Profile
0000-0002-0669-1418
Current Organisation
University of Adelaide
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Publisher: Wiley
Date: 28-08-2022
DOI: 10.1111/GCB.16375
Abstract: Processes leading to range contractions and population declines of Arctic megafauna during the late Pleistocene and early Holocene are uncertain, with intense debate on the roles of human hunting, climatic change, and their synergy. Obstacles to a resolution have included an overreliance on correlative rather than process‐explicit approaches for inferring drivers of distributional and demographic change. Here, we disentangle the ecological mechanisms and threats that were integral in the decline and extinction of the muskox ( Ovibos moschatus ) in Eurasia and in its expansion in North America using process‐explicit macroecological models. The approach integrates modern and fossil occurrence records, ancient DNA, spatiotemporal reconstructions of past climatic change, species‐specific population ecology, and the growth and spread of anatomically modern humans. We show that accurately reconstructing inferences of past demographic changes for muskox over the last 21,000 years require high dispersal abilities, large maximum densities, and a small Allee effect. Analyses of validated process‐explicit projections indicate that climatic change was the primary driver of muskox distribution shifts and demographic changes across its previously extensive (circumpolar) range, with populations responding negatively to rapid warming events. Regional analyses show that the range collapse and extinction of the muskox in Europe (~13,000 years ago) was likely caused by humans operating in synergy with climatic warming. In Canada and Greenland, climatic change and human activities probably combined to drive recent population sizes. The impact of past climatic change on the range and extinction dynamics of muskox during the Pleistocene–Holocene transition signals a vulnerability of this species to future increased warming. By better establishing the ecological processes that shaped the distribution of the muskox through space and time, we show that process‐explicit macroecological models have important applications for the future conservation and management of this iconic species in a warming Arctic.
Publisher: Springer Science and Business Media LLC
Date: 03-02-2020
Publisher: Public Library of Science (PLoS)
Date: 14-11-2014
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-08-2020
Abstract: The late Quaternary paleorecord, within the past ∼130,000 years, can help to inform present-day management of the Earth's ecosystems and biota under climate change. Fordham et al. review when and where rapid climate transitions can be found in the paleoclimate record. They show how such events in Earth's history can shape our understanding of the consequences of future global warming, including rates of bio ersity loss, changes in ecosystem structure and function, and degradation in the goods and services that these ecosystems provide to humanity. They also highlight how recent developments at the intersection of paleoecology, paleoclimatology, and macroecology can provide opportunities to anticipate and manage the responses of species and ecosystems to changing climates in the Anthropocene. Science , this issue p. eabc5654
Publisher: Elsevier BV
Date: 11-2022
Publisher: Wiley
Date: 28-09-2021
Abstract: Spatially explicit population models (SEPMs) can simulate spatiotemporal changes in species' range dynamics in response to variation in climatic and environmental conditions, and anthropogenic activities. When combined with pattern‐oriented modelling methods, ecological processes and drivers of range shifts and extinctions can be identified, and plausible chains of causality revealed. The open‐source multi‐platform R package poems provides functionality for simulating and validating projections of species' range dynamics using stochastic, lattice‐based population models. Built‐in modules allow parameter uncertainty to propagate through to model simulations, with their effects on species' range dynamics evaluated using Approximate Bayesian Computation. These validation procedures identify models with the structural complexity and parameterisation needed to simulate the effects of past changes in climate, environment and human activities on species' range shifts and extinction risk. We illustrate the features and versatility of poems by simulating the historical decline and extinction of the Thylacine Thylacinus cynocephalus , an icon of recent extinctions in Australia. We show that poems can reveal likely ecological pathways to extinction using pattern‐oriented methods, providing validated projections of the range collapse and population decline of threatened species. By providing flexible and extendable modules for building and validating SEPMs of species' range dynamics, poems allows the effects of past and future threats on species' populations to be quantified using well‐parameterised, structurally realistic models, with important generative mechanisms. Since poems can directly unravel ecological processes of species responses to global change, and strengthen predictions of range shifts and extinction risk—within a flexible, R‐based environment—we anticipate that poems will be of significant value to ecologists, conservation managers and biogeographers.
Publisher: Wiley
Date: 14-06-2014
DOI: 10.1111/GCB.12634
Publisher: Wiley
Date: 19-10-2022
DOI: 10.1111/GEB.13601
Abstract: To determine the ecological processes and drivers of range collapse, population decline and eventual extinction of the steppe bison in Eurasia. Siberia. Pleistocene and Holocene. Steppe bison ( Bison priscus ). We configured 110,000 spatially explicit population models (SEPMs) of climate–human–steppe bison interactions in Siberia, which we ran at generational time steps from 50,000 years before present. We used pattern‐oriented modelling (POM) and fossil‐based inferences of distribution and demographic change of steppe bison to identify which SEPMs adequately simulated important interactions between ecological processes and biological threats. These “best models” were then used to disentangle the mechanisms that were integral in the population decline and later extinction of the steppe bison in its last stronghold in Eurasia. Our continuous reconstructions of the range and extinction dynamics of steppe bison were able to reconcile inferences of spatio‐temporal occurrence and the timing and location of extinction in Siberia based on hundreds of radiocarbon‐dated steppe bison fossils. We showed that simulating the ecological pathway to extinction for steppe bison in Siberia in the early Holocene required very specific ecological niche constraints, demographic processes and a constrained synergy of climate and human hunting dynamics during the Pleistocene–Holocene transition. Ecological processes and drivers that caused ancient population declines of species can be reconstructed at high spatio‐temporal resolutions using SEPMs and POM. Using this approach, we found that climatic change and hunting by humans are likely to have interacted with key ecological processes to cause the extinction of the steppe bison in its last refuge in Eurasia.
Publisher: Cold Spring Harbor Laboratory
Date: 18-02-2021
DOI: 10.1101/2021.02.17.431706
Abstract: Pathways to extinction start long before the death of the last in idual. However, causes of early-stage population declines and the susceptibility of small residual populations to extirpation are typically studied in isolation. Using validated process-explicit models, we disentangle the ecological mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth. We show that reconciling ancient DNA data on woolly mammoth population decline with fossil evidence of location and timing of extinction requires process-explicit models with specific demographic and niche constraints, and a constrained synergy of climatic change and human impacts. Validated models needed humans to hasten climate-driven population declines by many millennia, and to allow woolly mammoths to persist in mainland Arctic refugia until the mid-Holocene. Our results show that the role of humans in the extinction dynamics of woolly mammoth began well before the Holocene, exerting lasting effects on the spatial pattern and timing of its range-wide extinction.
Publisher: Wiley
Date: 05-11-2021
DOI: 10.1111/ELE.13911
Abstract: Pathways to extinction start long before the death of the last in idual. However, causes of early stage population declines and the susceptibility of small residual populations to extirpation are typically studied in isolation. Using validated process‐explicit models, we disentangle the ecological mechanisms and threats that were integral in the initial decline and later extinction of the woolly mammoth. We show that reconciling ancient DNA data on woolly mammoth population decline with fossil evidence of location and timing of extinction requires process‐explicit models with specific demographic and niche constraints, and a constrained synergy of climatic change and human impacts. Validated models needed humans to hasten climate‐driven population declines by many millennia, and to allow woolly mammoths to persist in mainland Arctic refugia until the mid‐Holocene. Our results show that the role of humans in the extinction dynamics of woolly mammoth began well before the Holocene, exerting lasting effects on the spatial pattern and timing of its range‐wide extinction.
Publisher: Springer Science and Business Media LLC
Date: 12-10-2020
DOI: 10.1038/S41597-020-00663-3
Abstract: Paleoclimatic data are used in eco-evolutionary models to improve knowledge of biogeographical processes that drive patterns of bio ersity through time, opening windows into past climate–bio ersity dynamics. Applying these models to harmonised simulations of past and future climatic change can strengthen forecasts of bio ersity change. StableClim provides continuous estimates of climate stability from 21,000 years ago to 2100 C.E. for ocean and terrestrial realms at spatial scales that include biogeographic regions and climate zones. Climate stability is quantified using annual trends and variabilities in air temperature and precipitation, and associated signal-to-noise ratios. Thresholds of natural variability in trends in regional- and global-mean temperature allow periods in Earth’s history when climatic conditions were warming and cooling rapidly (or slowly) to be identified and climate stability to be estimated locally (grid-cell) during these periods of accelerated change. Model simulations are validated against independent paleoclimate and observational data. Projections of climatic stability, accessed through StableClim , will improve understanding of the roles of climate in shaping past, present-day and future patterns of bio ersity.
Publisher: Wiley
Date: 15-09-2020
DOI: 10.1002/ECE3.6705
Publisher: Elsevier BV
Date: 05-2019
DOI: 10.1016/J.CUB.2019.04.001
Abstract: The stability of regional climates on millennial timescales is theorised to be a primary determinant of nearby ersification [1-5]. Using simulated patterns of past temperature change at monthly timescales [6], we show that the locations of climatically stable regions are likely to have varied considerably across and within millennia during glacial-interglacial cycles of the Late Quaternary. This result has important implications for the role of regional climate stability in theories of speciation, because long-term climate refugia are typically presumed to be 'cradles' of ersity (areas of high speciation) only if they remain stable across Milankovitch climate oscillations [1-5], which operate on multi-millennial time scales [7].
Publisher: Springer Science and Business Media LLC
Date: 22-05-2020
DOI: 10.1038/S41467-020-16449-5
Abstract: Knowledge of global patterns of bio ersity, ranging from intraspecific genetic ersity (GD) to taxonomic and phylogenetic ersity, is essential for identifying and conserving the processes that shape the distribution of life. Yet, global patterns of GD and its drivers remain elusive. Here we assess existing bio ersity theories to explain and predict the global distribution of GD in terrestrial mammal assemblages. We find a strong positive covariation between GD and interspecific ersity, with evolutionary time, reflected in phylogenetic ersity, being the best predictor of GD. Moreover, we reveal the negative effect of past rapid climate change and the positive effect of inter-annual precipitation variability in shaping GD. Our models, explaining almost half of the variation in GD globally, uncover the importance of deep evolutionary history and past climate stability in accumulating and maintaining intraspecific ersity, and constitute a crucial step towards reducing the Wallacean shortfall for an important dimension of bio ersity.
Publisher: Wiley
Date: 20-05-2019
DOI: 10.1002/ECY.2750
Abstract: With ongoing introductions into Australia since the 1700s, the European rabbit (Oryctolagus cuniculus) has become one of the most widely distributed and abundant vertebrate pests, adversely impacting Australia's bio ersity and agroeconomy. To understand the population and range dynamics of the species and its impacts better, occurrence and abundance data have been collected by researchers and citizens from sites covering a broad spectrum of climatic and environmental conditions in Australia. The lack of a common and accessible repository for these data has, however, limited their use in determining important spatiotemporal drivers of the structure and dynamics of the geographical range of rabbits in Australia. To meet this need, we created the Australian National Rabbit Database, which combines more than 50 yr of historical and contemporary survey data collected from throughout the range of the species in Australia. The survey data, obtained from a suite of complementary monitoring methods, were combined with high-resolution weather, climate, and environmental information, and an assessment of data quality. The database provides records of rabbit occurrence (689,265 records) and abundance (51,241 records, >120 distinct sites) suitable for identifying the spatiotemporal drivers of the rabbit's distribution and for determining spatial patterns of variation in its key life-history traits, including maximum rates of population growth. Because all data are georeferenced and date st ed, they can be coupled with information from other databases and spatial layers to explore the potential effects of rabbit occurrence and abundance on Australia's native wildlife and agricultural production. The Australian National Rabbit Database is an important tool for understanding and managing the European rabbit in its invasive range and its effects on native bio ersity and agricultural production. It also provides a valuable resource for addressing questions related to the biology, success, and impacts of invasive species more generally. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper.
Publisher: Cold Spring Harbor Laboratory
Date: 08-10-2022
DOI: 10.1101/2022.10.06.511126
Abstract: The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea-ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. By integrating genomics, isotopic analysis, morphometrics, and ecological modelling, we investigate how Holocene environmental changes affected the evolutionary ecology of polar bears around Greenland. We show that throughout the last ∼11,000 years, Greenlandic polar bears have been heavily influenced by changes in sea-surface temperature (SST) and sea-ice cover. Most notable are major reductions in effective population size at the beginning of the Holocene and during the Holocene Thermal Maximum ∼6 kya, which coincide with increases in annual mean SST, reduction in sea-ice covers, declines in suitable habitat, and shifts in suitable habitat northwards. Furthermore, we show how in iduals s led from west and east Greenland are genetically, morphologically, and ecologically distinct. We find bears s led in west Greenland to be larger, more genetically erse and have diets dominated by ringed seals, whereas bears from east Greenland are smaller and less erse with more varied diets, putatively driven by regional biotic differences. Taken together, we provide novel insights into the vulnerability of polar bears to environmental change, and how the Arctic marine ecosystem plays a vital role in shaping the evolutionary and ecological trajectories of its inhabitants. Multivariate investigations of the environment’s role in the evolutionary ecology of Greenlandic polar bears.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/AM16018
Abstract: Cannibalism in predators has been reported for a range of species throughout the world, including observations of dingoes (Canis familiaris) eating dingoes in Australia. Here, we report on camera trap observations of dingoes feeding on the carcasses of dingoes and showing aggressive behaviours towards live-trapped conspecifics. At this site, cannibalism and conspecific aggression by dingoes was not caused by food shortages, but was more likely a result of high dingo density in a focal area. We present the first camera trap image observations of dingoes eating dingoes and describe aggressive encounters between live animals.
Publisher: Research Square Platform LLC
Date: 12-09-2023
Publisher: California Digital Library (CDL)
Date: 27-03-2019
Publisher: Wiley
Date: 08-2012
Publisher: Springer Science and Business Media LLC
Date: 17-06-2015
Publisher: Wiley
Date: 14-07-2022
DOI: 10.1111/GCB.16328
Abstract: The vulnerability of marine bio ersity to accelerated rates of climatic change is poorly understood. By developing a new method for identifying extreme oceanic warming events during Earth's most recent deglaciation, and comparing these to 21st century projections, we show that future rates of ocean warming will disproportionately affect the most speciose marine communities, potentially threatening bio ersity in more than 70% of current-day global hotspots of marine species richness. The persistence of these richest areas of marine bio ersity will require many species to move well beyond the biogeographic realm where they are endemic, at rates of redistribution not previously seen. Our approach for quantifying exposure of bio ersity to past and future rates of oceanic warming provides new context and scalable information for deriving and strengthening conservation actions to safeguard marine bio ersity under climate change.
Publisher: Wiley
Date: 30-10-2017
DOI: 10.1111/GCB.13932
Abstract: The current distribution of species, environmental conditions and their interactions represent only one snapshot of a planet that is continuously changing, in part due to human influences. To distinguish human impacts from natural factors, the magnitude and pace of climate shifts, since the Last Glacial Maximum, are often used to determine whether patterns of ersity today are artefacts of past climate change. In the absence of high-temporal resolution palaeoclimate reconstructions, this is generally done by assuming that past climate change occurred at a linear pace between widely spaced (usually, ≥1,000 years) climate snapshots. We show here that this is a flawed assumption because regional climates have changed significantly across decades and centuries during glacial-interglacial cycles, likely causing rapid regional replacement of biota. We demonstrate how recent atmosphere-ocean general circulation model (AOGCM) simulations of the climate of the past 21,000 years can provide credible estimates of the details of climate change on decadal to centennial timescales, showing that these details differ radically from what might be inferred from longer timescale information. High-temporal resolution information can provide more meaningful estimates of the magnitude and pace of climate shifts, the location and timing of drivers of physiological stress, and the extent of novel climates. They also produce new opportunities to directly investigate whether short-term climate variability is more important in shaping bio ersity patterns rather than gradual changes in long-term climatic means. Together, these more accurate measures of past climate instability are likely to bring about a better understanding of the role of palaeoclimatic change and variability in shaping current macroecological patterns in many regions of the world.
Publisher: Wiley
Date: 06-05-2019
DOI: 10.1111/GCB.14625
Abstract: In the face of increasing cumulative effects from human and natural disturbances, sustaining coral reefs will require a deeper understanding of the drivers of coral resilience in space and time. Here we develop a high-resolution, spatially explicit model of coral dynamics on Australia's Great Barrier Reef (GBR). Our model accounts for biological, ecological and environmental processes, as well as spatial variation in water quality and the cumulative effects of coral diseases, bleaching, outbreaks of crown-of-thorns starfish (Acanthaster cf. solaris), and tropical cyclones. Our projections reconstruct coral cover trajectories between 1996 and 2017 over a total reef area of 14,780 km
Publisher: Springer Science and Business Media LLC
Date: 11-08-2011
Publisher: Wiley
Date: 09-03-2020
DOI: 10.1002/EAP.2083
Abstract: The European rabbit (Oryctolagus cuniculus) is a notorious economic and environmental pest species in its invasive range. To better understand the population and range dynamics of this species, 41 yr of abundance data have been collected from 116 unique sites across a broad range of climatic and environmental conditions in Australia. We analyzed this time series of abundance data to determine whether interannual variation in climatic conditions can be used to map historic, contemporary, and potential future fluctuations in rabbit abundance from regional to continental scales. We constructed a hierarchical Bayesian regression model of relative abundance that corrected for observation error and seasonal biases. The corrected abundances were regressed against environmental and disease variables in order to project high spatiotemporal resolution, continent-wide rabbit abundances. We show that rabbit abundance in Australia is highly variable in space and time, being driven primarily by internnual variation in temperature and precipitation in concert with the prevalence of a non-pathogenic virus. Moreover, we show that internnual variation in local spatial abundances can be mapped effectively at a continental scale using highly resolved spatiotemporal predictors, allowing "hot spots" of persistently high rabbit abundance to be identified. Importantly, cross-validated model performance was fair to excellent within and across distinct climate zones. Long-term monitoring data for invasive species can be used to map fine-scale spatiotemporal fluctuations in abundance patterns when accurately accounting for inherent s ling biases. Our analysis provides ecologists and pest managers with a clearer understanding of the determinants of rabbit abundance in Australia, offering an important new approach for predicting spatial abundance patterns of invasive species at the near-term temporal scales that are directly relevant to resource management.
Publisher: Wiley
Date: 20-11-2018
DOI: 10.1111/GCB.13935
Abstract: Criticism has been levelled at climate-change-induced forecasts of species range shifts that do not account explicitly for complex population dynamics. The relative importance of such dynamics under climate change is, however, undetermined because direct tests comparing the performance of demographic models vs. simpler ecological niche models are still lacking owing to difficulties in evaluating forecasts using real-world data. We provide the first comparison of the skill of coupled ecological-niche-population models and ecological niche models in predicting documented shifts in the ranges of 20 British breeding bird species across a 40-year period. Forecasts from models calibrated with data centred on 1970 were evaluated using data centred on 2010. We found that more complex coupled ecological-niche-population models (that account for dispersal and metapopulation dynamics) tend to have higher predictive accuracy in forecasting species range shifts than structurally simpler models that only account for variation in climate. However, these better forecasts are achieved only if ecological responses to climate change are simulated without static snapshots of historic land use, taken at a single point in time. In contrast, including both static land use and dynamic climate variables in simpler ecological niche models improve forecasts of observed range shifts. Despite being less skilful at predicting range changes at the grid-cell level, ecological niche models do as well, or better, than more complex models at predicting the magnitude of relative change in range size. Therefore, ecological niche models can provide a reasonable first approximation of the magnitude of species' potential range shifts, especially when more detailed data are lacking on dispersal dynamics, demographic processes underpinning population performance, and change in land cover.
Publisher: Cold Spring Harbor Laboratory
Date: 10-02-2023
DOI: 10.1101/2023.02.09.526923
Abstract: The drivers and dynamics of initial human migrations across in idual islands and archipelagos are poorly understood, affecting assessments of human-modification of island bio ersity. Here, we describe and test a process-explicit approach for reconstructing human arrival and expansion on islands, which combines archaeological and climate records with high-resolution spatial population models. Using Polynesian colonisation of New Zealand as an ex le, we show that our new method can generate information crucial for assessing how humans affected bio ersity on islands. The transition of islands from prehuman to human dominated ecosystems has typically been assessed by comparing bio ersity before and after time of first arrival, without considering the potential importance of the spatiotemporal dynamics of the human expansion event. Our new approach, which uses pattern-oriented modelling methods to combine inferences of human colonisation dynamics from dated archaeological material with spatially explicit population models, produces validated reconstructions of the pattern and pace of human migration across islands at high spatiotemporal resolutions. From these reconstructions, demographic and environmental drivers of human colonization can be identified, and the role that people had on bio ersity established. Using this technique, we show that closely reconciling inferences of Polynesian colonisation of New Zealand requires there to have been a single founding population of approximately 500 people, arriving between 1233 and 1257 AD, settling multiple areas, and expanding quickly over both North and South islands. The resultant maps of Māori colonisation dynamics provide new opportunities to better determine how human activities transformed bio ersity of New Zealand in space and time. Process-explicit models can reconstruct human migration across large islands, producing validated, high resolution spatiotemporal projections of human occupancy and abundance that account for dispersal and population dynamics. This modelling framework should prove effective across any islands and archipelagos where climate and archaeological records are available.
Publisher: Elsevier BV
Date: 09-2019
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/WR18129
Abstract: Context Wildlife and pest managers and stakeholders should constantly aim to improve animal-welfare outcomes when foot-hold trapping pest animals. To minimise stress and trauma to trapped animals, traps should be checked at least once every 24h, normally as soon after sunrise as possible. If distance, time, environmental or geographical constraints prevent this, toxins such as strychnine can be fitted to trap jaws to induce euthanasia. However, strychnine is considered to have undesirable animal-welfare outcomes because animals are conscious while clinical signs of intoxication are present. A toxin considered more humane, para-aminopropiophenone (PAPP), is available to induce euthanasia in trapped animals but is untested for presentation and efficacy. Aim We tested the efficacy of two types of lethal trap device (LTD’s), each using a paste formulation of PAPP as the active toxin to replace the use of strychnine on foot-hold jaw traps. Methods Elastomer LTDs and PAPP-cloths were fitted to jaw traps set to capture wild dogs (Canis familiaris). Camera-trap data was used to record animal behaviours after capture and to determine the efficacy of both modalities. Key results Every trapped wild dog (n=117) gnawed at the elastomer LTD’s or PAPP-cloth attached to the trap jaws that restrained them one dog failed to liberate the toxin. From the dogs caught in the main trial (n=56), a mortality rate of 84% and 87% was reported respectively. The mean time from trap-to-death for elastomer LTDs was 64min and 68min for PAPP-cloths. Conclusions Elastomer LTDs and PAPP cloths combined caused the mortality of 85% of captured dogs. This efficacy could be improved by adopting the recommendations discussed in the present study for deploying PAPP-based LTDs during trap deployment. Implications PAPP-based LTDs offer an alternative option to the use of strychnine and improve the welfare outcomes for trapped predators, especially where traps are not checked within the recommended 24-h period.
No related grants have been discovered for Stuart Brown.