Extinction Vulnerability Research Articles

Quantifying the effects of Anthropocene activities on Mexican endemic amphibians

AbstractIn order to make robust and feasible conservation plans, assessments of species' vulnerability or risk of extinction are ideally needed. However, there are wide differences in the criteria used to assess species vulnerability. Recently, a growing approach seeks to understand the patterns of biodiversity loss using life history traits because these traits show differential responses to environmental disturbances. In order to generate a functional vulnerability assessment for Mexican endemic amphibians, we integrated information from species distribution modeling, functional traits, and spatially explicit threats weighted differentially for each functional group. We obtained 124 distribution models evaluated by species, nine functional groups that represent the differential risk of species against anthropic threats, and 124 layers of spatial vulnerability. We found a generalized presence of threats to amphibians throughout the Mexican territory, highlighting the center of the country as the most affected area, while the southeast and north had a lower level of anthropic activity. We found differential vulnerability values in the distributions of Mexican endemic amphibians. In general, the anthropogenic impact on the distribution of Mexican endemic amphibians is high, and the percentage of habitat loss ranges from 51 to 97%, with an average of 83% lost to anthropogenic pressures. The functional group with the greatest loss of distributional area was found in the salamander genus Ambystoma, while functional groups 2 (frogs with arboreal habits, small size, and reproduction and development in bodies of water) and 4 (small or medium size frogs occupying terrestrial or riparian habitats with oviposition and development occurring in bodies of water or phytotelms) maintain the largest remaining suitable area after considering the threats. We present a replicable methodology that can be implemented anywhere, providing a new tool to generate specific layers that represent threats to functional groups. This allows for updated assessments of species distribution models that can be used in conservation planning, offering more robust data to make conservation planning decisions.

Indigenous Peoples' Lands are critical for safeguarding vertebrate diversity across the tropics.

Indigenous Peoples are long-term custodians of their lands, but only recently are their contributions to conservation starting to be recognized in biodiversity policy and practice. Tropical forest loss and degradation are lower in Indigenous lands than unprotected areas, yet the role of Indigenous Peoples' Lands (IPL) in biodiversity conservation has not been properly assessed from regional to global scales. Using species distribution ranges of 11,872 tropical forest-dependent vertebrates to create area of habitat maps, we identified the overlap of these species ranges with IPL and then compared values inside and outside of IPL for species richness, extinction vulnerability, and range-size rarity. Of assessed vertebrates, at least 76.8% had range overlaps with IPL, on average overlapping ~25% of their ranges; at least 120 species were found only within IPL. Species richness within IPL was highest in South America, while IPL in Southeast Asia had highest extinction vulnerability, and IPL in Dominica and New Caledonia were important for range-size rarity. Most countries in the Americas had higher species richness within IPL than outside, whereas most countries in Asia had lower extinction vulnerability scores inside IPL and more countries in Africa and Asia had slightly higher range-size rarity in IPL. Our findings suggest that IPL provide critical support for tropical forest-dependent vertebrates, highlighting the need for greater inclusion of Indigenous Peoples in conservation target-setting and program implementation, and stronger upholding of Indigenous Peoples' rights in conservation policy.

Diversity, distribution and intrinsic extinction vulnerability of exploited marine bivalves

Marine bivalves are important components of ecosystems and exploited by humans for food across the world, but the intrinsic vulnerability of exploited bivalve species to global changes is poorly known. Here, we expand the list of shallow-marine bivalves known to be exploited worldwide, with 720 exploited bivalve species added beyond the 81 in the United Nations FAO Production Database, and investigate their diversity, distribution and extinction vulnerability using a metric based on ecological traits and evolutionary history. The added species shift the richness hotspot of exploited species from the northeast Atlantic to the west Pacific, with 55% of bivalve families being exploited, concentrated mostly in two major clades but all major body plans. We find that exploited species tend to be larger in size, occur in shallower waters, and have larger geographic and thermal ranges—the last two traits are known to confer extinction-resistance in marine bivalves. However, exploited bivalve species in certain regions such as the tropical east Atlantic and the temperate northeast and southeast Pacific, are among those with high intrinsic vulnerability and are a large fraction of regional faunal diversity. Our results pinpoint regional faunas and specific taxa of likely concern for management and conservation.

Immature feathers preserved in Burmite provide evidence of rapid molting in enantiornithines

Fossil feathers are recorded in the greatest fidelity in amber. A new specimen of Cenomanian aged Burmese amber provides the first unequivocal evidence of immature feathers in the Mesozoic fossil record. The small, clear piece, identified as aerial amber, preserves a cluster of body feathers with their basal portions encased in keratinous sheaths. The feathers are identified as belonging to a young enantiornithine individual based on the combination of preserved feather morphotypes, degree of feather asymmetry in the single preserved remix, their diminutive size, and because only enantiornithines have so far been recovered from these amber deposits. The body feathers are all at approximately the same stage of development suggesting that immature enantiornithines rapidly molted body feathers. This interpretation is supported by evidence from lithic specimens of juveniles from the Lower Cretaceous Jehol group that preserve immature feathers throughout the body. This specimen contributes to evidence that indicates enantiornithines hatched flight ready, with fully developed remiges, but with sparse body plumage that was simultaneously replaced during the prejuvenal molt. Rapid molts indicate periodic increases in thermostatic costs due to the temporary loss of insulation. This information leads to an intriguing new hypothesis regarding the extinction of Enantiornithes: that periods of increased thermostatic cost during early ontogeny created untenable energetic budgets during the asteroid induced impact winter, which resulted in both decreased global temperature and resource scarcity. High energetic budgets are associated with extinction vulnerability and may have been a major factor underpinning the extinction of this clade.

Dynamics of a spatially explicit eco-epidemic model with double Allee effect

This article deals with the dynamics of a reaction–diffusion eco-epidemic model that assimilates a double Allee effect. Allee effects are strongly related to extinction vulnerability of populations and two or more Allee effects can emerge simultaneously for the same population. Similarly, diseases can generate high mortality, decrease in reproduction rate, persistence, change in population size, etc. Surprisingly, relatively few studies capture the effect of both factors on a single population. Here we assume that susceptible prey populations suffer from both infectious and double Allee thresholds. We provide precise analysis of the proposed model, including (1) global existence of solutions; (2) the stability of positive constant solution; (3) sufficient conditions leading to Turing instabilities. We also conduct a thorough analysis of the associate local (ODE) system to enhance understanding of the effects of Allee and diffusion on the stability of the steady-state solution. The direction and stability of Hopf-bifurcation are analyzed for the local system concerning the Allee parameter. We have derived conditions for the occurrence of the overexploitation phenomenon, also demonstrated this through simulation. We emanate the pseudo-disease-free subsystem numerically with various dynamics related to the Allee threshold. Also this study shows that both Allee thresholds can generate chaotic dynamics. A brief simulation is performed to explain the developments of the pattern and its mechanism. Furthermore, we see that both weak and strong Allee effects can show enriched pattern diagrams.

Implications on the Use of the Phylogenetic Species Concept in the Risk Categories Assignment: The Case of the Birds of Mexico

Background and Aims Conservation efforts require a rational basis for taxa prioritization; it is essential to recognize the evolutionary independence of units, typically recognized as species. Because different criteria on species limits lead to different conservation assessment priorities, conceptual problems limit the possibility to accurately assess the conservation status that species are undergoing to protect them effectively. Methods We analyze the implications of using the phylogenetic species concept (PSC) in the risk categories determination, based on the analysis of the Mexican endemic avifauna. We modeled the potential distribution areas with the MaxEnt algorithm for those species that have had or could be susceptible to taxonomic updates based on the PSC. Results Of the 93 studied species, 68 were highly restricted, and 23 have high scores according to the evaluation of the Partners In Flight conservation status, so they can be considered species with high vulnerability or risk of extinction. Additionally, based on the recognition of several allopatric populations as independent phylogenetic species, 45% are susceptible to reconsideration of their risk categories due to a decrease in the extent of areas where they are potentially distributed. Implications for Conservation The use of a taxonomic perspective focused on the phylogenetic relationship of the different populations would directly impact the definition of risk categories, particularly for those endemic or restricted distribution evolutionary units for which there is usually very little information available and which, undoubtedly, are the ones that most need to be studied and, particularly, protected.

Genetic diversity of Malagasy baobabs: implications for conservation

Assessing the genetic diversity of species and populations is critical for evaluating extinction vulnerability and provides important information for identifying populations of concern and/or those that should be targeted for breeding material. Baobabs (Adansonia L.) are botanical icons for conservation, with increasing attention regarding their threatened status from both scientists and non-scientists alike. Baobabs are of particular interest especially in Madagascar, where six of the eight species are endemic, and three are listed as Endangered or Critically Endangered by the International Union for Conservation of Nature (IUCN). Although A. madagascariensis Baill., A. rubrostipa Jum. & H. Perrier and A. za Baill. are more widespread and classified by IUCN as Least Concern, they show regional variation, which may reflect hidden genetic diversity or even the existence of cryptic species. Here we assess the genetic diversity of the Malagasy baobabs to serve as a basis for future conservation and management planning. Our study used a targeted sequence capture approach (hybrid enrichment) to obtain hundreds of low-copy nuclear loci with phased alleles to assess genetic diversity in the six species and their major regional subpopulations. We discuss the implications of proper delineation of species taxonomy for management issues associated with conservation. We hope such genetic information will guide more targeted population genetic assessments and inform conservation and management efforts, including identification of isolated or disjunct populations that may warrant targeted actions.

Flora of Espírito Santo, Brazil: Alismataceae

Abstract This floristic survey of Alismataceae from the state of Espírito Santo aims to update the diversity and extinction vulnerability data for the species. The taxa here listed were obtained from Splink and Reflora Virtual Herbarium databases. A total of seven native taxa were registered for Espírito Santo state: Echinodorus grandiflorus, E. macrophyllus, Helanthium bolivianus, Hydrocleis nymphoides, Limnocharis flava, Sagittaria lancifolia and S. rhombifolia; the exotic species Alisma plantago-aquatica presented one single record. The populations occurred in flooded areas located at low altitudes and were primarily collected from some preserved areas and in the coastal region of the state. This study presents a taxonomic identification key, morphological descriptions and species illustrations. Comments on ecology, conservation and geographical distribution of the species are also presented.

Decreasing Phanerozoic extinction intensity as a consequence of Earth surface oxygenation and metazoan ecophysiology

The decline in background extinction rates of marine animals through geologic time is an established but unexplained feature of the Phanerozoic fossil record. There is also growing consensus that the ocean and atmosphere did not become oxygenated to near-modern levels until the mid-Paleozoic, coinciding with the onset of generally lower extinction rates. Physiological theory provides us with a possible causal link between these two observations-predicting that the synergistic impacts of oxygen and temperature on aerobic respiration would have made marine animals more vulnerable to ocean warming events during periods of limited surface oxygenation. Here, we evaluate the hypothesis that changes in surface oxygenation exerted a first-order control on extinction rates through the Phanerozoic using a combined Earth system and ecophysiological modeling approach. We find that although continental configuration, the efficiency of the biological carbon pump in the ocean, and initial climate state all impact the magnitude of modeled biodiversity loss across simulated warming events, atmospheric oxygen is the dominant predictor of extinction vulnerability, with metabolic habitat viability and global ecophysiotype extinction exhibiting inflection points around 40% of present atmospheric oxygen. Given this is the broad upper limit for estimates of early Paleozoic oxygen levels, our results are consistent with the relative frequency of high-magnitude extinction events (particularly those not included in the canonical big five mass extinctions) early in the Phanerozoic being a direct consequence of limited early Paleozoic oxygenation and temperature-dependent hypoxia responses.

Correlates of extinction vulnerability in Canadian’s prairie ecoregion

Correlates of extinction vulnerability in Canadian’s prairie ecoregion

Ecological correlates of extinction risk in Chinese terrestrial mammals

AbstractAimChina is among the countries with highest mammal diversity in the world, but a considerable proportion of Chinese terrestrial mammal species is currently at risk of extinction. For effective conservation, it would be fundamental to answer the following questions: (1) Is extinction risk randomly distributed among families in Chinese terrestrial mammals? (2) If not, which families are more threatened than expected by chance? (3) What are the major ecological predictors of extinction vulnerability? (4) Does taxonomic difference exist in ecological correlates of extinction risk? (5) To what extent does anthropogenic disturbance contribute to variations in extinction risk?LocationChina.MethodsWe collected data on biological traits, environmental factors and anthropogenic disturbance for 453 Chinese terrestrial mammals. We used phylogenetically controlled regression models and model selection to identify predictors of extinction risk for the whole species set and for the three large taxonomic groups (Carnivora, Artiodactyla and Lagomorpha) separately.ResultsWe found that extinction risk was not randomly distributed among families. Seven families (old world monkeys, gibbons, cats, civets and genets, musk deer, deer and bovids) contained significantly higher proportions of threatened species than expected by chance. Geographic range size was the only factor consistently supported in all the best models for the whole species set and for three large taxonomic groups. Although considered important in the global model for the whole species set, body weight was a poor predictor of extinction risk in taxon‐specific analyses. We also detected considerable differences in ecological correlates of extinction risk among Carnivora, Artiodactyla and Lagomorpha. After controlling for phylogeny, anthropogenic disturbance was not significantly correlated with extinction risk.Main conclusionsFor effective conservation, we should pay special attention to those highly threatened families and the species with limited range size. Our results also highlight the importance of performing taxon‐specific analyses for conservation practice.

Mapping shifts in spatial synchrony in grassland birds to inform conservation planning.

Spatial synchrony, defined as the correlated fluctuations in abundance of spatially separated populations, can be caused by regional fluctuations in natural and anthropogenic environmental population drivers. Investigations into the geography of synchrony can provide useful insight to inform conservation planning efforts by revealing regions of common population drivers and metapopulation extinction vulnerability. We examined the geography of spatial synchrony and decadal changes in these patterns for grassland birds in the United States and Canada, which are experiencing widespread and persistent population declines. We used Bayesian hierarchical models and over 50 years of abundance data from the North American Breeding Bird Survey to generate population indices within a 2° latitude by 2° longitude grid. We computed and mapped mean local spatial synchrony for each cell (mean detrended correlation of the index among neighboring cells), along with associated uncertainty, for 19 species in 2, 26-year periods, 1968-1993 and 1994-2019. Grassland birds were predicted to increase in spatial synchrony where agricultural intensification, climate change, or interactions between the 2 increased. We found no evidence of an overall increase in synchrony among grassland bird species. However, based on the geography of these changes, there was considerable spatial heterogeneity within species. Averaging across species, we identified clusters of increasing spatial synchrony in the Prairie Pothole and Shortgrass Prairie regions and a region of decreasing spatial synchrony in the eastern United States. Our approach has the potential to inform continental-scale conservation planning by adding an additional layer of relevant information to species status assessments and spatial prioritization of policy and management actions. Our work adds to a growing literature suggesting that global change may result in shifting patterns of spatial synchrony in population dynamics across taxa with broad implications for biodiversity conservation.

Treatment-induced evolutionary dynamics in nonmetastatic locally advanced rectal adenocarcinoma.

Multi-modal treatment of non-metastatic locally advanced rectal adenocarcinoma (LARC) includes chemotherapy, radiation, and life-altering surgery. Although highly effective for local cancer control, metastatic failure remains significant and drives rectal cancer-related mortality. A consistent observation of this tri-modality treatment paradigm is that histologic response of the primary tumor to neoadjuvant treatment(s), which varies across patients, predicts overall oncologic outcome. In this chapter, we will examine this treatment response heterogeneity in the context of evolutionary dynamics. We hypothesize that improved understanding of eco-evolutionary pressures rendering small cancer cell populations vulnerable to extinction may influence treatment strategies and improve patient outcomes. Applying effective treatment(s) to cancer populations causes a "race to extinction." We explore principles of eco-evolutionary extinction in the context of these small cancer cell populations, evaluating how treatment(s) aim to eradicate the cancer populations to ultimately result in cure. In this chapter, we provide an evolutionary rationale for limiting continuous treatment(s) with the same agent or combination of agents to avoid selection of resistant cancer subpopulation phenotypes, allowing "evolutionary rescue." We draw upon evidence from nature demonstrating species extinction rarely occurring as a single event phenomenon, but rather a series of events in the slide to extinction. We posit that eradicating small cancer populations, similar to small populations in natural extinctions, will usually require a sequence of different external perturbations that produce negative, synergistic dynamics termed the "extinction vortex." By exploiting these unique extinction vulnerabilities of small cancer populations, the optimal therapeutic sequences may be informed by evolution-informed strategies for patients with LARC.

Indirect terrestrial transmission of amphibian chytrid fungus from reservoir to susceptible host species leads to fatal chytridiomycosis

AbstractThe amphibian chytrid fungal pathogen (Batrachochytrium dendrobatidis, henceforth Bd) has had a devastating impact on biodiversity, causing the decline or extinction of over 500 amphibian species. Yet, our understanding of Bd transmission pathways remains incomplete, in particular for host species with weak aquatic associations, and between reservoir and susceptible host species. We examined Bd transmission from a potential reservoir host to a potentially susceptible critically endangered host; directly assessing the capacity of the former to transmit Bd, and the susceptibility of the latter as a Bd host. Using cohousing versus sequential use of the same enclosure by the two species, we distinguished the effects of direct versus indirect (environmental) transmission. Our study provides clear evidence that both direct and indirect terrestrial transmission from a reservoir to susceptible host species results in fatal chytridiomycosis. Transmission mode had no effect on overall morbidity or disease progression in the susceptible species. Our results demonstrate that reservoir and susceptible hosts do not need to be in the same place at the same time, or within an aquatic environment for transmission to occur. Our demonstration of indirect terrestrial transmission from a reservoir to susceptible host identifies mechanisms by which Bd may drive ongoing declines in populations where the pathogen is now endemic. Identifying these transmission pathways is important for understanding long‐term extinction vulnerability of remnant populations of declining species challenged by disease.

Reconciling Rubber Expansion with Biodiversity Conservation

Over five million hectares of tropical forest were cleared across mainland Southeast Asia and sub-Saharan Africa for rubber plantations between 2003 and 2017 [1, 2]. Millions of hectares of further clearance are predicted as rubber demand rises, which will have major consequences for biodiversity [3]. A key question is how to reconcile rubber expansion with biodiversity conservation. We assessed the feasibility of simultaneously meeting global future demand for rubber with conservation of extinction-threatened amphibians, birds, mammals, and reptiles. We compared the spatial congruence of rubber bioclimatic suitability with extinction vulnerability [4] in Africa, Asia, and New Guinea, where large-scale rubber cultivation is viable, and simulated rubber expansion under different scenarios. We found no "win-win" areas with highest rubber suitability and lowest extinction vulnerability. Projected rubber demand could be met by allowing expansion primarily in New Guinea and African Guinea. However, New Guinea has high ecosystem intactness and both regions are rich in endemics. Scenarios suggest converting only areas suitable for cultivation would cause the largest biodiversity losses, including endangered species, whereas prioritizing conservation would result in only the conversion of highly unsuitable land. Compromise scenarios that balance production with conservation could cut biodiversity losses by two-thirds, protecting most endangered species while maintaining high rubber suitability. Development of high-yielding hardy clones expands the amount of win-win areas, as well as suitable areas with high extinction risk. These trade-offs reveal that clonal research and development, strategic corporate and government land-use policies, and rigorous impact assessments are needed to prevent severe biodiversity losses from rubber development.

Incorporating coextinction in threat assessments and policy will rapidly improve the accuracy of threatened species lists

Threatened species lists are important policy tools for species conservation, and they are often used to help prioritize recovery actions. Current listing processes, such as the IUCN red list threat assessment, rely on accepted correlates of extinction risk, especially population size. Population size appears to be an effective indicator for threatened vertebrate species, but it is less relevant for invertebrate species, where population sizes are rarely known. Furthermore, many invertebrate species are dependent upon a host species for survival and reproduction, and thus host population sizes would be better indicators of (co-)extinction vulnerability. Improving listing criteria to be relevant to invertebrates is important, because faunal biodiversity consists predominantly of invertebrate species (>98%) and invertebrates likely represent a majority of the current global sixth mass extinction event. Here, we propose including the degree of host specificity of a dependent invertebrate species to threatened host species as an additional correlate of extinction proneness, where there is a continuum from generalist dependents to dependents that are completely specialized to use a single host species per life stage. For highly specialized dependent taxa, we recommend that that threat category assigned to the dependent species should match the threat category assigned to the host species. Incorporating this correlate of extinction risk into threatened species policy, such as the IUCN red list, could rapidly increase the rate of assessments for many invertebrates and justify their inclusion, where previously they may have been considered data deficient.

Impact of 2019-2020 mega-fires on Australian fauna habitat.

Australia's 2019-2020 mega-fires were exacerbated by drought, anthropogenic climate change and existing land-use management. Here, using a combination of remotely sensed data and species distribution models, we found these fires burnt ~97,000 km2 of vegetation across southern and eastern Australia, which is considered habitat for 832 species of native vertebrate fauna. Seventy taxa had a substantial proportion (>30%) of habitat impacted; 21 of these were already listed as threatened with extinction. To avoid further species declines, Australia must urgently reassess the extinction vulnerability of fire-impacted species and assist the recovery of populations in both burnt and unburnt areas. Population recovery requires multipronged strategies aimed at ameliorating current and fire-induced threats, including proactively protecting unburnt habitats.

Widespread low abundance despite habitat availability elevates extinction risk in pygmy seahorses

Due to difficulties with surveying, cryptobenthic fishes are understudied, which limits assessments of their extinction risk. Using a novel survey method (a combination of underwater visual census and underwater biofluorescence census), we surveyed the densities of two gorgonian seafan-associated pygmy seahorses (Hippocampus bargibanti and H. denise) in 63 sites across Indonesia. Densities were low for both seahorses (≤ 0.4 seahorses/host) and their hosts (≤ 0.25 seafans/200 m2). These low densities, combined with habitat specialisation, increase extinction risk. We failed to detect regional or depth patterns in seahorse abundance per host or group size in occupied hosts. Host occupancy rates were low (< 13.7%), suggesting that other factors than habitat availability constrain pygmy seahorse population size. The low densities found in this study highlight the high extinction vulnerability for habitat specialists on coral reefs.

Urban effluents affect the early development stages of Brazilian fish species with implications for their population dynamics.

The pollution from urban effluents discharged into natural waters is a major cause of aquatic biodiversity loss. Ecotoxicological testing contributes significantly to understand the risk of exposure to the biota and to establish conservation policies. The objective of the current study was to assess the toxicity of a river highly influenced by urban effluents (Atuba River, Curitiba city, Southern Brazil) to the early stages of development in four South American native fish species, investigating the consequences at the population level through mathematical modelling. The species chosen were Salminus brasiliensis, Prochilodus lineatus, Rhamdia quelen, and Pseudoplatystoma corruscans, ecologically important species encompassing different conservation statuses and vulnerability. The embryos were exposed from 8 to 96 h post fertilization to the Atuba River water, collected downstream of the largest wastewater treatment plant in the Metropolitan Region of Curitiba, and their survival rates and deformities were registered. The species S. brasiliensis and P. lineatus presented the highest mortality rates, showing high sensitivity to the pollutants present in the water. According to the individual-based mathematical model, these species showed high vulnerability and risk of extinction under the tested experimental conditions, even when different sensitivity scenarios of juveniles and adults were considered. The other two species, R. quelen and P. corruscans, showed a more resistant condition to mortality, but also presented high frequency and severity of deformities. These results emphasize the importance of testing the sensitivity of different Brazilian native species for the conservation of biodiversity and the application of models to predict the effects of pollutants at the population level.

Constraints on vertebrate range size predict extinction risk

AbstractAimThe only factor in the fossil record that consistently buffers against extinction risk is large geographical range. We ask whether extant vertebrate species with the smallest geographical range for their body size have a higher extinction risk, and thus whether the lower bound of the modern range–body size relationship could serve as an effective conservation prioritization tool.LocationGlobal in scope.Time periodModern.Major taxa studiedSix classes of vertebrates.MethodsWe compiled a database of geographical range, body size and extinction risk for six vertebrate classes (n = 26,076). We characterized the shape of the relationship between geographical range and body size for each class, using 90% and 10% quantile regression to describe the upper and lower bounds, respectively. We then evaluated the degree of extinction vulnerability of species at the lower bound of the regression using generalized linear mixed models. All analyses accounted for phylogenetic dependence between related species.ResultsThe relationships between species ranges and body sizes were generally positive at both the upper and the lower bounds, and segmented (nonlinear) relationships were common. Despite this variability, species near the lower boundary of the relationship were more often in higher extinction risk categories, and this remained true when the role of range size in the International Union for Conservation of Nature Red Listing criteria was accounted for.Main conclusionsVariability in the upper and lower bounds of the range–body size relationship suggests that some classes of vertebrates exhibit combinations of ranges and body sizes that might not reflect historical patterns. Nonetheless, the range–body size relationship remains a reliable and useful predictor of extinction risk, more so than range size does alone. The range–body size relationship could therefore be used to track the trajectories of species towards or away from an extinction threshold and allow the tracking of how different human activities alter the range–body size relationship.