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To evaluate how factors acting at different spatial scales influence range limits in bird species of the Colombian Andes. Andes Mountains of Colombia. We used M axent, a climate envelope model (CEM), and environmental and geographic information to study range-filling (i.e. the extent to which a species occurs in all the areas in which it is predicted to occur) in 70 range-restricted bird species of the Colombian Andes. Environmental data were taken from the WorldClim database, and species occurrence data were taken from museum data collated by the BioMap project, an observational database, and the literature. We evaluated how climate and geographic barriers may shape range limits at two scales. At a broad extent (i.e. across the three main cordilleras within the Colombian Andes), we find that CEMs predict there to be suitable environmental conditions for particular species in regions where the species is absent, possibly as a result of dispersal limitation or biotic interactions. In contrast, at a finer scale (within a given cordillera), species generally occur across the entire area predicted to be suitable by a given CEM. Geographic discontinuities within cordilleras do not generally correspond to range limits; instead, range limits correspond to changes in environmental conditions. Our results suggest that different mechanisms influence the presence of species at different scales. Dispersal limitation, potentially combined with species interactions, may influence range limits at a broad extent (the entire Colombian Andes), while strong environmental gradients correspond to range limits at a finer scale (within a cordillera).

Human activities have shaped large-scale distributions of many species, driving both range contractions and expansions. Species differ naturally in range size, with small-range species concentrated in particular geographic areas and potentially deviating ecologically from widespread species. Hence, species’ responses to human activities may be influenced by their geographic range sizes, but if and how this happens are poorly understood. Here, we use a comprehensive distribution database and species distribution modeling to examine if and how human activities have affected the extent to which 9,701 vascular plants fill their climatic potential ranges in China. We find that narrow-ranged species have lower range filling and widespread species have higher range filling in the human-dominated southeastern part of China, compared with their counterparts distributed in the less human-influenced northwestern part. Variations in range filling across species and space are strongly associated with indicators of human activities (human population density, human footprint, and proportion of cropland) even after controlling for alternative drivers. Importantly, narrow-ranged and widespread species show negative and positive range-filling relationships to these human indicators, respectively. Our results illustrate that floras risk biotic homogenization as a consequence of anthropogenic activities, with narrow-ranged species becoming replaced by widespread species. Because narrow-ranged species are more numerous than widespread species in nature, negative impacts of human activities will be prevalent. Our findings highlight the importance of establishing more protected areas and zones of reduced human activities to safeguard the rich flora of China.

Geographic range size has long fascinated ecologists and evolutionary biologists, yet our understanding of the factors that cause variation in range size among species and across space remains limited. Not only does geographic range size inform decisions about the conservation and management of rare and nonindigenous species due to its relationship with extinction risk, rarity, and invasiveness, but it also provides insights into fundamental processes such as dispersal and adaptation. There are several features unique to plants (e.g. polyploidy, mating system, sessile habit) that may lead to distinct mechanisms explaining variation in range size. Here, we highlight key studies testing intrinsic and extrinsic hypotheses about geographic range size under contrasting scenarios where species’ ranges are static or change over time. We then present results from a meta-analysis of the relative importance of commonly hypothesized determinants of range size in plants. We show that our ability to infer the relative importance of these determinants is limited, particularly for dispersal ability, mating system, ploidy, and environmental heterogeneity. We highlight avenues for future research that merge approaches from macroecology and evolutionary ecology to better understand how adaptation and dispersal interact to facilitate niche evolution and range expansion.

Designing highly reliable and practical microwave absorbers is one of the most important research directions in the microwave absorbing field. Many absorbents suffer from concentration-sensitivity and environmental-sensitivity dilemmas in practical applications. Here, sea urchin-like aggregates of MnO 2 nanotubes were synthesized by a simple hydrothermal method, which exhibit an outstanding impedance matching characteristic. The composites based on sea urchin-like aggregates of MnO 2 nanotubes show excellent microwave absorption performance in a wide concentration domain from 20 wt.% to 70 wt.%, corresponding to electrical conductivities from 1.86 × 10 −7 to 1.85 × 10 −5 S/m. Such a wide concentration range of absorbent for excellent microwave absorption is mainly attributed to the beneficial impedance matching properties of sea urchin-like aggregates of hollow nanotubes. A competitive absorption bandwidth of 3.36 GHz is achieved at 1 mm thickness, which can be broadened to 13.4 GHz by structural design. This work shows a new scheme for designing reliable and practical microwave absorbers benefit from the wide absorbent concentration domain.

AIM: Understanding the factors that govern species' geographical ranges is of utmost importance for predicting potential range shifts triggered by environmental change. Species ranges are partially limited by their tolerances to extrinsic environmental conditions such as climate and habitat. However, they are also determined by the capacity of species to disperse, establish new populations and proliferate, which are in turn dependent on species intrinsic life‐history traits. So far, the contribution of intrinsic factors driving species distributions has been inconclusive, largely because intrinsic and extrinsic factors have not been examined simultaneously in a satisfactory way. We investigate how geographical ranges of plants are determined by both extrinsic environmental factors and species intrinsic life‐history traits. LOCATION: Europe. METHODS: We compiled a database on plant geographical ranges, environmental tolerances and life‐history traits that constitutes the largest dataset analysed to date (1276 species). We used generalized linear modelling to test if range size and range filling (the proportion of climatically suitable area a species occupies) are affected by dispersal distance, habitat breadth and 10 life‐history traits related to establishment and proliferation. RESULTS: The species characteristics that were most linked to range limitations of European plant species were dispersal potential, seed bank persistence and habitat breadth (which together explained ≥ 30% of deviance in range filling and range size). Specific leaf area, which has been linked to establishment ability, made a smaller contribution to native range limitations. MAIN CONCLUSIONS: Our results can be used to improve estimates of extinction vulnerability under climate change. Species with high dispersal capacity, that can maintain viable seed banks for several years and that can live in an intermediate number of habitats have the fewest non‐climatic limitations on their ranges, and are most likely to shift their geographical ranges under climate change. We suggest that climate‐change risk assessments should not focus exclusively on dispersal capacity.

Aim: To investigate the contribution to range filling, range extent and climatic niche space of species of information contained in the largest databank of digitized biodiversity data: the global biodiversity information facility (GBIF). We compared such information with a compilation of independent distributional data from natural history collections and other sources. Location: Europe. Methods: We used data for the hawkmoths (Lepidoptera, family Sphingidae) to assess three aspects of range information: (1) observed range filling in 100 km × 100 km grid cell squares, (2) observed European range extent and (3) observed climatic niche. Range extents were calculated as products of latitudinal and longitudinal extents. Areas derived from minimum convex polygons drawn onto a 2-dimensional niche space representing the two main axes of a principal component analysis (PCA) were used to calculate climatic niche space. Additionally, record-based permutation tests for niche differences were carried out. Results: We found that GBIF provided many more distribution records than independent compilation efforts, but contributed less information on range filling, range extent and climatic niches of species. Main conclusions: Although GBIF contributed relevant additional information, it is not yet an effective alternative to manual compilation and databasing of distributional records from collections and literature sources, at least in lesser-known taxa such as invertebrates. We discuss possible reasons for our findings, which may help shape GBIF strategies for providing more informative data.

Aim The assumption that the native distributions of species are in equilibrium with climate has been shown to be frequently violated, despite its centrality to many niche model applications. We currently lack a framework that predicts these violations. Here, we examine whether variation in climatic disequilibrium is structured by properties of species’ native distributions and climatic niches. Location Global. Methods We built climatic niche models for 106 pine (Pinus L.) species, including 25 that have naturalized outside their native range. We measured the extent of climate space occupied exclusively by naturalized populations and considered what fraction of this space was available within the native continent and near the native range. We examined the consequences of disequilibrium for estimates of potential range filling and sister species niche conservatism. Results Most species (23 of 25) have naturalized in climate conditions outside the native niche, leading to increases in the total known suitable climate space. Increases in niche size were negatively related to native niche size. Increases were often large; one species expanded its niche by almost 10% of the global climate space. These increases were associated primarily with cooler, wetter and less seasonal climates. Increases in known niche size lowered potential range filling estimates within species’ native continent and ecoregion. Naturalized data did not strengthen support for niche conservatism among sister species. Main conclusions Among pines, climatic disequilibrium is the norm and not the exception. The magnitude of this disequilibrium can be vast, such that the native range greatly under‐represents the true climatic tolerances of some species. Fortunately, this disequilibrium can be predicted largely by the size of a species’ native niche. Accounting for this disequilibrium can improve our ability to characterize ecological phenomena, including potential range filling. This is an essential step towards improving the conservation value of ecological niche models.

Invasive trees are a major problem in South Africa. Many species are well established whereas others are still in the early stages of invasion. The management of invasive species is most cost effective at the early stages of invasion; it is thus essential to target and contain naturalizing invaders before they spread across the landscape. Multi-scale species distribution models (SDMs) provide useful insights to managers; they combine species-occurrence observations with climatic variables to predict potential distributions of alien species. Applying SDMs in human-dominated ecosystems is complicated because many factors associated with human actions interact in complex ways with climatic and edaphic factors to determine the potential suitability of sites for species. The aim of this study was to determine the degree to which a worldwide invader, A. altissima (Simaroubaceae) has occupied its potential range in South Africa, to identify areas at risk of future invasion. To do this we built a set of SDMs at both global and country scales using climatic, land use and human-footprint data. Climatic data best explained the distribution of A. altissima at the global scale whereas variables reflecting human-mediated disturbances were most influential at the national scale. Our analyses show the importance of human-mediated disturbances at a global scale and human occupancy at a country scale in determining the range limits of A. altissima. Populations of this tree species are already present in most parts of South Africa that are environmentally suitable for the species, and management actions need to focus on preventing increases in density in these areas.

AIM: At large spatial extents, the species richness of high‐level taxa is generally strongly positively correlated with temperature and precipitation, and consistently so across space and time. Here, we test whether this richness–climate relationship is driven by systematic associations between climate and characteristics of the geographical ranges of individual species. Specifically, we test the hypotheses that spatial variations in richness are driven by variations in species mean range size, climatic niche‐breadth, climatic range filling, frequency distribution of climatic niche position and/or frequency distribution of extant climatic conditions. LOCATION: The Americas. METHODS: We tested hypothetical effects of climatically constrained ranges on species richness using the breeding ranges of 3277 birds and 1659 mammals. We tallied species richness in 10⁴‐km² quadrats in the Americas as well as summary statistics describing the geographical ranges and climatic niches of the species occurring in each quadrat. We then used regression models to relate species richness to those characteristics. RESULTS: We found that species mean range size, climatic niche‐breadth and range filling were generally, but inconsistently, negatively related to species richness. As predicted, species richness per quadrat increased with the number of species having their climatic niches centred in the climatic conditions of the quadrats and with the geographical extent of those conditions, although these relationships were relatively weak. MAIN CONCLUSION: The richness–climate relationship appears to be largely decoupled from systematic variations in the characteristics of species climatic niches. Species generally have larger geographical ranges, wider climatic niches and higher range filling in species‐poor areas, each of which, all else being equal, should generate a richness–climate relationship the inverse of what we generally observe in nature. More species have their ranges centred on warm, wet and common climatic conditions. However, temperature and precipitation variables themselves explain more of the variance in species richness than the measured characteristics of species climatic niches.

Aim: To assess how habitat loss and climate change interact in affecting the range dynamics of species and to quantify how predicted range dynamics depend on demographic properties of species and the severity of environmental change. Location: South African Cape Floristic Region. Methods: We use data-driven demographic models to assess the impacts of past habitat loss and future climate change on range size, range filing and abundances of eight species of woody plants (Proteaceae). The species-specific models employ a hybrid approach that simulates population dynamics and long-distance dispersal on top of expected spatio-temporal dynamics of suitable habitat. Results: Climate change was mainly predicted to reduce range size and range filling (because of a combination of strong habitat shifts with low migration ability). In contrast, habitat loss mostly decreased mean local abundance. For most species and response measures, the combination of habitat loss and climate change had the most severe effect. Yet, this combined effect was mostly smaller than expected from adding or multiplying effects of the individual environmental drivers. This seems to be because climate change shifts suitable habitats to regions less affected by habitat loss. Interspecific variation in range size responses depended mostly on the severity of environmental change, whereas responses in range filling and local abundance depended mostly on demographic properties of species. While most surviving populations concentrated in areas that remain climatically suitable, refugia for multiple species were overestimated by simply overlying habitat models and ignoring demography. Main conclusions: Demographic models of range dynamics can simultaneously predict the response of range size, abundance and range filling to multiple drivers of environmental change. Demographic knowledge is particularly needed to predict abundance responses and to identify areas that can serve as biodiversity refugia under climate change. These findings highlight the need for data-driven, demographic assessments in conservation biogeography.