Extinction Risk Of Species Research Articles

Drivers and trends in the extinction risk of New Zealand's endemic birds

New Zealand is well known as the “land of birds” with 168 extant native breeding species within an area of 270,000 km2. About 40 endemic avian species have gone extinct since human arrival 700 years ago, and a high proportion of the remaining ones are currently threatened with extinction. Here, we compile a retrospective assessment of the extinction risk of New Zealand's endemic birds from the 1980s to the present date using global and national information. We projected trends in extinction risk of species during the last four decades as well as trends for species with different life-history characteristics using the Red List Index (RLI). Overall, the RLI of New Zealand endemic birds has decreased from 0.83 in the 1980s to 0.68 in the 2010s, indicating a higher risk of extinction today than 40 years ago. The conservation status of 23 species (64%) deteriorated throughout the study period. We found that flightless and large species are more likely to have a decline in conservation status compared to volant and small species. Ground-nesting birds and those with long incubation times also face higher extinction risk compared to species nesting above 1 m height and short incubation periods. Species classified as habitat specialists and inhabiting water systems showed a more rapid increase in extinction risk than non-specialist species or those inhabiting forests. Our retrospective assessment can help conservationists to identify the characteristics that make endemic birds more likely to face a higher risk of extinction. Integrating historical conservation assessments and species' traits with extinction risk will improve our ability to manage and protect endangered species.

A stochastic structured metapopulation model to assess recovery scenarios of patchily distributed endangered species: Case study for a Mojave Desert rodent.

While metapopulation theory offers tractable means to understand extinction risks for patchily-distributed endangered species, real systems often feature discrepant patch quality and accessibility, complex influences of environmental stochasticity, and regional and temporal autocorrelation. Spatially structured metapopulation models are flexible and can use real data but often at the cost of generality. Particularly as resources for management of such species are often critically limited, endangered species management guided by metapopulation modeling requires incorporation of biological realism. Here we developed a flexible, stochastic spatially structured metapopulation model of the profoundly endangered Amargosa vole, a microtine rodent with an extant population of only a few hundred individuals within 1km2 of habitat in the Mojave Desert. Drought and water insecurity are increasing extinction risks considerably. We modelled subpopulation demographics using a Ricker-like model with migration implemented in an incidence function metapopulation model. A set of scenarios was used to assess the effect of anthropogenic stressors or management actions on expected time to extinction (Te) including: 1) wildland fire, 2) anthropogenically-mediated losses of hydrologic flows, 3) drought, 4) intentional expansion of existing patches into ‘megamarshes’ (i.e. via restoration/enhancement), and 5) additive impacts of multiple influences. In isolation, marshes could be sources or sinks, but spatial context within the full metapopulation including adjacency could alter relative impacts of subpopulations on all other subpopulations. The greatest reductions in persistence occurred in scenarios simulated with impacts from drought in combination with fire or anthropogenically-mediated losses of hydrologic flows. Optimal actions to improve persistence were to prevent distant and smaller marshes from acting as sinks through strategic creation of megamarshes that act as sources of voles and stepping-stones. This research reinforces that management resources expended without guidance from empirically-based modeling can actually harm species’ persistence. This metapopulation-PVA tool could easily be implemented for other patchily-distributed endangered species and allow managers to maximize scarce resources to improve the likelihood of endangered species persistence.

Projecting species loss and turnover under climate change for 111 Chinese tree species

Climate-change-induced habitat loss will be the largest global threat to biodiversity. Therefore, quantifying regional species loss and turnover is important for alerting scientists and policymakers to potential future risks and supporting the development of proactive strategies to reduce the impact of climate change on biodiversity. Here, we projected species turnover and loss for 111 Chinese tree species under four climate change scenarios (representative concentration path ways 2.6 (RCP2.6), RCP4.5, RCP6.0, and RCP8.5). The results show that many Chinese trees will be seriously threatened and the extent of this threat depends firstly on the migration scenarios and secondly on the climate change scenarios. On average across RCP scenarios, about 57% or 23% of the trees would be vulnerable or threatened under no migration assumption or universal migration by 2070, respectively. Projection of species loss and turnover in grid cells indicates considerable variation across climate change scenarios (22–50% and 40–67%, respectively) and across geographical regions (25.4–58.1% and 40.6–78.8%, respectively). Species from arid regions and monsoon regions will undergo more species loss than alpine regions under climate change. This is the opposite for species turnover. Notably, extinction risks for Chinese trees species may be high; even under the most conservative situation (RCP2.6 and universal migration), 18% trees will still be vulnerable or threatened. We suggest that a further studying trees adaptation strategy to climate change is required to ensure the sustainable development of China's forests.

Phylogenetic and spatial distribution of evolutionary diversification, isolation, and threat in turtles and crocodilians (non-avian archosauromorphs)

BackgroundThe origin of turtles and crocodiles and their easily recognized body forms dates to the Triassic and Jurassic. Despite their long-term success, extant species diversity is low, and endangerment is extremely high compared to other terrestrial vertebrate groups, with ~ 65% of ~ 25 crocodilian and ~ 360 turtle species now threatened by exploitation and habitat loss. Here, we combine available molecular and morphological evidence with statistical and machine learning algorithms to present a phylogenetically informed, comprehensive assessment of diversification, threat status, and evolutionary distinctiveness of all extant species.ResultsIn contrast to other terrestrial vertebrates and their own diversity in the fossil record, the recent extant lineages of turtles and crocodilians have not experienced any global mass extinctions or lineage-wide shifts in diversification rate or body-size evolution over time. We predict threat statuses for 114 as-yet unassessed or data-deficient species and identify a concentration of threatened turtles and crocodilians in South and Southeast Asia, western Africa, and the eastern Amazon. We find that unlike other terrestrial vertebrate groups, extinction risk increases with evolutionary distinctiveness: a disproportionate amount of phylogenetic diversity is concentrated in evolutionarily isolated, at-risk taxa, particularly those with small geographic ranges. Our findings highlight the important role of geographic determinants of extinction risk, particularly those resulting from anthropogenic habitat-disturbance, which affect species across body sizes and ecologies.ConclusionsExtant turtles and crocodilians maintain unique, conserved morphologies which make them globally recognizable. Many species are threatened due to exploitation and global change. We use taxonomically complete, dated molecular phylogenies and various approaches to produce a comprehensive assessment of threat status and evolutionary distinctiveness of both groups. Neither group exhibits significant overall shifts in diversification rate or body-size evolution, or any signature of global mass extinctions in recent, extant lineages. However, the most evolutionarily distinct species tend to be the most threatened, and species richness and extinction risk are centered in areas of high anthropogenic disturbance, particularly South and Southeast Asia. Range size is the strongest predictor of threat, and a disproportionate amount of evolutionary diversity is at risk of imminent extinction.

Scientists' warning on invasive alien species.

ABSTRACTBiological invasions are a global consequence of an increasingly connected world and the rise in human population size. The numbers of invasive alien species – the subset of alien species that spread widely in areas where they are not native, affecting the environment or human livelihoods – are increasing. Synergies with other global changes are exacerbating current invasions and facilitating new ones, thereby escalating the extent and impacts of invaders. Invasions have complex and often immense long‐term direct and indirect impacts. In many cases, such impacts become apparent or problematic only when invaders are well established and have large ranges. Invasive alien species break down biogeographic realms, affect native species richness and abundance, increase the risk of native species extinction, affect the genetic composition of native populations, change native animal behaviour, alter phylogenetic diversity across communities, and modify trophic networks. Many invasive alien species also change ecosystem functioning and the delivery of ecosystem services by altering nutrient and contaminant cycling, hydrology, habitat structure, and disturbance regimes. These biodiversity and ecosystem impacts are accelerating and will increase further in the future. Scientific evidence has identified policy strategies to reduce future invasions, but these strategies are often insufficiently implemented. For some nations, notably Australia and New Zealand, biosecurity has become a national priority. There have been long‐term successes, such as eradication of rats and cats on increasingly large islands and biological control of weeds across continental areas. However, in many countries, invasions receive little attention. Improved international cooperation is crucial to reduce the impacts of invasive alien species on biodiversity, ecosystem services, and human livelihoods. Countries can strengthen their biosecurity regulations to implement and enforce more effective management strategies that should also address other global changes that interact with invasions.

European bison conservation cannot afford to ignore alternative hypotheses: a commentary on Perzanowski et al. (2019)

European bison conservation cannot afford to ignore alternative hypotheses: a commentary on Perzanowski <i>et al</i>. (2019)

Trees of Panama: A complete checklist with every geographic range

BackgroundCentral America is one of the most diverse floristic provinces in the world, but comprehensive plant lists for the region are incomplete and need frequent updating. Full geographic ranges of individual species are seldom known. Our detailed forest inventory plots of Panama thus lack a global geographic perspective. In order to provide one, we assembled a thoroughly vetted checklist of all tree species of Panama, along with an estimate of each one’s range size based on published specimen records.Results1) Panama has 3043 tree species in 141 families and 752 genera; 57.6% were ≥ 10 m tall and 16.9% were 3-5 m tall.2) The widest ranges were >1.5×107 km2, covering the entire neotropics and reaching >30∘ latitude; 12.4% of the species had ranges exceeding 107 km2. The median range was 6.9×105 km2.3) At the other extreme, 16.2% of the species had a range <20,000 km2, a criterion suggesting endangered status.4) Range size increased with a tree species’ height and varied significantly among families.5) Tree census plots, where we mapped and measured all individuals, captured 27.5% of the tree species, but a biased selection relative to range size; only 4.5% of the species in plots had ranges <20,000 km2.ConclusionsOur checklist of the trees of Panama, based on rigorous criteria aimed at matching plot censuses, is 20% larger than previous. By recording species’ maximum heights, we allow comparisons with other regions based on matching definitions, and the range sizes provide a quantitative basis for assessing extinction risk. Our next goal is to merge population density from plot censuses to add rigor to predictions of extinction risk of poorly-studied tropical tree species.

Status and priority conservation actions for Australian frog species

Coherent, multi-species conservation strategies rely on up-to-date assessments of extinction risk, and prioritising and implementing well-founded management and research actions. Using IUCN criteria and methods, we reassessed the conservation status of all 243 Australian frog species. We also identified key threats and associated potential management actions. We subsequently scored the relative value, feasibility and current levels of implementation of all management and research actions for threatened and Data Deficient species. These scores were then used to rank the relative priority of management and research actions, identifying the highest priority actions for reducing extinction risk for Australia's frogs. Our revised assessment identified 45 threatened frog species in Australia, a 10% reduction from the 2004 assessment. However, the number of species assessed as Extinct increased by two, and four species were added to the Critically Endangered list. Improvements in conservation status for some species resulted from better knowledge and natural population stabilisation or recovery following disease impacts, rather than as a consequence of management. Improved knowledge has also resulted in a reduction of Data Deficient species from ten to eight. We found substantial reductions in species extinction risk may be achievable by implementing a relatively discrete set of well-targeted management and research actions. Given its simple and dynamic nature, our method can be regularly updated with new information, and can also be applied at different geographic scales. Our prioritisation will enable improved allocation of limited resources to maximise conservation outcomes for Australian frogs.

Generation lengths of the world's birds and their implications for extinction risk.

Birds have been comprehensively assessed on the International Union for Conservation of Nature (IUCN) Red List more times than any other taxonomic group. However, to date, generation lengths have not been systematically estimated to scale population trends when undertaking assessments, as required by the criteria of the IUCN Red List. We compiled information from major databases of published life-history and trait data for all birds and imputed missing life-history data as a function of species traits with generalized linear mixed models. Generation lengths were derived for all species, based on our modeled values of age at first breeding, maximum longevity, and annual adult survival. The resulting generation lengths varied from 1.42 to 27.87 years (median 2.99). Most species (61%) had generation lengths <3.33 years, meaning that the period of 3 generations-over which population declines are assessed under criterion A-was <10 years, which is the value used for IUCN Red List assessments of species with short generation times. For these species, our trait-informed estimates of generation length suggested that 10 years is a robust precautionary value for threat assessment. In other cases, however, for whole families, genera, or individual species, generation length had a substantial impact on their estimated extinction risk, resulting in higher extinction risk in long-lived species than in short-lived species. Although our approach effectively addressed data gaps, generation lengths for some species may have been underestimated due to a paucity of life-history data. Overall, our results will strengthen future extinction-risk assessments and augment key databases of avian life-history and trait data.

Topography and human pressure in mountain ranges alter expected species responses to climate change

Climate change is leading to widespread elevational shifts thought to increase species extinction risk in mountains. We integrate digital elevation models with a metric of human pressure to examine changes in the amount of intact land area available for species undergoing elevational range shifts in all major mountain ranges globally (n = 1010). Nearly 60% of mountainous area is under intense human pressure, predominantly at low elevations and mountain bases. Consequently, upslope range shifts generally resulted in modeled species at lower elevations expanding into areas of lower human pressure and, due to complex topography, encountering more intact land area relative to their starting position. Such gains were often attenuated at high elevations as land-use constraints diminished and topographic constraints increased. Integrating patterns of topography and human pressure is essential for accurate species vulnerability assessments under climate change, as priorities for protecting, connecting, and restoring mountain landscapes may otherwise be misguided.

Phylogenetic clustering and rarity imply risk of local species extinction in prospective deep-sea mining areas of the Clarion-Clipperton Fracture Zone.

An understanding of the forces controlling community structure in the deep sea is essential at a time when its pristineness is threatened by polymetallic nodule mining. Because abiotically defined communities are more sensitive to environmental change, we applied occurrence- and phylogeny-based metrics to determine the importance of biotic versus abiotic structuring processes in nematodes, the most abundant invertebrate taxon of the Clarion–Clipperton Fracture Zone (CCFZ), an area targeted for mining. We investigated the prevalence of rarity and the explanatory power of environmental parameters with respect to phylogenetic diversity (PD). We found evidence for aggregation and phylogenetic clustering in nematode amplicon sequence variants (ASVs) and the dominant genus Acantholaimus, indicating the influence of environmental filtering, sympatric speciation, affinity for overlapping habitats and facilitation for community structure. PD was associated with abiotic variables such as total organic carbon, chloroplastic pigments equivalents and/or mud content, explaining up to 57% of the observed variability and providing further support of the prominence of environmental structuring forces. Rarity was high throughout, ranging from 64 to 75% unique ASVs. Communities defined by environmental filtering with a prevalence of rarity in the CCFZ suggest taxa of these nodule-bearing abyssal plains will be especially vulnerable to the risk of extinction brought about by the efforts to extract them.

30% land conservation and climate action reduces tropical extinction risk by more than 50%

Limiting climate change to less than 2°C is the focus of international policy under the climate convention (UNFCCC), and is essential to preventing extinctions, a focus of the Convention on Biological Diversity (CBD). The post‐2020 biodiversity framework drafted by the CBD proposes conserving 30% of both land and oceans by 2030. However, the combined impact on extinction risk of species from limiting climate change and increasing the extent of protected and conserved areas has not been assessed. Here we create conservation spatial plans to minimize extinction risk in the tropics using data on 289 219 species and modeling two future greenhouse gas concentration pathways (RCP2.6 and 8.5) while varying the extent of terrestrial protected land and conserved areas from &lt;17% to 50%. We find that limiting climate change to 2°C and conserving 30% of terrestrial area could more than halve aggregate extinction risk compared with uncontrolled climate change and no increase in conserved area.

Natural and human-induced environmental changes and their effects on adaptive potential of wild animal populations.

A major challenge of evolutionary ecology over the next decades is to understand and predict the consequences of the current rapid and important environmental changes on wild populations. Extinction risk of species is linked to populations’ evolutionary potential and to their ability to express adaptive phenotypic plasticity. There is thus a vital need to quantify how selective pressures, quantitative genetics parameters, and phenotypic plasticity, for multiple traits in wild animal populations, may vary with changes in the environment. Here I review our previous research that integrated ecological and evolutionary theories with molecular ecology, quantitative genetics, and long‐term monitoring of individually marked wild animals. Our results showed that assessing evolutionary and plastic changes over time and space, using multi‐trait approaches, under a realistic range of environmental conditions are crucial steps toward improving our understanding of the evolution and adaptation of natural populations. Our current and future work focusses on assessing the limits of adaptive potential by determining the factors constraining the evolvability of plasticity, those generating covariation among genetic variance and selection, as well as indirect genetic effects, which can affect population's capacity to adjust to environmental changes. In doing so, we aim to provide an improved assessment of the spatial and temporal scale of evolutionary processes in wild animal populations.

Stochasticity in social structure and mating system drive extinction risk

AbstractAs anthropogenic activities continue to threaten species across the globe, many populations have seen dramatic reductions in abundance from historical values. While the underlying causes are varied, such long‐term population declines greatly increase these species’ susceptibility to extinction via stochastic processes. Previous research has established that demographic stochasticity and environmental stochasticity play important roles in extinction risk, but few studies have investigated the role of stochasticity in social dynamics, such as group formation and mating systems. Here, we developed a suite of simulation models incorporating different combinations of stochastic processes, while also varying group size and mating system. Using these models, we evaluated the interacting effects of different mating systems coupled with varied sources of stochasticity on extinction risk. Extinction risk was generally higher for populations with mating systems more dependent on even sex ratios in groups (e.g., monogamy). However, in more flexible mating systems (e.g., polygynandry), stochasticity in the formation of individual groups actually reduced extinction risk in certain scenarios. By identifying the factors most important to the stochastic extinction risk of species with different mating systems and social structures, we provide insight into conservation and management strategies for such species facing population declines.

Analysis of the Current Agricultural Production System, Environmental, and Health Indicators: Necessary the Rediscovering of the Pre-hispanic Mesoamerican Diet?

The pre-Columbian Mesoamerican diet was characterized by being diverse, nutritionally balanced, and for integrating a remarkable diversity of plants and hundreds of animal species, mainly insects, fish, amphibians, and reptiles. In recent years, countries that used to have traditional healthy diets (e.g. Mexico, China, and India), now present some of the highest rates of diabetes, obesity, and overweight. The rise of non-communicable diseases (NCD) has been linked to the global consumption of highly processed foods, refined sugars, fats, and flours, typical to the Western diet. Additionally, the environmental footprint of the latter is high, as it requires large agricultural areas, great quantities of pesticides, and produces large amounts of greenhouse gases. Here, we show that by diversifying our current eating habits through the consumption of products that once were part of traditional diets, we could lower the prevalence of NCD, reduce greenhouse gas emissions, promote crop diversification, reduce extinction risk of species due to human activities, and at the same time, reincorporate traditions into socioeconomic processes. To this end, we reviewed World Health Organization (WHO), Food and Agriculture Organization (FAO), and World Bank databases and assessed information on health, agricultural, and environmental variables for the countries with the highest incidence of NCD, over the last 40 years. Furthermore, we focused on Mexico because it is home to the pre-Hispanic Mesoamerican world, but currently displays the highest mortality rates due to diabetes, obesity, and overweight. This country also presents an important rate of land-use change, among other negative environmental issues resulting from the adoption of the Western diet. All these factors place Mexico as an interesting case study. Finally, to mitigate the main health, environmental, and agricultural problems, we suggest that public policies around the world should strive to promote the inclusion of native products from local ancestral diets into daily meals.

Is there an association between the ecological characteristics of anurans from the Brazilian Atlantic Forest and their extinction risk?

Extinctions of anuran amphibians are more alarming compared to all other vertebrates. Several reports of declines come from Atlantic Forest, which currently holds only 1.62% of natural vegetation under full protection. However, despite this degradation, the Atlantic Forest still shelters a great diversity of anurans with a high diversity of specific ecological characteristics. Thus, our objective was to identify which ecological characteristics of anurans from the Atlantic Forest can be associated to this extinction risk, in order to understand how these characteristics can promote the species persistence against environmental disturbance. For each species, we gathered biological/ecological characteristics from literature, as well the extinction risk based on the National List of Endangered Species of Wildlife. In 2015, 547 anuran species had been assigned to the Atlantic Forest, of which 406 had their extinction risk defined. However, we considered only 295 species in our analyses due to the availability of biological/ecological information. We observed that the clutch size and the altitudinal distribution are related to the extinction risk of anurans. Threatened species had a small clutch size and were distributed in low or high areas, whereas non-threatened species had a larger clutch size and were distributed in intermediate altitude areas. Studies that investigate ecological characteristics that determine the extinction risk of species can be useful to assist conservation actions, concentrating efforts to species more sensitive to environmental alterations, besides highlighting the importance of natural history and the ecology of organisms in conservation decisions.

Tracking extinction risk trends and patterns in a mega-diverse country: A Red List Index for birds in Colombia.

Monitoring trends in the extinction risk of species is important for tracking conservation effectiveness. The Red List index (RLI) reflects changes in aggregate extinction risk for sets of species over time (a value of zero means that all species are extinct, a value of one means that all species are categorized as Least Concern). We calculated the first national RLI for birds in Colombia for the period 2002-2016, and disaggregated indices by ecosystems, regions, and species groups. Overall, the status of birds in Colombia has moderately deteriorated during 2002-2016, declining by 0.0000714% per year (the global RLI for birds declined by 0.0297% per year). High Andean forest, paramo, and freshwater are the ecosystems in worst condition. The two regions with the greatest avian diversity contrasted: the Andes has the lowest RLI, and the Amazon the highest. Among species groups, gamebirds, parrots, large frugivores, and forest raptors are the most threatened. Habitat loss from expansion of illicit crops and population declines from hunting were the most important threats. Agricultural expansion, invasive alien animal species, illegal logging and illegal mining are significant threats for some species. Tracking species' extinction risk is important in a country with the highest bird species richness in the world, dynamic spatial patterns of habitat loss, and high levels of endemism. Recent developments provide reasons for both hope and despair. In 2016, a peace agreement ended 50 years of armed conflict. New opportunities for biodiversity conservation, local development based on bird-watching tourism, and advancement in scientific knowledge of birds now occur alongside dramatic increases in deforestation. These new conservation opportunities and challenges provide strong motivation to take advantage of the fact that the overall risk of extinction of birds in Colombia is still relatively low and stable. Effective action is urgently needed while there still is the opportunity to prevent extinctions and safeguard species, particularly those in higher risk categories.

A framework for evaluating the impact of the IUCN Red List of threatened species.

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, a species extinction risk assessment tool, has been guiding conservation efforts for over 5 decades. It is widely assumed to have been instrumental in preventing species from moving closer to extinction and driving recoveries. However, the impact of the IUCN Red List in guiding conservation has not been evaluated. We conducted, transcribed, and coded interviews with experts who use the IUCN Red List across a range of sectors to understand how the list is used in conservation. We developed a theory of change to illustrate how and why change is expected to occur along causal pathways contributing to the long‐term goal of the IUCN Red List and an evaluation framework with indicators for measuring the impact of the IUCN Red List in generating scientific knowledge, raising awareness among stakeholders, designating priority conservation sites, allocating funding and resources, influencing development of legislation and policy, and guiding targeted conservation action (key themes). Red‐list assessments were the primary input leading to outputs (scientific knowledge, raised awareness), outcomes (better informed priority setting, access to funding and resource availability, improved legislation and policy), and impact (implemented conservation action leading to positive change) that have resulted in achievement of IUCN Red List goals. To explore feasibility of attributing the difference made by the IUCN Red List across themes, we studied increased scientific knowledge, raised awareness, access to funding and resource allocation, and increased conservation activity. The feasibility exploration showed increased scientific knowledge over time identified through positive trends in publications referring to the IUCN Red List in the literature; raised awareness of the list following high IUCN activity identified by peaks in online search activity; an increased proportion of conservation funding bodies requesting IUCN Red List status in the application process; and, based on interviews with Amphibian Specialist Group members, red‐list assessments were essential in connecting relevant stakeholders and ensuring conservation action. Although we identified the IUCN Red List as a vital tool in global conservation efforts, it was challenging to measure specific impacts because of its ubiquitous nature. We are the first to identify the influence of the IUCN Red List on conservation.

Incongruence between life-history traits and conservation status in reef corals

Comparative lists of species’ extinction risk are increasingly being used to prioritise conservation resources. Extinction risk is most rigorously assessed using quantitative data on species’ population trajectories, but in the absence of such data, assessments often rely on qualitative estimates based on expert opinion of species abundances, distributions and threats. For example, one-third of coral species are classified as threatened and another third as near threatened on the IUCN Red List, despite a lack of data at the population level for the vast majority of species. Since many taxa show a strong correlation between species traits and extinction risk, an alternate approach is to identify traits associated with extinction in other groups and apply them to the taxon of interest. Here, we examine whether life-history traits associated with stress tolerance, fecundity and habitat specialisation are correlated with Red List conservation status in reef corals. We found no relationship between conservation status and life-history traits, suggesting that either traits identified as important predictors of extinction risk in other taxa are not important in corals, or that conservation status does not accurately reflect species’ relative extinction risk. Therefore, using global-scale extinction risk assessments to inform conservation of coral reefs presents a high risk of ‘silent extinctions’ of undescribed species. We argue that the conservation status for the vast majority of coral species should be ‘data deficient’ and is likely to remain so for the foreseeable future, and that the status and trends of coral populations can only be reliably assessed at relatively small scales.

Extinction debt in local habitats: quantifying the roles of random drift, immigration and emigration.

We developed a time-dependent stochastic neutral model for predicting diverse temporal trajectories of biodiversity change in response to ecological disturbance (i.e. habitat destruction) and dispersal dynamic (i.e. emigration and immigration). The model is general and predicts how transition behaviours of extinction may accumulate according to a different combination of random drift, immigration rate, emigration rate and the degree of habitat destruction. We show that immigration, emigration, the areal size of the destroyed habitat and initial species abundance distribution (SAD) can impact the total biodiversity loss in an intact local area. Among these, the SAD plays the most deterministic role, as it directly determines the initial species richness in the local target area. By contrast, immigration was found to slow down total biodiversity loss and can drive the emergence of species credits (i.e. a gain of species) over time. However, the emigration process would increase the extinction risk of species and accelerate biodiversity loss. Finally but notably, we found that a shift in the emigration rate after a habitat destruction event may be a new mechanism to generate species credits.