Large Geographic Scales Research Articles

Ecogeographical patterns in owl plumage colouration: Climate and vegetation cover predict global colour variation

AbstractAimEcogeographical rules link animal colours, especially those produced by melanin pigments, with variation in environmental conditions over wide geographical scales. In particular, Gloger’s rule, coined for endothermic animals in two versions, suggests that tegument darkness should increase at high temperature, as well as in highly humid environments. On the other hand, the thermal melanism hypothesis predicts that darker colourations should be more frequent in colder areas given their thermoregulation benefits.LocationGlobal.Time periodContemporary.Major taxa studiedStrigiformes.MethodsHere, we provide a global comparative test of these contrasting expectations in all extant owls (n = 198 species), a group of nocturnal birds displaying huge variability in the degree of melanin‐based plumage colouration and environmental specialization. Combining analyses at both species and assemblage level, we assessed the climatic and environmental variables explaining variation in plumage lightness and redness across broad geographical gradients.ResultsDarker and redder owl phenotypes are more likely found near the equator. Species and assemblage level analyses reveal that owls have more frequently darker and redder plumages in warmer regions. In addition, owl species living in more vegetated areas are darker, and owl assemblages show darker colours in wetter areas.Main conclusionsGlobal patterns of colour variation in owls do not fit expectations from the thermal melanism hypothesis but support Gloger’s rule. Our findings also stress that several alternative selective forces may explain climatic effects on colouration over large geographical scales. Experimental work is urged to uncover the possible mechanisms behind the detected associations between owl colour and environmental variables.

Climate differently influences the genomic patterns of two sympatric marine fish species.

Climate influences population genetic variation in marine species. Capturing these impacts remains challenging for marine fishes which disperse over large geographical scales spanning steep environmental gradients. It requires the extensive spatial sampling of individuals or populations, representative of seascape heterogeneity, combined with a set of highly informative molecular markers capable of revealing climatic-associated genetic variations. We explored how space, dispersal and environment shape the genomic patterns of two sympatric fish species in the Mediterranean Sea, which ranks among the oceanic basins most affected by climate change and human pressure. We hypothesized that the population structure and climate-associated genomic signatures of selection would be stronger in the less mobile species, as restricted gene flow tends to facilitate the fixation of locally adapted alleles. To test our hypothesis, we genotyped two species with contrasting dispersal abilities: the white seabream Diplodus sargus and the striped red mullet Mullus surmuletus. We collected 823 individuals and used genotyping by sequencing (GBS) to detect 8,206 single nucleotide polymorphisms (SNPs) for the seabream and 2,794 for the mullet. For each species, we identified highly differentiated genomic regions (i.e. outliers) and disentangled the relative contribution of space, dispersal and environmental variables (climate, marine primary productivity) on the outliers' genetic structure to test the prevalence of gene flow and local adaptation. We observed contrasting patterns of gene flow and adaptive genetic variation between the two species. The seabream showed a distinct Alboran sea population and panmixia across the Mediterranean Sea. The mullet revealed additional differentiation within the Mediterranean Sea that was significantly correlated to summer and winter temperatures, as well as marine primary productivity. Functional annotation of the climate-associated outlier SNPs then identified candidate genes involved in heat tolerance that could be examined to further predict species' responses to climate change. Our results illustrate the key steps of a comparative seascape genomics study aiming to unravel the evolutionary processes at play in marine species, to better anticipate their response to climate change. Defining population adaptation capacities and environmental niches can then serve to incorporate evolutionary processes into species conservation planning.

Spatial difference of climate change effects on wheat protein concentration in China

Climate change effects on global food security are not only limited to its effects on the yield of cereals but also their nutritional quality. However, climate change effects on crop nutritional quality, particularly grain protein concentration (PC) on a large geographical scale have not yet been quantified in China. For this purpose, we assessed the effects of three key climatic factors (temperature, precipitation, and solar radiation) on wheat PC in ten wheat-growing areas of China using a series of statistical models on a county-level PC dataset. The results demonstrated that the average PC in China from 2006 to 2018 ranged from 12.01% to 14.50% across the ten areas, with an obvious spatial difference pattern showing an increase in PC from south to north and from west to east. The sensitivity analysis indicated that PC showed a positive response to variation in the increasing temperature, and the PC of wheat grown in the Huanghuai area was less affected than the PC of wheat grown in other areas. Conversely, solar radiation posed negative effects on the PC in the southwestern area, whereas precipitation had intricate effects on the PC in all areas. Besides, the highest explanation of climate variability during five growth periods contributed 26.0%–47.6% of the PC variability in the northeastern area, whereas the lowest explanation of climate variability during five growth periods only accounted for 2.5%–3.7% of PC variability in the Yangtze River area. Our study further demonstrated that the effects of climate change on wheat grain PC in China were spatially heterogeneous with higher effects on PC in spring wheat-growing areas as compared to winter wheat-growing areas. We suggested that the northern and the northeastern area in China could be developed as alternative areas to produce wheat with high grain PC in the face of climate warming.

The Prescription of Drug Ontology 2.0 (PDRO): More Than the Sum of Its Parts.

While drugs and related products have profoundly changed the lives of people around the world, ongoing challenges remain, including inappropriate use of a drug product. Inappropriate uses can be explained in part by ambiguous or incomplete information, for example, missing reasons for treatments, ambiguous information on how to take a medication, or lack of information on medication-related events outside the health care system. In order to fully assess the situation, data from multiple systems (electronic medical records, pharmacy and radiology information systems, laboratory management systems, etc.) from multiple organizations (outpatient clinics, hospitals, long-term care facilities, laboratories, pharmacies, registries, governments) on a large geographical scale is needed. Formal knowledge models like ontologies can help address such an information integration challenge. Existing approaches like the Observational Medical Outcomes Partnership are discussed and contrasted with the use of ontologies and systems using them for data integration. The PRescription Drug Ontology 2.0 (PDRO 2.0) is then presented and entities that are paramount in addressing this problematic are described. Finally, the benefits of using PDRO are discussed through a series of exemplar situation.

Site fidelity and shallow genetic structure in the common smooth-hound shark Mustelus mustelus confirmed by tag-recapture and genetic data.

The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species' distribution in southern Africa based on a combination of molecular and long-term tag-recapture data. Eight species-specific microsatellite markers (N=73) and two mitochondrial genes, nicotinamide adenine dehydrogenase subunit 4 and control region (N=45), did not reveal any significant genetic structure among neighbouring sites. Nonetheless, tagging data demonstrate a remarkable degree of site fidelity with 76% of sharks recaptured within 50 km of the original tagging location. On a larger geographic scale, dispersal is governed by oceanographic features as demonstrated by the lack of movements across the Benguela-Agulhas transition zone separating the South-East Atlantic Ocean (SEAO) and South-West Indian Ocean (SWIO) populations. Microsatellite data supported very shallow ocean-based structure (SEAO and SWIO) and historical southward gene flow following the Agulhas Current, corroborating the influence of this dynamic oceanographic system on gene flow. Moreover, no movements between Namibia and South Africa were observed, indicating that the Lüderitz upwelling formation off the Namibian coast acts as another barrier to dispersal and gene flow. Overall, these results show that dispersal and stock structure of M. mustelus are governed by a combination of behavioural traits and oceanographic features such as steep temperature gradients, currents and upwelling systems.

Performance and Deployment of Low-Cost Particle Sensor Units to Monitor Biomass Burning Events and Their Application in an Educational Initiative.

Biomass burning smoke is often a significant source of airborne fine particles in regional areas where air quality monitoring is scarce. Emerging sensor technology provides opportunities to monitor air quality on a much larger geographical scale with much finer spatial resolution. It can also engage communities in the conversation around local pollution sources. The SMoke Observation Gadget (SMOG), a unit with a Plantower dust sensor PMS3003, was designed as part of a school-based Science, Technology, Engineering and Mathematics (STEM) project looking at smoke impacts in regional areas of Victoria, Australia. A smoke-specific calibration curve between the SMOG units and a standard regulatory instrument was developed using an hourly data set collected during a peat fire. The calibration curve was applied to the SMOG units during all field-based validation measurements at several locations and during different seasons. The results showed strong associations between individual SMOG units for PM2.5 concentrations (r2 = 0.93–0.99) and good accuracy (mean absolute error (MAE) < 2 μg m−3). Correlations of the SMOG units to reference instruments also demonstrated strong associations (r2 = 0.87–95) and good accuracy (MAE of 2.5–3.0 μg m−3). The PM2.5 concentrations tracked by the SMOG units had a similar response time as those measured by collocated reference instruments. Overall, the study has shown that the SMOG units provide relevant information about ambient PM2.5 concentrations in an airshed impacted predominantly by biomass burning, provided that an adequate adjustment factor is applied.

Effects of biotic and abiotic drivers on the growth rates of individual trees in temperate natural forests

Understanding the driving factors for individual tree growth is of great significance to devise effective forest management strategies. Such information can be used to select appropriate tree harvesting times, and to provide valuable guidance for creating suitable local environmental conditions during the period of tree growth. However, currently it remains unclear how biotic and abiotic factors affect individual tree growth on large geographical scales. In the present study, based on a dataset from 457 field plots and the growth records of 7,560 individual trees in natural forests in northeastern China, the effects of tree size, local environmental conditions, and regional climate characteristics on the 5-year basal area increment (BAI) of the three dominant species (Quercus mongolica, Betula platyphylla, and Larix gmelinii) were investigated using nonlinear mixed-effects models. Although the magnitude and direction of the drivers’ effects on the BAI differed among the three species, the following variables explained major proportions of the variation (conditional R2 ranging from 0.57 to 0.66) in the BAI: 1) Diameter at breast height; 2) Mean temperature and precipitation during the growing seasons; and 3) Species mingling and the basal areas of larger trees. In addition, an interactive effect between temperature and precipitation was significant for Q. mongolica. On the basis of our results, we identified the most important variables among multiple drivers affecting the growth of individual trees, and developed individual tree growth models for the three species. Our results provide an initial basis for the future scientific management of some of the most important natural forest regions in the world.

A completely resolved phylogenetic tree of British spiders (Arachnida: Araneae)

The recent accumulation of increasingly densely sampled phylogenetic analyses of spiders has greatly advanced our understanding of evolutionary relationships within this group. Here, this diverse literature is reviewed and combined with earlier morphological analyses in an attempt to reconstruct the first fully resolved phylogeny for the spider fauna of the British Isles. The resulting tree highlights parts of the group where data are still too limited for a confident assessment of relationships, proposes a number of deviations from previously suggested phylogenetic hypotheses, and can serve as a framework for evolutionary and ecological interpretations of the biology of British spiders, as well as a starting point for future studies on a larger geographical scale.

Dreaming in the shadow of history: micro-mobilities and belonging in Lucknow

ABSTRACT Spatial mobility is often considered on large geographical scales: people move from distant villages to global cities, they migrate from one country to the next, or even to a whole new continent. Such large-scale migration comes with shifts in economic position, social status and cultural exposure, shifts that condition new figurations of belonging – or so the argument goes. In contrast, I ethnographically follow the looping movements of three young men in Lucknow who aspire to migrate but remain stuck, who find a whole new world by crossing the river, whose small steps reflect big dreams. As the world grapples with ‘lockdowns’ and ‘stuckedness’ in the Covid-19 pandemic, I sketch their aspirations, mental maps and the material restraints that condition their trajectories. Through them, I demonstrate how looping micro-mobilities – cruising through the night, dancing on stage, riding one's bike – can be as effective in fostering new figurations of belonging as the grand movements emphasized in literature on migration. I further explore which spaces enable and contain such micro-mobilities, rediscovering the potency of urban settings to make people feel at home and out of place in small but important ways.

A Multi-perspective Narrative-Based Geovisualization Dashboard for the 2020 US Presidential Election

In this paper, we design and implement a map dashboard that combines spatio-temporal visualization and interactive narrative to comprehensively illustrate the 2020 US presidential election. Specifically, our dashboard takes campaign rallies and major events as narrative clues and integrates multi-perspective factors (e.g., the spatial spread of COVID-19, social distancing adherence, poll results) for visualization and statistical analysis. Compared with traditional methods and products, our integrated multi-perspective solution better balances the narrative property and the geovisualization property of a dashboard, making it suitable for illustrating social or political events that happened on a large geographic scale. The result shows that our narrative-based geovisualization dashboard may be used for demonstrating and associating multiple factors with partisanship and has the potential to help users explore the interaction between policies controlling COVID-19, social distancing, and partisanship across the country during the 2020 US presidential election.

Choked out: Battling invasive giant cane along the Rio Grande/Bravo Borderlands

AbstractAlong the U.S.‐Mexico border, an aggressive non‐native grass, giant cane (Arundo donax), grows in dense, nearly impenetrable stands along hundreds of kilometers of the Rio Grande/Bravo (RGB). Between 2008 and 2018, a diverse, multisector binational‐team repeatedly treated giant cane with prescribed fire and herbicide along 90 km of this binational river to restore aquatic and riparian habitat and native plant community composition. The large geographic scale, binational management response, treatment methods used, and development of a long‐term monitoring program to quantify treatment impacts on the RGB's riparian plant community underscore the unique aspects of this effort. Results of this decade‐long management experiment indicate that (i) the combination of a primary treatment of giant cane (using prescribed fire followed 4–6 weeks later by herbicide treatment of regrowth) and a secondary treatment (spot treatment of regrowth one or more years following primary treatment) was effective in reducing the extent and distribution of giant cane at relatively low cost, (ii) giant cane re‐establishment following treatment is often not rapid, nor dramatic; and (iii) as revealed by analysis of riparian vegetation monitoring data, eradication of dense stands of giant cane have fostered significant and long‐term reduction in giant cane cover and recovery of native woody riparian plant taxa. Important caveats to the long‐term viability of managing giant cane hinge on better understanding the consequences of herbicide use, securing funding to cover the cost of re‐treatment, and continuing river flow management focused on promoting the recovery of native riparian obligate plants over non‐natives.

The core seed mycobiome of Pseudotsuga menziesii var. menziesii across provenances of the Pacific Northwest, USA

ABSTRACT Fungal symbionts occur in all plant tissues, and many aid their host plants with critical functions, including nutrient acquisition, defense against pathogens, and tolerance of abiotic stress. “Core” taxa in the plant mycobiome, defined as fungi present across individuals, populations, or time, may be particularly crucial to plant survival during the challenging seedling stage. However, studies on core seed fungi are limited to individual sampling sites, raising the question of whether core taxa exist across large geographic scales. We addressed this question using both culture-based and culture-free techniques to identify the fungi found in individual seeds collected from nine provenances across the range of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii), a foundation tree species in the Pacific Northwest and a globally important timber crop that is propagated commercially by seed. Two key findings emerged: (i) Seed mycobiome composition differed among seed provenances. (ii) Despite variation in the seed mycobiome, we detected four core members, none of which is a known pathogen of Douglas-fir: Trichoderma spp., Hormonema macrosporum, Mucor plumbeus, and Talaromyces rugulosus. Our results support the concept of a core seed microbiome, yet additional work is needed to determine the functional consequences of core taxa for seedling germination, growth, survival, and competition.

The geography of diet variation in Neotropical Carnivora

Abstract Mammalian carnivores (order Carnivora) perform important regulatory functions in terrestrial food webs. Building a comprehensive knowledge of the dietary patterns of carnivorans and the factors determining such patterns is essential for improving our understanding of the role of carnivorans in ecosystem functioning. In the Neotropics, there are 64 extant species of terrestrial Carnivora, but information on their trophic ecology is diffuse. We compiled and analysed the available quantitative dietary data for Neotropical carnivorans, aiming to detect patterns of intraspecific and interspecific dietary variation at a large geographical scale. The resulting database encompasses information on trophic interactions of 37 native carnivoran species from six families across 14 countries. There are clear geographical biases towards southern Brazil, Chile, and Argentina, and a noticeable knowledge gap within the Amazon. Also, most studies are focused on canids and felids, especially Puma concolor, Panthera onca, Cerdocyon thous, Leopardus pardalis, and Chrysocyon brachyurus, whereas for 27 native species, we found no quantitative dietary information. Neotropical carnivorans consume species from at least 651 genera of vertebrates, invertebrates, and plants. We found clear species‐specific dietary patterns and marked differences between Neotropical felids and canids. Although predators generally exhibit high levels of consistency in their diets regarding prey body mass, we detected significant intraspecific variation for all species analysed across study sites. Body mass imposes strong constraints on prey use, but biogeographical differences in prey availability and human influence may drive the geographical variation we found. Overall, observed patterns show not only similarities with resource‐use patterns found for carnivorans in other continents, such as nestedness driven by body mass, but also differences, such as high levels of frugivory and consumption of invertebrates by canids. Assessing resource‐use patterns is the first step towards a better understanding of processes underlying the organisation of trophic interactions, and is imperative for addressing impacts of defaunation on ecosystems and for informing conservation efforts.

Genetic diversity in a long-lived mammal is explained by the past's demographic shadow and current connectivity.

Within-species genetic diversity is crucial for the persistence and integrity of populations and ecosystems. Conservation actions require an understanding of factors influencing genetic diversity, especially in the context of global change. Both population size and connectivity are factors greatly influencing genetic diversity; the relative importance of these factors can, however, change through time. Hence, quantifying the degree to which population size or genetic connectivity are shaping genetic diversity, and at which ecological time scale (past or present), is challenging, yet essential for the development of efficient conservation strategies. In this study, we estimated the genetic diversity of 42 colonies of Rhinolophus hipposideros, a long-lived mammal vulnerable to global change, sampling locations spanning its continental northern range. Here, we present an integrative approach that disentangles and quantifies the contribution of different connectivity measures in addition to contemporary colony size and historic bottlenecks in shaping genetic diversity. In our study, the best model explained 64% of the variation in genetic diversity. It included historic bottlenecks, contemporary colony size, connectivity and a negative interaction between the latter two. Contemporary connectivity explained most genetic diversity when considering a 65km radius around the focal colonies, emphasizing the large geographic scale at which the positive impact of connectivity on genetic diversity is most profound and hence, the minimum scale at which conservation should be planned. Our results highlight that the relative importance of the two main factors shaping genetic diversity varies through time, emphasizing the relevance of disentangling them to ensure appropriate conservation strategies.

Predicting spatiotemporally-resolved air temperature over Sweden from satellite data using an ensemble model

BACKGROUND AND AIM: Mapping of air temperature (Ta) at high spatiotemporal resolution is critical to reduce exposure assessment errors in epidemiological studies on the health effects of air temperature. We aimed to predict daily Ta at a spatial resolution of 1×1 km2 from 2001 to 2019 using an ensemble model based on the satellite-based daily land surface temperature. The results will provide insights in modeling Ta with an ensemble model to reduce exposure measurement error and serve as a foundation for epidemiological studies on the short-term and long-terms effects of air temperature on public health at a large geographical scale. METHODS: The generalized additive model based ensemble model incorporated four base models, including a generalized additive model, a generalized additive mixed model, and two machine learning models (random forest and extreme gradient boosting), and allowed the weights for each model to vary over space, with the best-performing model for each grid cell assigned the highest weight. RESULTS:The ensemble model showed high performance with an overall R2 of 0.98 and a root mean square error of 1.38 °C in the ten-fold cross-validation, and outperformed each of the four base models. Among base models, the two machine learning models outperformed the two regression models. In the machine learning models, Ts was the dominant predictor of Ta, followed by day of year, Normalized Difference Vegetation Index, latitude, elevation, and longitude. CONCLUSIONS:The GAM-based ensemble model exploited the predictive ability of base models by allowing the weights for each model to vary over space, and provided an improved estimation of air temperature over Sweden that outperformed estimations from each base model. Among the base models, two machine learning methods (RF and XGBoost) exhibited higher predictive power than two linear regression models. The estimations from ensemble models can be applied in epidemiological studies to minimize bias caused by exposure misclassification. KEYWORDS: random forest, extreme gradient boosting, generalized additive model, ensemble model, air temperature, health exposure

Assessing changes to ecosystem service values at large geographic scale: A case study for Australia’s Great Barrier Reef

Climate change is impacting numerous natural world heritage sites – the Great Barrier Reef (GBR) being just one. There are calls for interventions to help sustain reef values in the face of climate change and while there are numerous techniques for assessing impacts on non-market values, most struggle to generate robust estimates for large and complex systems. This complicates the assessment of potential benefits of reef interventions. Focusing on corals in the GBR, we develop and apply a systematic, evaluative framework that combines insights from a coral-reef simulation model with those from research on reef-related ecosystem services (ES). We estimate the market and non-market benefits of complete control of coral-eating crown-of-thorns starfish (CoTS) and global climate mitigation. By comparing the present value of ES with and without interventions, we can assess their potential benefits: between $5b and $28.5b depending on intervention and discount rate. Our empirical insights are specifically relevant to the GBR. Our generic approach to assessing the potential value of CoTS control at large scale and in data/knowledge-poor environments can be developed further and adapted to other interventions.

Phenotypic integration approaches predict a decrease of reproduction rates of Caribbean pine populations in dry tropical areas

• Key message The combination of structural equation modelling and linear mixed-effects models opens a new perspective to investigate trait adaptation syndromes through phenotypic integration prediction at large geographical scales, a necessary step to understand the future of organisms under climate change. In the case of Pinus caribaea Morelet, reproduction limits the species suitability, decreasing towards southernmost latitudes where dry conditions increase.ContextCaribbean pine is an ecologically and economically important species planted in all the tropical regions of the world, where it shows optimal growth and survival but low reproduction rates.AimsThis study investigates Caribbean pine fitness-related traits, accounting for phenotypic plasticity and local adaptation, to detect co-variation among traits and predict their relationship across the tropics.MethodsI re-analysed earlier data of survival, growth, reproduction, stem quality and development stage from 25 provenances of Caribbean pine planted in 16 trials in the tropical regions in a two-step modelling approach including (i) structural equation modelling (SEM) based on the current knowledge of the species and theoretical expectations coming from other species; (ii) mixed-effects model accounting for trait-relationships as defined by SEM and allowing for trait prediction.ResultsGrowth, survival and reproduction showed a slight but significant provenance effect indicating population differentiation and a positive co-variation between growth and reproduction, suggesting that trees reached optimal growth before they reproduced. Models predicted low reproduction rates of Caribbean pine across the tropics, decreasing towards southern latitudes where dry conditions increased.ConclusionThis study opens new perspectives to investigate trait adaptation syndromes through phenotypic integration prediction at large geographical scales.

Can Urban Forest Settings Evoke Positive Emotion? Evidence on Facial Expressions and Detection of Driving Factors

There is increasing interest in experiences of urban forests because relevant studies have revealed that forest settings can promote mental well-being. The mental response to a forest experience can be evaluated by facial expressions, but relevant knowledge is limited at large geographical scales. In this study, a dataset of 2824 photos, detailing the evaluated age (toddler, youth, middle-age, and senior citizen) and gender of urban forest visitors, was collected from Sina Weibo (a social media application similar to Twitter in China) between 1–7 October 2018, in 12 randomly chosen cities in China. Happy and sad expressions were rated as scores by FireFACE software V1.0, and the positive response index (PRI) was calculated by subtracting sad scores from happy scores. Regional environmental factors were collected to detect driving forces using regression analyses. Happy scores were higher in forests than in urban settings, while sad scores for toddlers were lower in forests than in promenades and squares. Females showed more positive emotional expressions than males. Increases in happy scores were driven by the increase of daily minimum temperature; while PRI declined with increases in latitude. Overall, an urban forest experience can evoke positive emotions, which is likely due to comfortable feelings in warm temperatures.

Calcium and pH interaction limits bloom formation and expansion of a nuisance microalga

AbstractMicroalgal range expansions are increasing in frequency and magnitude but generally remain unnoticed until mass development occurs. Gonyostomum semen is a freshwater raphidophyte that causes nuisance blooms in lakes and has recently expanded its distribution across Europe. G. semen was considered to mainly occur in humic lakes in the boreal region but is now found in high density also in other freshwater habitats on a larger geographic scale with growing incidence. In this study, we focused on which environmental factors limit its expansion. Our hypothesis was that G. semen occurs in many different lake types, except for high alkalinity lakes, in which high pH in combination with high calcium concentration would inhibit its growth. Results from our field study illustrate the environmental heterogeneity of G. semen bloom sites across Europe and the United States. Nevertheless, none of these sites combined high pH and high calcium concentration. In a mesocosm study, as well as a laboratory experiment, we further demonstrated that growth of G. semen is inhibited in conditions combining both high pH and high calcium concentration. We also discuss the function of Sphagnum peat mosses in rendering an alkaline habitat suitable to G. semen growth. Our study highlights that high alkalinity environments act as a major colonization barrier to G. semen. While this finding explains which environmental filters limit G. semen distribution it also helps in understanding its current expansion. With globally decreasing calcium concentrations in freshwater ecosystems, new habitats have and will become conducive to G. semen growth.

Effects of human footprint and biophysical factors on the body-size structure of fished marine species.

Marine fisheries in coastal ecosystems in many areas of the world have historically removed large‐bodied individuals, potentially impairing ecosystem functioning and the long‐term sustainability of fish populations. Reporting on size‐based indicators that link to food‐web structure can contribute to ecosystem‐based management, but the application of these indicators over large (cross‐ecosystem) geographical scales has been limited to either fisheries‐dependent catch data or diver‐based methods restricted to shallow waters (<20 m) that can misrepresent the abundance of large‐bodied fished species. We obtained data on the body‐size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo‐video (stereo‐BRUV). Sampling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No‐take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal‐size fishes typically declined as human impact increased. Our large‐scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no‐take marine reserves in protecting large‐bodied fishes across a broad range of species and ecosystem configurations.