Latent extinction risk and the future battlegrounds of mammal conservation

Niche-based approach to explore the impacts of environmental disturbances on biodiversity

Globally, species are increasingly at risk from compounding threatening processes, an increasingly prominent driver of which is environmental disturbances. To facilitate effective conservation efforts following such events, methods that evaluate potential impacts across multiple species and provide landscape-scale information are needed to guide targeted responses. Often, the geographic overlap between a disturbance and species' distribution is calculated and then used as a proxy for potential impact. However, such methods do not account for the important influence of environmental heterogeneity throughout species' ranges. To address this shortcoming, we quantified the effects of environmental disturbances on species' environmental niche space. Using the Australian 2019 and 2020 Black Summer fires as a case study, we applied a niche-centric approach to examine the potential impacts of these fires on 387 vertebrate species. We examined the utility of established and novel niche metrics to assess the potential impacts of large-scale disturbance events on species by comparing the potential effects of the fires as determined by our various niche measures to those derived from geographic-based measures of impact. We examined the quality of environmental space affected by the disturbance by quantifying the position in niche space where the disturbance occurred (center or margin), the uniqueness of the environmental space that was burned, and the degree to which the remaining, unburned portion of the niche differed from a species' original prefire niche. There was limited congruence between the proportion of geographic and niche space affected, which showed that geographic-based approaches in isolation may have underestimated the impact of the fires for 56% of modeled species. For each species, when combined, these metrics provided a greater indication of postdisturbance recovery potential than geographic-based measures alone. Accordingly, the integration of niche-based analyses into conservation assessments following large-scale disturbance events will lead to a more nuanced understanding of potential impacts and guide more informed and effective conservation actions.

Phylogenetic, morphological and niche differentiation unveil new species limits for the big brown bat (Eptesicus fuscus)

Phylogeographic accounts of mammals across fragmented landscapes show high levels of genetic, morphological and ecological variation. The big brown bat (Eptesicus fuscus) widely spans mainland landmasses from Canada to Ecuador and Colombia, and the insular Caribbean through The Bahamas and Greater and Lesser Antilles. Given the distribution of E. fuscus, we hypothesized that insular lineages could represent a different species aided by isolation. We assessed species limits by capitalizing on available mitochondrial and genomic data. Novel morphological and spatial datasets were produced to examine limits phenotypically and whether ecological niches could be associated with differences between groups. Phylogenetics strongly supported the Caribbean as unique compared to the mainland. Genomic data indicated high levels of genetic structure within the Caribbean and no detectable admixture of the Caribbean with continental lineages. Similarly, the Caribbean group shows high phenotypic disparity, and niche models revealed differences in habitat suitability between groups, concordant with the phylogenetic results. This study uncovered signals of divergence supporting the Caribbean clade of E. fuscus as unique through an integrative framework. We endorse re-evaluating the taxonomic status of Caribbean big brown bats as Eptesicus dutertreus. This recognition can help promote local conservation plans for insular lineages of big brown bats.

Biodiversity conservation: Looking over the horizon

In an age of planetary changes, conservation efforts are essential to protect biodiversity and nature's benefits to people. Large-scale quantitative analyses forecasting major threats to biodiversity can provide insights into which species and areas should be prioritised for conservation.

Priorities for conserving the world's terrestrial mammals based on over-the-horizon extinction risk

Three major axes of global change put the world's mammal biodiversity at risk: climate change, human population growth, and land-use change.^{1,2,3,4,5,6,7,8,9,10,11,12} In some parts of the world the full effects of these threats on species will only be felt in decades to come, yet conservation emphasizes species currently threatened with extinction, by threats that have already occurred. There have been calls for conservation to become more proactive by anticipating and protecting species that may not yet be threatened, but have a high chance of becoming threatened in the future.^{3,6,8,10,12,13,14} We refer to this as "over-the-horizon" extinction risk, and we identify such species among the world's nonmarine mammals by considering not only the severity of increase in threats faced by each species, but also the way each species' biology confers sensitivity or robustness to threats. We define four future risk factors based on species' biology and projected exposure to severe change in climate, human population, and land use. We regard species with two or more of these risk factors as especially vulnerable to future extinction risk.^{10,15,16,17,18,19} Our models predict that by 2100 up to 1,057 (20%) of nonmarine mammal species will have combinations of two or more future risk factors. These species will be particularly concentrated in two future risk hotspots in sub-Saharan Africa and southern/eastern Australia. Proactively targeting species with over-the-horizon extinction risk could help to future-proof global conservation planning and prevent a new wave of mammal species from becoming threatened with extinction by the end of this century.

Digging in a 120 years-old lunch: What can we learn from collection specimens of extinct species?

Studying collection specimens is often the only way to unravel information about recent extinctions. These can reveal knowledge on threats and life traits related to extinction, and contribute, by extrapolation, to the conservation of extant species. However, high-throughput sequencing methods have rarely been applied to extinct species to reveal information on their ecology. Insular species are especially prone to extinction. We studied the gut contents of three specimens of the extinct giant skink Chioninia coctei of the Cabo Verde Islands using microscopy and DNA-metabarcoding. The presence of Tachygonetria adult nematodes suggests plants as important diet items. Our metabarcoding approach also identified plants and, additionally, invertebrates, supporting the hypothesis of C. coctei’s generalist diet. The absence of vertebrates in the digestive contents may reflect the decline of seabirds on the Desertas Islands that could have contributed to the debilitation of the giant skink, already depleted by persecution and severe droughts. Even with a small sample size, this study contributes to shedding light on the trophic roles of this enigmatic extinct species and emphasizes the need to develop holistic conservation plans for island threatened taxa. Additionally, it illustrates the potential of integrating up-to-date molecular methods with traditional approaches to studying collection specimens to help to solve ecological puzzles in other ecosystems.

The efficacy of interventions to protect crops from raiding elephants

Both African elephants (Loxodonta spp.) and the Asian elephant (Elephas maximus) across their range come into conflict with people because of their crop-raiding behavior, which presents profound impediments to farmer livelihoods. In response, a series of interventions, designed to reduce elephant crop raiding have been applied. Based on an extensive review of elephant crop-raiding studies published over a 31-year period, we identified four primary categories of interventions including: (i) detection efforts; (ii) preemptive measures; (iii) fencing and trenches; and (iv) deterrent techniques. The interventions reported to be most effective involved chili peppers (i.e., fences, spray, and briquettes) and crop guarding coupled with deterrents. The extent to which these interventions can be applied more widely is unclear as only two studies examined efficacy across sites in more than one country. Thus, future inquiry should evaluate the ability of effective interventions, or indeed a combination of interventions, to be applied across the range of elephants to reduce crop raiding at scale.

Diversity and extinction risk are inversely related at a global scale

Increases in biodiversity often lead to greater, and less variable, levels of ecosystem functioning. However, whether species are less likely to go extinct in more diverse ecosystems is unclear. We use comprehensive estimates of avian taxonomic, phylogenetic and functional diversity to characterise the global relationship between multiple dimensions of diversity and extinction risk in birds, focusing on contemporary threat status and latent extinction risk. We find that more diverse assemblages have lower mean IUCN threat status despite being composed of species with attributes that make them more vulnerable to extinction, such as large body size or small range size. Indeed, the reduction in current threat status associated with greater diversity far outweighs the increased risk associated with the accumulation of extinction‐prone species in more diverse assemblages. Our results suggest that high diversity reduces extinction risk, and that species conservation targets may therefore best be achieved by maintaining high levels of overall biodiversity in natural ecosystems.

Global predictors of language endangerment and the future of linguistic diversity

Language diversity is under threat. While each language is subject to specific social, demographic and political pressures, there may also be common threatening processes. We use an analysis of 6,511 spoken languages with 51 predictor variables spanning aspects of population, documentation, legal recognition, education policy, socioeconomic indicators and environmental features to show that, counter to common perception, contact with other languages per se is not a driver of language loss. However, greater road density, which may encourage population movement, is associated with increased endangerment. Higher average years of schooling is also associated with greater endangerment, evidence that formal education can contribute to loss of language diversity. Without intervention, language loss could triple within 40 years, with at least one language lost per month. To avoid the loss of over 1,500 languages by the end of the century, urgent investment is needed in language documentation, bilingual education programmes and other community-based programmes.

Scientists' warning - The outstanding biodiversity of islands is in peril

Despite islands contributing only 6.7% of land surface area, they harbor ~20% of the Earth’s biodiversity, but unfortunately also ~50% of the threatened species and 75% of the known extinctions since the European expansion around the globe. Due to their geological and geographic history and characteristics, islands act simultaneously as cradles of evolutionary diversity and museums of formerly widespread lineages—elements that permit islands to achieve an outstanding endemicity. Nevertheless, the majority of these endemic species are inherently vulnerable due to genetic and demographic factors linked with the way islands are colonized. Here, we stress the great variation of islands in their physical geography (area, isolation, altitude, latitude) and history (age, human colonization, human density). We provide examples of some of the most species rich and iconic insular radiations. Next, we analyze the natural vulnerability of the insular biota, linked to genetic and demographic factors as a result of founder events as well as the typically small population sizes of many island species. We note that, whereas evolution toward island syndromes (including size shifts, derived insular woodiness, altered dispersal ability, loss of defense traits, reduction in clutch size) might have improved the ability of species to thrive under natural conditions on islands, it has simultaneously made island biota disproportionately vulnerable to anthropogenic pressures such as habitat loss, overexploitation, invasive species, and climate change. This has led to the documented extinction of at least 800 insular species in the past 500 years, in addition to the many that had already gone extinct following the arrival of first human colonists on islands in prehistoric times. Finally, we summarize current scientific knowledge on the ongoing biodiversity loss on islands worldwide and express our serious concern that the current trajectory will continue to decimate the unique and irreplaceable natural heritage of the world’s islands. We conclude that drastic actions are urgently needed to bend the curve of the alarming rates of island biodiversity loss.

The ghost of hosts past: impacts of host extinction on parasite specificity

A growing body of research is focused on the extinction of parasite species in response to host endangerment and declines. Beyond the loss of parasite species richness, host extinction can impact apparent parasite host specificity, as measured by host richness or the phylogenetic distances among hosts. Such impacts on the distribution of parasites across the host phylogeny can have knock-on effects that may reshape the adaptation of both hosts and parasites, ultimately shifting the evolutionary landscape underlying the potential for emergence and the evolution of virulence across hosts. Here, we examine how the reshaping of host phylogenies through extinction may impact the host specificity of parasites, and offer examples from historical extinctions, present-day endangerment, and future projections of biodiversity loss. We suggest that an improved understanding of the impact of host extinction on contemporary host-parasite interactions may shed light on core aspects of disease ecology, including comparative studies of host specificity, virulence evolution in multi-host parasite systems, and future trajectories for host and parasite biodiversity. This article is part of the theme issue 'Infectious disease macroecology: parasite diversity and dynamics across the globe'.

Chromosome-Level Reference Genome Assembly for the American Pika (Ochotona princeps)

The American pika (Ochotona princeps) is an alpine lagomorph found throughout western North America. Primarily inhabiting talus slopes at higher elevations (>2000 m), American pikas are well adapted to cold, montane environments. Warming climates on both historical and contemporary scales have contributed to population declines in American pikas, positioning them as a focal mammalian species for investigating the ecological effects of climate change. To support and expand ongoing research efforts, here, we present a highly contiguous and annotated reference genome assembly for the American pika (OchPri4.0). This assembly was produced using Dovetail de novo proximity ligation methods and annotated through the NCBI Eukaryotic Genome Annotation pipeline. The resulting assembly was chromosome- scale, with a total length of 2.23 Gb across 9350 scaffolds and a scaffold N50 of 75.8 Mb. The vast majority (>97%) of the total assembly length was found within 36 large scaffolds; 33 of these scaffolds correlated to whole autosomes, while the X chromosome was covered by 3 large scaffolds. Additionally, we identified 17 enriched gene ontology terms among American pika-specific genes putatively related to adaptation to high-elevation environments. This high-quality genome assembly will serve as a springboard for exploring the evolutionary underpinnings of behavioral, ecological, and taxonomic diversification in pikas as well as broader-scale eco-evolutionary questions pertaining to cold-adapted species in general.

Scale-dependent effects of niche specialisation: The disconnect between individual and species ranges

One of the most general expectations of species range dynamics is that widespread species tend to have broader niches. However, it remains unclear how this relationship is expressed at different levels of biological organisation, which involve potentially distinctive processes operating at different spatial and temporal scales. Here, we show that range sizes of terrestrial non-volant mammals at the individual and species level show contrasting relationships with two ecological niche dimensions: diet and habitat breadth. While average individual home range size appears to be mainly shaped by the interplay of diet niche breadth and body mass, species geographical range size is primarily related to habitat niche breadth but not to diet niche breadth. Our findings suggest that individual home range size is shaped by the trade-off between energetic requirements, movement capacity and trophic specialisation, whereas species geographical range size is related to the ability to persist under various environmental conditions.

Intact forests of the Hkakabo Razi Landscape are a hotspot of bat diversity in South-east Asia

The Hkakabo Razi Landscape, in northern Kachin, Myanmar, is one of the largest remaining tracts of intact forest in South-east Asia. In 2016, we undertook a survey in its southern margins to assess bat diversity, distribution and ecology and evaluate the importance of the area for global bat conservation. Two collecting trips had taken place in the area in 1931 and 1933, with four bat species reported. We recorded 35 species, 18 of which are new for Kachin. One species, Murina hkakaboraziensis, was new to science and three, Megaerops niphanae, Phoniscus jagorii, Murina pluvialis, were new records for Myanmar. Our findings indicate high bat diversity in Hkakabo Razi; although it comprises only 1.7% of Myanmar's land area, it is home to 33.6% of its known bat species. This emphasizes Hkakabo Razi's importance for conserving increasingly threatened, forest-interior bats, especially in the families Kerivoulinae and Murininae. There is also a high diversity of other mammals and birds within the Hkakabo Razi Landscape, which supports its nomination as a World Heritage Site.

Clarifying the relationship between body size and extinction risk in amphibians by complete mapping of model space

In vertebrates, large body size is often a key diagnostic feature of species threatened with extinction. However, in amphibians the link between body size and extinction risk is highly uncertain, with previous studies suggesting positive, negative, u-shaped, or no relationship. Part of the reason for this uncertainty is 'researcher degrees of freedom': the subjectivity and selectivity in choices associated with specifying and fitting models. Here, I clarify the size-threat association in amphibians using Specification Curve Analysis, an analytical approach from the social sciences that attempts to minimize this problem by complete mapping of model space. I find strong support for prevailing negative associations between body size and threat status, the opposite of patterns typical in other vertebrates. This pattern is largely explained by smaller species having smaller geographic ranges, but smaller amphibian species also appear to lack some of the life-history advantages (e.g. higher reproductive output) that are often assumed to 'protect' small species in other taxa. These results highlight the need for a renewed conservation focus on the smallest species of the world's most threatened class of vertebrates, as aquatic habitats become increasingly degraded by human activity.

Incorporating Biological Traits into Conservation Strategies

Implementation of marine conservation strategies, such as increasing the numbers, extent, and effectiveness of protected areas (PAs), can help achieve conservation and restoration of ocean health and associated goods and services. Despite increasing recognition of the importance of including aspects of ecological functioning in PA design, the physical characteristics of habitats and simple measures of species diversity inform most PA designations. Marine and terrestrial ecologists have recently been using biological traits to assess community dynamics, functioning, and vulnerability to anthropogenic impacts. Here, we explore potential trait-based marine applications to advance PA design. We recommend strategies to integrate biological traits into (a) conservation objectives (e.g., by assessing and predicting impacts and vulnerability), (b) PA spatial planning (e.g., mapping ecosystem functions and functional diversity hot spots), and (c) time series monitoring protocols (e.g., using functional traits to detect recoveries). We conclude by emphasizing the need for pragmatic tools to improve the efficacy of spatial planning and monitoring efforts.

Integrating camera traps and community knowledge to assess the status of the Indian pangolin Manis crassicaudata in the Eastern Ghats, India

Pangolins are the most trafficked animals globally. Although the Indian pangolin Manis crassicaudata occurs across the Indian subcontinent (excluding parts of the Himalayas and the north-east, where the Chinese pangolin Manis pentadactyla is present), it is categorized as Endangered on the IUCN Red List as a result of heavy poaching for its meat and scales. Several areas have not yet been surveyed for the occurrence of the Indian pangolin, one of which is the 16,948 km2 tropical deciduous forests of the northern Eastern Ghats landscape in Andhra Pradesh. During December 2017–April 2018, we surveyed 750 km2 of this landscape for the presence of the Indian pangolin, using camera traps. As an alternative method to document pangolin presence, and to identify factors driving hunting of the species, we also conducted, during the same period, a total of 60 semi-structured interviews with people in 30 villages. Interviewees reported the presence of pangolins in a majority of the grid cells that we surveyed with camera traps, particularly in moist deciduous forests distant from villages. However, the camera traps did not detect pangolins in 840 trap-days. Hunting of pangolins for their meat, which is consumed locally, and for their scales, which are traded, is most likely the reason for the rarity of the species in this landscape. A better understanding of the proximate and ultimate drivers of pangolin hunting is required, to inform proactive conservation management for this increasingly threatened species.

Spatiophylogenetic modelling of extinction risk reveals evolutionary distinctiveness and brief flowering period as threats in a hotspot plant genus

Comparative models used to predict species threat status can help identify the diagnostic features of species at risk. Such models often combine variables measured at the species level with spatial variables, causing multiple statistical challenges, including phylogenetic and spatial non-independence. We present a novel Bayesian approach for modelling threat status that simultaneously deals with both forms of non-independence and estimates their relative contribution, and we apply the approach to modelling threat status in the Australian plant genus Hakea. We find that after phylogenetic and spatial effects are accounted for, species with greater evolutionary distinctiveness and a shorter annual flowering period are more likely to be threatened. The model allows us to combine information on evolutionary history, species biology and spatial data, calculate latent extinction risk (potential for non-threatened species to become threatened), estimate the most important drivers of risk for individual species and map spatial patterns in the effects of different predictors on extinction risk. This could be of value for proactive conservation decision-making based on the early identification of species and regions of potential conservation concern.

Fear and stressing in predator-prey ecology: considering the twin stressors of predators and people on mammals

Predators induce stress in prey and can have beneficial effects in ecosystems, but can also have negative effects on biodiversity if they are overabundant or have been introduced. The growth of human populations is, at the same time, causing degradation of natural habitats and increasing interaction rates of humans with wildlife, such that conservation management routinely considers the effects of human disturbance as tantamount to or surpassing those of predators. The need to simultaneously manage both of these threats is particularly acute in urban areas that are, increasingly, being recognized as global hotspots of wildlife activity. Pressures from altered predator-prey interactions and human activity may each initiate fear responses in prey species above those that are triggered by natural stressors in ecosystems. If fear responses are experienced by prey at elevated levels, on top of responses to multiple environmental stressors, chronic stress impacts may occur. Despite common knowledge of the negative effects of stress, however, it is rare that stress management is considered in conservation, except in intensive ex situ situations such as in captive breeding facilities or zoos. We propose that mitigation of stress impacts on wildlife is crucial for preserving biodiversity, especially as the value of habitats within urban areas increases. As such, we highlight the need for future studies to consider fear and stress in predator-prey ecology to preserve both biodiversity and ecosystem functioning, especially in areas where human disturbance occurs. We suggest, in particular, that non-invasive in situ investigations of endocrinology and ethology be partnered in conservation planning with surveys of habitat resources to incorporate and reduce the effects of fear and stress on wildlife.

Application of multiple-population viability analysis to evaluate species recovery alternatives

Population viability analysis (PVA) is a powerful conservation tool, but it remains impractical for many species, particularly species with multiple, broadly distributed populations for which collecting suitable data can be challenging. A recently developed method of multiple-population viability analysis (MPVA), however, addresses many limitations of traditional PVA. We built on previous development of MPVA for Lahontan cutthroat trout (LCT) (Oncorhynchus clarkii henshawi), a species listed under the U.S. Endangered Species Act, that is distributed broadly across habitat fragments in the Great Basin (U.S.A.). We simulated potential management scenarios and assessed their effects on population sizes and extinction risks in 211 streams, where LCT exist or may be reintroduced. Conservation populations (those managed for recovery) tended to have lower extinction risks than nonconservation populations (mean = 19.8% vs. 52.7%), but not always. Active management or reprioritization may be warranted in some cases. Eliminating non-native trout had a strong positive effect on overall carrying capacities for LCT populations but often did not translate into lower extinction risks unless simulations also reduced associated stochasticity (to the mean for populations without non-native trout). Sixty fish or 5-10 fish/km was the minimum reintroduction number and density, respectively, that provided near-maximum reintroduction success. This modeling framework provided crucial insights and empirical justification for conservation planning and specific adaptive management actions for this threatened species. More broadly, MPVA is applicable to a wide range of species exhibiting geographic rarity and limited availability of abundance data and greatly extends the potential use of empirical PVA for conservation assessment and planning.

Global change biology: A primer

Because of human action, the Earth has entered an era where profound changes in the global environment are creating novel conditions that will be discernable far into the future. One consequence may be a large reduction of the Earth's biodiversity, potentially representing a sixth mass extinction. With effective stewardship, the global change drivers that threaten the Earth's biota could be alleviated, but this requires clear understanding of the drivers, their interactions, and how they impact ecological communities. This review identifies 10 anthropogenic global change drivers and discusses how six of the drivers (atmospheric CO₂ enrichment, climate change, land transformation, species exploitation, exotic species invasions, eutrophication) impact Earth's biodiversity. Driver impacts on a particular species could be positive or negative. In either case, they initiate secondary responses that cascade along ecological lines of connection and in doing so magnify the initial impact. The unique nature of the threat to the Earth's biodiversity is not simply due to the magnitude of each driver, but due to the speed of change, the novelty of the drivers, and their interactions. Emphasizing one driver, notably climate change, is problematic because the other global change drivers also degrade biodiversity and together threaten the stability of the biosphere. As the main academic journal addressing global change effects on living systems, GCB is well positioned to provide leadership in solving the global change challenge. If humanity cannot meet the challenge, then GCB is positioned to serve as a leading chronicle of the sixth mass extinction to occur on planet Earth.

The dynamics underlying avian extinction trajectories forecast a wave of extinctions

Population decline is a process, yet estimates of current extinction rates often consider just the final step of that process by counting numbers of species lost in historical times. This neglects the increased extinction risk that affects a large proportion of species, and consequently underestimates the effective extinction rate. Here, we model observed trajectories through IUCN Red List extinction risk categories for all bird species globally over 28 years, and estimate an overall effective extinction rate of 2.17 × 10^-4/species/year. This is six times higher than the rate of outright extinction since 1500, as a consequence of the large number of species whose status is deteriorating. We very conservatively estimate that global conservation efforts have reduced the effective extinction rate by 40%, but mostly through preventing critically endangered species from going extinct rather than by preventing species at low risk from moving into higher-risk categories. Our findings suggest that extinction risk in birds is accumulating much more than previously appreciated, but would be even greater without conservation efforts.

Conservation Genomics in a Changing Arctic

Although logistically challenging to study, the Arctic is a bellwether for global change and is becoming a model for questions pertinent to the persistence of biodiversity. Disruption of Arctic ecosystems is accelerating, with impacts ranging from mixing of biotic communities to individual behavioral responses. Understanding these changes is crucial for conservation and sustainable economic development. Genomic approaches are providing transformative insights into biotic responses to environmental change, but have seen limited application in the Arctic due to a series of limitations. To meet the promise of genome analyses, we urge rigorous development of biorepositories from high latitudes to provide essential libraries to improve the conservation, monitoring, and management of Arctic ecosystems through genomic approaches.

Integrating behaviour and ecology into global biodiversity conservation strategies

Insights into animal behaviour play an increasingly central role in species-focused conservation practice. However, progress towards incorporating behaviour into regional or global conservation strategies has been more limited, not least because standardized datasets of behavioural traits are generally lacking at wider taxonomic or spatial scales. Here we make use of the recent expansion of global datasets for birds to assess the prospects for including behavioural traits in systematic conservation priority-setting and monitoring programmes. Using International Union for Conservation of Nature Red List classifications for more than 9500 bird species, we show that the incidence of threat can vary substantially across different behavioural categories, and that some types of behaviour-including particular foraging, mating and migration strategies-are significantly more threatened than others. The link between behavioural traits and extinction risk is partly driven by correlations with well-established geographical and ecological factors (e.g. range size, body mass, human population pressure), but our models also reveal that behaviour modifies the effect of these factors, helping to explain broad-scale patterns of extinction risk. Overall, these results suggest that a multi-species approach at the scale of communities, continents and ecosystems can be used to identify and monitor threatened behaviours, and to flag up cases of latent extinction risk, where threatened status may currently be underestimated. Our findings also highlight the importance of comprehensive standardized descriptive data for ecological and behavioural traits, and point the way towards deeper integration of behaviour into quantitative conservation assessments. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

Deciphering forest change: Linking satellite-based forest cover change and community perceptions in a threatened landscape in India

Global conservation efforts have traditionally focused on biodiversity hotspots and other priority landscapes. However, large areas outside priority sites have high conservation value and are referred to as neglected landscapes. The Eastern Ghats of India is an unexplored forest landscape of high conservation value with several endemic and threatened species reported, and is also home to many indigenous forest-dwelling communities. However, it remains a neglected area for conservation and only 3.53% of this landscape is protected. Here, we examine the effectiveness of protected areas in neglected landscapes in preventing forest degradation, and how community perceptions can be used to understand satellite-based landscape change analyses at village level. This study was conducted in Papikonda National park (PNP) and its unprotected buffers in India's Eastern Ghats. Forest degradation was higher in the buffer (32%) than inside PNP (12%) between 1991 and 2014. Communities attributed shifting cultivation, plantations and over-extraction of forest resources as being the major drivers of forest degradation. Community observations of change were not significantly correlated with spatial measures of change. Forest degradation was higher outside the PA at a landscape level and inside the PA at the village level, therefore the PA was effective in reducing degradation at the landscape level but not at the village level inside the PA. We further discuss the role of community observations in interpreting forest degradation in neglected forest landscapes.

Species characteristics affect local extinctions

PREMISE OF THE STUDY

Human activities threaten thousands of species with extinction. However, it remains difficult to predict extinction risk for many vulnerable species. Species traits, species characteristics such as rarity or habitat use, and phylogenetic patterns are associated with responses to anthropogenic environmental change and may help predict likelihood of extinction.

METHODS

We used historical botanical data from Kalamazoo County, Michigan, USA, to examine whether species traits (growth form, life history, nitrogen-fixation, photosynthetic pathway), species characteristics (community association, species origin, range edge, habitat specialization, rarity), or phylogenetic relatedness explain local species loss at the county level.

KEY RESULTS

Across Kalamazoo County, prairie species, species at the edge of their native range, regionally rare species, and habitat specialists were most likely to become locally extinct. Prairie species experienced the highest local extinction rates of any habitat type, and among prairie species, regionally rare and specialist species were most vulnerable to loss. We found no evidence for a phylogenetic pattern in plant extinctions.

CONCLUSIONS

Our study illustrates the value of historical datasets for understanding and potentially predicting biodiversity loss. Not surprisingly, rare, specialist species occupying threatened habitats are most at risk of local extinction. As a result, identifying mechanisms to conserve or restore rare or declining species and preventing further habitat destruction may be the most effective strategies for reducing future extinction.

Minimum viable population size and population growth rate of freshwater fishes and their relationships with life history traits

The minimum viable population (MVP) size has been compared for a wide range of organisms in conservation biology, but a limited number of studies investigated it for freshwater fishes, which exhibit diverse life history strategies. In this study, the MVP size and population growth rate of 36 fish species in the Yangtze River were estimated and compared with their life-history traits. The results indicated that the MVP size ranged from 42 to 320 individuals, and instantaneous per-capita population growth rate ranged from 0.009 to 0.188 per year. MVP size and population growth rate were significantly associated with three life history traits: the age at maturity, generation time, and fecundity. Long-lived species with delayed maturation, long generation time, and high fecundity had a greater MVP size and a lower population growth rate than short-lived species. Therefore, our results emphasize a need for prioritizing our conservation effort more on long-lived species.

Mammal extinctions and the increasing isolation of humans on the tree of life

A sixth great mass extinction is ongoing due to the direct and indirect effects of human pressures. However, not all lineages are affected equally. From an anthropocentric perspective, it is often purported that humans hold a unique place on Earth. Here, we show that our current impacts on the natural world risk realizing that expectation. We simulated species loss on the mammalian phylogenetic tree, informed by species current extinction risks. We explored how Homo sapiens could become isolated in the tree if species currently threatened with extinction disappeared. We analyzed correlates of mammal extinctions risks that may drive this isolation pattern. We show that, within mammals, and more particularly within primates, extinction risks increase with the number of known threat types, and decrease with geographic range size. Extinctions increase with species body mass, trophic level, and the median longitudinal extent of each species range in mammals but not within primates. The risks of extinction are frequently high among H. sapiens close relatives. Pruning threatened primates, including apes (Hominidae, Hylobatidae), from the tree of life will lead to our species being among those with the fewest close relatives. If no action is taken, we will thus not only lose crucial biodiversity for the preservation of Earth ecosystems, but also a key living reference to what makes us human.

Assessing the population density of the spotted paca, Cuniculus paca, (Rodentia: Cuniculidae) on an Atlantic Forest island, southeastern Brazil

The spotted paca,Cuniculuspaca (Linnaeus, 1766), is a Neotropical, opportunistic, frugivorous caviomorph rodent, that inhabits primarily broadleaf forests. We aimed to provide the first estimates of density of C.paca for the Ilha Grande, an island located in the Atlantic Rain Forest biome of Brazil. Density and population size were estimated using the total number of individuals observed along each trail through the program DISTANCE 7. Our estimates of density and population size reinforces the importance of the Ilha Grande as an important reservoir of the species. Therefore, the results presented herein can be a starting point to support future action plans for the species, making predictions regarding the ecosystem and management and conservation of the spotted paca. Furthermore, the results can be used as a surrogate for other regions in which the species occurs.

Geography of current and future global mammal extinction risk

Identifying which species are at greatest risk, what makes them vulnerable, and where they are distributed are central goals for conservation science. While knowledge of which factors influence extinction risk is increasingly available for some taxonomic groups, a deeper understanding of extinction correlates and the geography of risk remains lacking. Here, we develop a predictive random forest model using both geospatial and mammalian species' trait data to uncover the statistical and geographic distributions of extinction correlates. We also explore how this geography of risk may change under a rapidly warming climate. We found distinctive macroecological relationships between species-level risk and extinction correlates, including the intrinsic biological traits of geographic range size, body size and taxonomy, and extrinsic geographic settings such as seasonality, habitat type, land use and human population density. Each extinction correlate exhibited ranges of values that were especially associated with risk, and the importance of different risk factors was not geographically uniform across the globe. We also found that about 10% of mammals not currently recognized as at-risk have biological traits and occur in environments that predispose them towards extinction. Southeast Asia had the most actually and potentially threatened species, underscoring the urgent need for conservation in this region. Additionally, nearly 40% of currently threatened species were predicted to experience rapid climate change at 0.5 km/year or more. Biological and environmental correlates of mammalian extinction risk exhibit distinct statistical and geographic distributions. These results provide insight into species-level patterns and processes underlying geographic variation in extinction risk. They also offer guidance for future conservation research focused on specific geographic regions, or evaluating the degree to which species-level patterns mirror spatial variation in the pressures faced by populations within the ranges of individual species. The added impacts from climate change may increase the susceptibility of at-risk species to extinction and expand the regions where mammals are most vulnerable globally.

Future threats to biodiversity and pathways to their prevention

Tens of thousands of species are threatened with extinction as a result of human activities. Here we explore how the extinction risks of terrestrial mammals and birds might change in the next 50 years. Future population growth and economic development are forecasted to impose unprecedented levels of extinction risk on many more species worldwide, especially the large mammals of tropical Africa, Asia and South America. Yet these threats are not inevitable. Proactive international efforts to increase crop yields, minimize land clearing and habitat fragmentation, and protect natural lands could increase food security in developing nations and preserve much of Earth's remaining biodiversity.

Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals

Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects of habitat fragmentation on the world's terrestrial mammals, including 4,018 species across 26 taxonomic Orders. Results demonstrate that species with more fragmentation are at greater risk of extinction, even after accounting for the effects of key macroecological predictors, such as body size and geographic range size. Species with higher fragmentation had smaller ranges and a lower proportion of high-suitability habitat within their range, and most high-suitability habitat occurred outside of protected areas, further elevating extinction risk. Our models provide a quantitative evaluation of extinction risk assessments for species, allow for identification of emerging threats in species not classified as threatened, and provide maps of global hotspots of fragmentation for the world's terrestrial mammals. Quantification of habitat fragmentation will help guide threat assessment and strategic priorities for global mammal conservation.

Determining causes of genetic isolation in a large carnivore (Ursus americanus) population to direct contemporary conservation measures

The processes leading to genetic isolation influence a population’s local extinction risk, and should thus be identified before conservation actions are implemented. Natural or human-induced circumstances can result in historical or contemporary barriers to gene flow and/or demographic bottlenecks. Distinguishing between these hypotheses can be achieved by comparing genetic diversity and differentiation in isolated vs. continuous neighboring populations. In Ontario, American black bears (Ursus americanus) are continuously distributed, genetically diverse, and exhibit an isolation-by-distance structuring pattern, except on the Bruce Peninsula (BP). To identify the processes that led to the genetic isolation of BP black bears, we modelled various levels of historical and contemporary migration and population size reductions using forward simulations. We compared simulation results with empirical genetic indices from Ontario black bear populations under different levels of geographic isolation, and conducted additional simulations to determine if translocations could help achieve genetic restoration. From a genetic standpoint, conservation concerns for BP black bears are warranted because our results show that: i) a recent demographic bottleneck associated with recently reduced migration best explains the low genetic diversity on the BP; and ii) under sustained isolation, BP black bears could lose between 70% and 80% of their rare alleles within 100 years. Although restoring migration corridors would be the most effective method to enhance long-term genetic diversity and prevent inbreeding, it is unrealistic to expect connectivity to be re-established. Current levels of genetic diversity could be maintained by successfully translocating 10 bears onto the peninsula every 5 years. Such regular translocations may be more practical than landscape restoration, because areas connecting the peninsula to nearby mainland black bear populations have been irreversibly modified by humans, and form strong barriers to movement.

A trait-based approach for predicting species responses to environmental change from sparse data: how well might terrestrial mammals track climate change?

Estimating population spread rates across multiple species is vital for projecting biodiversity responses to climate change. A major challenge is to parameterise spread models for many species. We introduce an approach that addresses this challenge, coupling a trait-based analysis with spatial population modelling to project spread rates for 15 000 virtual mammals with life histories that reflect those seen in the real world. Covariances among life-history traits are estimated from an extensive terrestrial mammal data set using Bayesian inference. We elucidate the relative roles of different life-history traits in driving modelled spread rates, demonstrating that any one alone will be a poor predictor. We also estimate that around 30% of mammal species have potential spread rates slower than the global mean velocity of climate change. This novel trait-space-demographic modelling approach has broad applicability for tackling many key ecological questions for which we have the models but are hindered by data availability.