ORCID Profile
0000-0001-7935-6111
Current Organisations
Macquarie University
,
University of Oxford
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Frontiers Media SA
Date: 27-11-2020
DOI: 10.3389/FPSYG.2020.604617
Abstract: Researchers have long debated the extent to which an in idual’s skin tone influences their perceived race. Brooks and Gwinn (2010) demonstrated that the race of surrounding faces can affect the perceived skin tone of a central target face without changing perceived racial typicality, suggesting that skin lightness makes a small contribution to judgments of race compared to morphological cues (the configuration and shape of the facial features). However, the lack of a consistent light source may have undermined the reliability of skin tone cues, encouraging observers to rely disproportionately on morphological cues instead. The current study addresses this concern by using 3D models of male faces with typically Black African or White European appearances that are illuminated by the same light source. Observers perceived target faces surrounded by White faces to have darker skin than those surrounded by Black faces, particularly for faces of intermediate lightness. However, when asked to judge racial typicality, a small assimilation effect was evident, with target faces perceived as more stereotypically White when surrounded by White than when surrounded by Black faces at intermediate levels of typicality. This evidence of assimilation effects for perceived racial typicality despite concurrent contrast effects on perceived skin lightness supports the previous conclusion that perceived skin lightness has little influence on judgments of racial typicality for racially ambiguous faces, even when lighting is consistent.
Publisher: Frontiers Media SA
Date: 22-08-2016
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-05-2017
Abstract: Biotic interactions underlie ecosystem structure and function, but predicting interaction outcomes is difficult. We tested the hypothesis that biotic interaction strength increases toward the equator, using a global experiment with model caterpillars to measure predation risk. Across an 11,660-kilometer latitudinal gradient spanning six continents, we found increasing predation toward the equator, with a parallel pattern of increasing predation toward lower elevations. Patterns across both latitude and elevation were driven by arthropod predators, with no systematic trend in attack rates by birds or mammals. These matching gradients at global and regional scales suggest consistent drivers of biotic interaction strength, a finding that needs to be integrated into general theories of herbivory, community organization, and life-history evolution.
Publisher: Wiley
Date: 26-11-2020
DOI: 10.1111/ECOG.05390
Abstract: The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5°C in mean temperature. Our cost‐effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5–9 host and 5–11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely‐interacting species that are erse enough to be representative, yet still amenable to field and laboratory experiments.
Publisher: Public Library of Science (PLoS)
Date: 31-01-2018
Publisher: Public Library of Science (PLoS)
Date: 15-02-2013
Publisher: Cold Spring Harbor Laboratory
Date: 07-02-2020
DOI: 10.1101/2020.02.05.935858
Abstract: Interspecific competition, a dominant process structuring ecological communities, acts on species’ phenotypic differences. Species with similar traits should compete intensely (trait-similarity), while those with traits that confer competitive ability should outcompete others (trait-hierarchy). Either or both of these mechanisms may drive competitive exclusion within a community, but their relative importance and interacting effects are rarely studied. We show empirically that spatial associations (pairwise co-occurrences) between an invasive ant Solenopsis invicta and 28 other ant species across a relatively homogenous landscape are explained largely by an interaction of trait-similarity and trait-hierarchy in one morphological trait. We find that increasing trait-hierarchy leads to more negative associations however these effects are counteracted when species are sufficiently dissimilar (by 37-95%) in their trait ranges. We also show that a model of species co-occurrences integrating trait-similarity and trait-hierarchy consolidates predictions of different theoretical assembly rules. This highlights the explanatory potential of the trait-based co-occurrence approach.
Publisher: Wiley
Date: 15-11-2020
Abstract: There is growing interest in the ecological value of set‐aside habitats around rivers in tropical agriculture. These riparian buffers typically comprise forest or other non‐production habitat, and are established to maintain water quality and hydrological processes, while also supporting bio ersity, ecosystem function and landscape connectivity. We investigated the capacity for riparian buffers to act as microclimatic refugia by combining field‐based measurements of temperature, humidity and dung beetle communities with remotely sensed data from LiDAR across an oil palm dominated landscape in Borneo. Riparian buffers offer a cool and humid habitat relative to surrounding oil palm plantations, with wider buffers characterised by conditions comparable to riparian sites in continuous logged forest. High vegetation quality and topographic sheltering were strongly associated with cooler and more humid microclimates in riparian habitats across the landscape. Variance in beetle ersity was also predicted by both proximity‐to‐edge and microclimatic conditions within the buffer, suggesting that narrow buffers lify the negative impacts that high temperatures have on bio ersity. Synthesis and applications . Widely legislated riparian buffer widths of 20–30 m each side of a river may provide drier and less humid microclimatic conditions than continuous forest. Adopting wider buffers and maintaining high vegetation quality will ensure set‐asides established for hydrological reasons bring co‐benefits for terrestrial bio ersity, both now, and in the face of anthropogenic climate change.
Publisher: Cold Spring Harbor Laboratory
Date: 26-01-2021
DOI: 10.1101/2021.01.25.428088
Abstract: Understanding how species’ phenotypic differences affect competition is key to explaining community assembly and predicting bio ersity responses. Many studies overlook the variable effects that species’ trait differences can have on the direction of competitive exclusion, which reverses depending on the specific mechanism at play. We performed a comprehensive trait-based study of an ant invasion integrating morphological, dietary, physiological and behavioral analyses. We found that trait differences between invasive and resident species were not only associated with niche differences which promoted the coexistence of dissimilar species, but also competitive ability differences which acted in the opposite fashion. Furthermore, competition along separate trait axes led to complex and contrasting patterns in the invaded assemblages, where species were at once similar (clustered) in some traits but also dissimilar (overdispersed) in others. Our results reveal that different aspects of phenotype may distinctly modulate the effect of competition in structuring ecological communities and functional ersity.
Publisher: Wiley
Date: 13-12-2018
DOI: 10.1111/BRV.12488
Publisher: Cold Spring Harbor Laboratory
Date: 20-08-2018
DOI: 10.1101/395624
Abstract: Competition within and between species can have large effects on fitness and may therefore drive local adaptation. However, these effects are rarely tested systematically, or considered when predicting species’ responses to environmental change. We used a field transplant experiment to test the effects of intra and interspecific competition on fitness across the ecological niches of two rainforest Drosophila species that replace each other along an elevation gradient. For the species with the broader elevational range, we also tested for adaptation to the local abiotic and biotic environment. In both species, intraspecific competition reduced productivity more than interspecific competition at the centre of its elevational range, while interspecific competition had a stronger effect at the range edge, where the competing species is more abundant. Local adaptation was detected in the centre of the range of the more widespread species, but only in the presence of intraspecific competition. This study is the first to demonstrate that fitness effects of inter-specific competition increase at ecological margins, while intra-specific competition has more pervasive effects at range centres. This is a key assumption of “tangled bank” models of community evolution and has important implications for predicting the resilience of ecological networks to global change.
Publisher: Frontiers Media SA
Date: 24-09-2014
Publisher: Wiley
Date: 27-11-2020
DOI: 10.1111/MEC.15724
Abstract: The application of metabarcoding to environmental and invertebrate‐derived DNA (eDNA and iDNA) is a new and increasingly applied method for monitoring bio ersity across a erse range of habitats. This approach is particularly promising for s ling in the bio erse humid tropics, where rapid land‐use change for agriculture means there is a growing need to understand the conservation value of the remaining mosaic and degraded landscapes. Here we use iDNA from blood‐feeding leeches ( Haemadipsa picta ) to assess differences in mammalian ersity across a gradient of forest degradation in Sabah, Malaysian Borneo. We screened 557 in idual leeches for mammal DNA by targeting fragments of the 16S rRNA gene and detected 14 mammalian genera. We recorded lower mammal ersity in the most heavily degraded forest compared to higher quality twice logged forest. Although the accumulation curves of ersity estimates were comparable across these habitat types, ersity was higher in twice logged forest, with more taxa of conservation concern. In addition, our analysis revealed differences between the community recorded in the heavily logged forest and that of the twice logged forest. By revealing differences in mammal ersity across a human‐modified tropical landscape, our study demonstrates the value of iDNA as a noninvasive biomonitoring approach in conservation assessments.
Publisher: SAGE Publications
Date: 27-10-2017
Abstract: Although body size and shape misperception (BSSM) is a common feature of anorexia nervosa, bulimia nervosa and muscle dysmorphia, little is known about its underlying neural mechanisms. Recently, a new approach has emerged, based on the long-established non-invasive technique of perceptual adaptation, which allows for inferences about the structure of the neural apparatus responsible for alterations in visual appearance. Here, we describe several recent experimental ex les of BSSM, wherein exposure to “extreme” body stimuli causes visual aftereffects of biased perception. The implications of these studies for our understanding of the neural and cognitive representation of human bodies, along with their implications for clinical practice are discussed.
Publisher: MDPI AG
Date: 07-2023
DOI: 10.3390/RS15133374
Abstract: In intelligent traffic control systems, the features extracted by loop detectors are insufficient to accurately impute missing data. Most of the existing imputation methods use only these extracted features, which leads to the construction of data models that cannot fulfill the required accuracy. This deficiency is the main motivation to propose an enrichment imputation method for loop detectors namely EIM-LD, in which the imputation accuracy is increased for different missing patterns and ratios by introducing a data enrichment technique using statistical multi-class labeling. It first enriches the clean data by adding a statistical multi-class label, including C1…Cn classes. Then, the class of s les in the missed-volume data is labeled using the best data model constructed from the labeled clean data by five different classifiers. Experts of the traffic control department in Isfahan city determined classes of the statistical multi-class label for n = 5 (class labels), and we also developed subclass labels (n = 20) since the number of s les in the subclass labels was sufficient. Next, the enriched data are ided into n datasets, each of them is imputed independently using various imputation methods, and their results are finally merged. To evaluate the impact of using the proposed method, the original data, including missing volumes, are first imputed without our enrichment method. Then, the proposed method’s accuracy is evaluated by considering two class labels and subclass labels. The experimental and statistical results prove that the proposed EIM-LD method can enrich the real data collected by loop detectors, by which the comparative imputation methods construct a more accurate data model. In addition, using subclass labels further enhances the imputation method’s accuracy.
Publisher: Wiley
Date: 27-12-2019
DOI: 10.1111/BJOP.12439
Abstract: Body image disturbance - a cause of distress amongst the general population and those diagnosed with various disorders - is often attributed to the media's unrealistic depiction of ideal bodies. These ideals are strongly gendered, leading to pronounced fat concern amongst females, and a male preoccupation with muscularity. Recent research suggests that visual aftereffects may be fundamental to the misperception of body fat and muscle mass - the perceptual component of body image disturbance. This study sought to establish the influence of gender on these body aftereffects. Male and female observers were randomly assigned to one of four adaptation conditions (low-fat, high-fat, low-muscle, and high-muscle bodies) and were asked to adjust the apparent fat and muscle levels of male and female bodies to make them appear as 'normal' as possible both before adaptation and after adaptation. While neither the gender of observers nor of body stimuli had a direct effect, aftereffect magnitude was significantly larger when observers viewed own-gender (compared with other-gender) stimuli. This effect, which may be due to attentional factors, could have implications for the development of body image disturbance, given the preponderance of idealized own-gender bodies in media marketed to male and female consumers.
Publisher: Wiley
Date: 09-05-2022
Abstract: Temperature change is an often‐assumed, but rarely tested, mechanism by which sensitive species may decline in forest landscapes following habitat degradation, fragmentation and destruction. Traits mediate how species respond to environmental change, with physiological, morphological and behavioural traits key to determining the response of ectotherms to temperature. We collected data on traits linked to thermal sensitivity (critical thermal maxima, body size, cuticle lightness and pilosity) for 46 dung beetle species ( Scarabaeinae ) in a forest–oil palm mosaic in Malaysian Borneo. By combining these data with a large‐scale community s ling c aign ( ,000 in iduals s led from traps) and an airborne Light Detection and Ranging‐derived thermal map, we investigated how traits mediate species‐ and community‐level responses to temperature. Using hierarchical models, we found that critical thermal maxima predicted how species respond to maximum temperatures. These results were mirrored in community‐level analyses alongside similar patterns in other thermal traits. Increased body size and decreased pilosity were associated with higher temperatures, while cuticle lightness showed a complex relationship with temperature across the disturbance gradient. Our findings highlight the potential mechanisms by whichforest specialists decline in human‐modified landscapes, resulting in changes to community patterns and processes. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: Frontiers Media SA
Date: 15-07-2016
Publisher: Springer Science and Business Media LLC
Date: 10-01-2017
DOI: 10.1038/SREP40392
Abstract: Although research addressing body size misperception has focused on socio-cognitive processes, such as internalization of the “ideal” images of bodies in the media, the perceptual basis of this phenomenon remains largely unknown. Further, most studies focus on body size per se even though this depends on both fat and muscle mass – variables that have very different relationships with health. We tested visual adaptation as a mechanism for inducing body fat and muscle mass misperception, and assessed whether these two dimensions of body space are processed independently. Observers manipulated the apparent fat and muscle mass of bodies to make them appear “normal” before and after inspecting images from one of four adaptation conditions (increased fat/decreased fat/increased muscle/decreased muscle). Exposure resulted in a shift in the point of subjective normality in the direction of the adapting images along the relevant (fat or muscle) axis, suggesting that the neural mechanisms involved in body fat and muscle perception are independent. This supports the viability of adaptation as a model of real-world body size misperception, and extends its applicability to clinical manifestations of body image disturbance that entail not only preoccupation with thinness (e.g., anorexia nervosa) but also with muscularity (e.g., muscle dysmorphia).
Publisher: Cold Spring Harbor Laboratory
Date: 18-04-2019
DOI: 10.1101/611749
Abstract: Invasive insects represent major threats to ecosystems worldwide. Yet their effects on the functional dimension of bio ersity, measured as the ersity and distribution of traits, are overlooked. Such measures often determine the resilience of ecological communities and the ecosystem processes they modulate. The fire ant Solenopsis invicta is a highly problematic invasive species occurring on five continents. Its impacts on the taxonomic ersity of native ant communities have been studied but its impacts on their functional ersity are unknown. Comparing invaded and uninvaded plots in tropical grasslands of Hong Kong, we investigated how the presence of S. invicta affects the ersity and distribution of ant species and traits within and across communities, the functional identities of communities, and functionally unique species. We calculated the functional ersity of in idual species, including the trait variation from intraspecific polymorphisms, and scaled up these values to calculate functional ersity at the community level. Invasion had only limited effects on species richness and functional richness, which were 13% and 8.5% lower in invaded communities respectively. In contrast, invasion had pronounced effects on taxonomic and functional composition due to turnover in species and trait values. Furthermore, invaded communities were functionally more homogeneous, displaying 23% less turnover and 56% more redundancy than uninvaded communities, as well as greater clustering and lower ergence in trait values. Invaded communities had fewer functionally-unique in iduals and were characterized by ant species with narrower heads and bodies and shorter mandibles. Our results suggest that studies based only on taxonomic measures of ersity or indices describing trait variety risk underestimating the full ramifications of invasions. Investigating the ersity and distributions of traits at species, community and landscape levels can reveal the cryptic impacts of alien species which, despite causing little taxonomic change, may substantially modify the structure and functioning of ecological communities.
Publisher: Cold Spring Harbor Laboratory
Date: 18-12-2022
DOI: 10.1101/2022.12.15.520573
Abstract: Tropical forests are threatened by degradation and deforestation but the consequences for these ecosystems are poorly understood, particularly at the landscape scale. We present the most extensive ecosystem analysis to date of the impacts of logging and conversion of tropical forest to oil palm from a large-scale study in Borneo, synthesizing responses from 79 variables categorized into four hierarchical ecological ‘levels’: 1) structure and environment, 2) species traits, 3) bio ersity and 4) ecosystem functions. Variables at the lowest levels that were directly impacted by the physical processes of timber extraction, such as soil characteristics, were sensitive to even moderate amounts of logging, whereas bio ersity and ecosystem functions proved remarkably resilient to logging in many cases, but were more affected by conversion to oil palm plantation. Logging tropical forest mostly impacts structure while bio ersity and functions are more vulnerable to habitat conversion
Publisher: Wiley
Date: 19-12-2018
DOI: 10.1002/EAT.22976
Abstract: Prolonged exposure to large/small bodies causes aftereffects in perceived body size. Outside the laboratory, in iduals repeatedly exposed to small (large) bodies tend to over- (under-) estimate their size and exhibit increased (decreased) body dissatisfaction. Why, among in iduals exposed to approximately equivalent distributions of body sizes, only some develop body size and shape misperception and/or body dissatisfaction is not yet fully understood. We exposed 61 women to high and low adiposity bodies simultaneously, instructing half to attend to high, and half to low adiposity bodies. Participants in the high adiposity attention condition's perception of "normal" body size significantly increased in adiposity, and vice versa. This suggests that visual attention moderates body size aftereffects. Interventions encouraging visual attention to more realistic ranges of bodies may therefore reduce body misperception. No change in body dissatisfaction was found, suggesting that changes in the perceptual component (misperception) may not necessarily affect the attitudinal component (dissatisfaction) of body image distortion.
Publisher: The Royal Society
Date: 29-06-2022
Abstract: The assumption that differences in species' traits reflect their different niches has long influenced how ecologists infer processes from assemblage patterns. For instance, many assess the importance of environmental filtering versus classical limiting-similarity competition in driving biological invasions by examining whether invaders’ traits are similar or dissimilar to those of residents, respectively. However, mounting evidence suggests that hierarchical differences between species' trait values can distinguish their competitive abilities (e.g. for the same resource) instead of their niches. Whether such trait-mediated hierarchical competition explains invasions and structures assemblages is less explored. We integrate morphological, dietary, physiological and behavioural trait analyses to test whether environmental filtering, limiting-similarity competition or hierarchical competition explain invasions by fire ants on ant assemblages. We detect both competition mechanisms invasion success is not only explained by limiting similarity in body size and thermal tolerance (presumably allowing the invader to exploit different niches from residents), but also by the invader's superior position in trait hierarchies reflecting competition for common trophic resources. We find that the two mechanisms generate complex assemblage-level functional ersity patterns—overdispersion in some traits, clustering in others—suggesting their effects are likely missed by analyses restricted to a few traits and composite trait ersity measures.
Publisher: Public Library of Science (PLoS)
Date: 03-06-2016
Publisher: The Royal Society
Date: 06-2018
DOI: 10.1098/RSOS.172103
Abstract: Prolonged visual exposure, or ‘adaptation’, to thin (wide) bodies causes a perceptual aftereffect such that subsequently seen bodies appear wider (thinner) than they actually are. Here, we conducted two experiments investigating the effect of rotating the orientation of the test stimuli by 90° from that of the adaptor. Aftereffects were maximal when adapting and test bodies had the same orientation. When they differed, the axis of the perceived distortion changed with the orientation of the body. Experiment 1 demonstrated a 58% transfer of the aftereffect across orientations. Experiment 2 demonstrated an even greater degree of aftereffect transfer when the influence of low-level mechanisms was reduced further by using adaptation and test stimuli with different sizes. These results indicate that the body aftereffect is mediated primarily by high-level object-based processes, with low-level retinotopic mechanisms playing only a minor role. The influence of these low-level processes is further reduced when test stimuli differ in size from adaptation stimuli.
Publisher: Wiley
Date: 21-12-2012
Publisher: Wiley
Date: 21-12-2020
DOI: 10.1111/ECOG.05505
Abstract: Interspecific competition, a dominant process structuring ecological communities, is influenced by species' phenotypic differences. Limiting similarity theory holds that species with similar traits should compete intensely (‘trait‐similarity'). In contrast, competing theories including modern coexistence theory emphasize that species with traits conferring competitive advantages should outcompete others (‘trait‐hierarchy'). Either or both of these mechanisms may drive competitive exclusion, but their relative importance and interacting effects are rarely studied. Here, we explore empirically whether trait‐similarity and trait‐hierarchy can explain fine‐scale spatial associations observed between invasive and native ant species in a tropical assemblage. We find that pairwise co‐occurrences between the invasive red imported fire ant Solenopsis invicta and 28 other species across relatively homogenous grasslands can be explained largely by an interaction of trait‐similarity and trait‐hierarchy in a single morphological trait, relative pronotum width. Specifically, higher trait‐hierarchy values are associated with negative co‐occurrences however, these effects are counteracted when species are increasingly dissimilar in their trait ranges. These findings are consistent with the notion that limiting similarity and competitive hierarchies are interactive rather than discrete mechanisms driving competitive exclusion.
Publisher: Wiley
Date: 22-01-2020
DOI: 10.1111/OIK.06870
Publisher: Cold Spring Harbor Laboratory
Date: 22-07-2020
DOI: 10.1101/2020.07.21.213678
Abstract: The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila -parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5° Celsius in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5-9 host and 5-11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are erse enough to be representative, yet still amenable to field and laboratory experiments.
Publisher: Elsevier
Date: 2013
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Owen Lewis.