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... The debate on using pragmatic targets for species persistence has risen in recent years, the main opposing arguments being based on the need of having readily available targets on the one hand (Traill et al., 2007(Traill et al., , 2010Clements et al., 2011) and on the shortfalls of setting universal targets on the other hand Flather et al., 2011;McCarthy et al., 2011). Yet a fundamental question has been disregarded so far about how to properly scale up persistence targets from population level to species level. ...
... An explicit consideration of the dynamics of spatially structured populations can enhance the definition of local and regional conservation plans (Akçakaya et al., 2007). Methods exist to scale up conservation priorities from local populations to spatially structured populations (McDonald-Madden et al., 2008), we step further from pre- Clements et al., 2011 Presence in at least one ecoregion Spatial conservation prioritization Carnivores Loyola et al., 2009 vious considerations and propose the up-scaling of population persistence target to the species level. The process of scaling up a conservation target, from population to species level, should account for three main steps (Tab. ...
... Defining a target in this context implies the identification of a particular number of individuals that is expected to persist over a certain period of time using one of the available methods. Existing examples include the estimation of MVP values (Brook et al., 2006), the use of empirical fixed population thresholds (Clements et al., 2011) and the calculation of equitable persistence target (Wilson et al., 2010). When the available information is su cient, population-specific targets may be implemented to account for di erential regional requirements. ...
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Setting operational targets for the protection of species is crucial for identifying conservation priorities and for monitoring conservation actions’ effectiveness. The use of quantitative targets for global species conservation has grown in the past ten years as a response to the commitment of reducing extinction rates established by the Convention on Biological Diversity. We reviewed the use of conservation targets in global scale conservation analyses, and found that most of the publications adopted species representation targets, corresponding to an amount of area to be protected. We found no work adequately targeting species’ persistence, i.e. the complement to species extinction risk. Despite the adoption of pragmatic population targets, consisting in a number of individuals to be protected, has been recently proposed for global species conservation, the use of these targets at the species level is not always warranted. Pros and cons of using population persistence targets for species conservation have been discussed, yet the fundamental issue of how to scale these targets from populations to species is still unresolved. We discuss the process of “scaling up” population persistence targets to the species level using habitat distribution models, and test our approach in a case study on the European ground squirrel (Spermophilus citellus). We identified three main steps to be followed: (i) definition of a population target, (ii) characterisation of the species’ populations by means of a habitat suitability model, and (iii) definition of a scaled species target. An up-scaled species target should include multiple conditions reflecting species persistence (number, size, location of the populations to be protected), uniqueness (e.g. evolutionary potential) and representativeness (e.g. presence in different ecosystems). Adopting scaled up species persistence targets within conservation planning approaches can allow protected area plans to give the highest contribution to reducing global species extinction risk.
... Indeed, MVP is a concept implicitly underlying threatened species lists worldwide, including the IUCN Red List (see Paper 10). While various methodological issues, genetic considerations and policy implementation problems remain (Clements et al., 2011; Traill et al., 2010a), Shaffer's original paper (Shaffer, 1981) spawned an entire generation of research into quantitative risk assessment in conservation biology, and set the stage for deriving tangible, mathematically based conservation targets (Bradshaw & Brook, 2010). ...
... 'Extinction debt' is the concept that, as habitats become increasingly fragmented, long-lived species that are reproductively isolated from conspecifics can take generations to perish (e.g., large trees in forest fragments). This gives rise to a higher number of species than would be otherwise expected for the size of the fragment, and the false impression that many species can persist in habitat patches that are too small to sustain MVPs (Clements et al., 2011; Traill et al., 2010a). These 'living dead' or 'zombie' species are therefore committed to extinction regardless of whether habitat loss is arrested or reversed. ...
... A population size of 11,500 adults is sufficient to consider the Saint John population not threatened based on a mathematical measure of threat risk (SAFE Index; Clements et al. 2011;Stokesbury et al. 2014). The SAFE index considers any slow-growing and late maturing species with an adult population greater than 5000 to be above the threshold of 'threatened' based on population genetics. ...
... There is no information that COSEWIC provided which conclusively supported any decline in the two populations. Secondly the sturgeon fisheries in the St. Lawrence and the Saint John fulfill all requirements for sustainability and their respective population sizes are near or above the number of adults determined as 'threatened' by the SAFE Index (Clements et al. 2011;Stokesbury et al. 2014). ...
Technical Report
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Contained in this document are comments on the COSEWIC 2011 Atlantic sturgeon assessment document that will be used for the 2015 SARA status assessment of the St. Lawrence and Maritimes Atlantic sturgeon DUs. I have focused my comments on the summaries since these details provide the information that was used to make the COSEWIC assessment of status. Overall the COSEWIC Report contains a considerable number of important facts THAT ARE INCORRECT. Also, much of the data used is OUT-OF-DATE some by as much as 10 years meaning COSEWIC did not pursue newer information with due diligence. No government fisheries agency in Canada or the United States would make an assessment concerning a commercial or angling fishery with such incorrect and out-of-date information. Finally COSEWIC demonstrates a failure to adhere to its own assessment criteria because of lack of data or poor scientific analysis. Where possible corrected and up-to-date information (2015) concerning the Atlantic sturgeon populations in the St. Lawrence and Maritimes DUs is preented in this document. The SARA Status Assessment Committee should advise the Minister of the Environment responsible for SARA to reject the COSEWIC 2011 Report or request that it be rewritten and the status of Atlantic sturgeon in Quebec and the Maritimes reassessed. SUMMARY OF COMMENTS 1. The generation times in the COSEWIC Report for both assessed DUs are incorrect. They are not 40 years but rather 27-29 years for the St. Lawrence River and 25 years for the Saint John River.
... Current abundance plays a prominent role in classifying endangerment (Mace et al. 2008; Vie et al. 2008) because abundance data are widely available and relevant to population viability (Purvis et al. 2000; Clements et al. 2011). For years conservation biologists have proposed minimum abundance thresholds (minimum viable population [MVP]) below which populations have an unacceptable risk of extirpation (Shaffer 1981). ...
... Although some conservation biologists caution against the use of generic MVP thresholds (e.g., Flather et al. 2011), efforts to generalize MVP thresholds across species continue to garner substantial attention (Traill et al. 2010; Bradshaw et al. 2011; Brook et al. 2011). Conservation triage, in which management actions with low probability of success are bypassed in favor of less quixotic efforts, is a logical management response to populations that have fallen well below MVP thresholds (Traill et al. 2010; Clements et al. 2011). However, conservation triage may lead to irreversible loss of species or populations (Pimm 2000). ...
Article
For decades conservation biologists have proposed general rules of thumb for minimum viable population size (MVP); typically, they range from hundreds to thousands of individuals. These rules have shifted conservation resources away from small and fragmented populations. We examined whether iteroparous, long-lived species might constitute an exception to general MVP guidelines. On the basis of results from a 10-year capture-recapture study in eastern New York (U.S.A.), we developed a comprehensive demographic model for the globally threatened bog turtle (Glyptemys muhlenbergii), which is designated as endangered by the IUCN in 2011. We assessed population viability across a wide range of initial abundances and carrying capacities. Not accounting for inbreeding, our results suggest that bog turtle colonies with as few as 15 breeding females have >90% probability of persisting for >100 years, provided vital rates and environmental variance remain at currently estimated levels. On the basis of our results, we suggest that MVP thresholds may be 1-2 orders of magnitude too high for many long-lived organisms. Consequently, protection of small and fragmented populations may constitute a viable conservation option for such species, especially in a regional or metapopulation context.
... Combining further monitoring of breeding numbers with a population genetic appraisal would be decisive for properly listing the species as Endangered or Critically Endangered. Clements et al. (2011) ...
... This illustrates previous criticisms related to the oversimplification of this index for ranking threatened species (Akçakaya et al., 2011; Beissinger et al., 2011) given that, contrarily to IUCN criteria, it relies only on population sizes thus overlooking several key distribution and demographic parameters. It has been argued that the SAFE index may be a useful tool for triage to allocate resources in conservation in the case a number would be more informative than the IUCN threat categories (Clements et al., 2011; Bradshaw et al., 2011). However, the variety of values we obtained depending on the population and MVP data used, even within a range indicating this and other endangered species could be considered as unthreatened , makes triage decisions highly uncertain. ...
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The IUCN Red List is challenged with assessing the conservation status of species on which reliable demographic and distribution parameters are lacking. The hotly debated SAFE index, however, measures the ''species' ability to forestall extinction'' and only requires information on population size. Nonetheless, both conservation assessment systems neglect the role of non-breeding population fractions in conservation. We conducted simple surveys to ascertain the spatial and population structure and conservation threats of the Endangered red-fronted macaw Ara rubrogenys, endemic to the Bolivian Andes. The area of occupancy (ca. 2600 Km 2) encompassed eight breeding and six non-breeding areas, occupied by 807 individuals. By combining population-fraction censuses with the proportion of juveniles (8.6%), we inferred a breeding population of less than 100 pairs clumped in 38–40 nesting sites, with non-breeders representing ca. 80% of the population. While this increase in data quality raises questions as to whether the species should be upgraded to Critically Endangered, the SAFE index rendered questionable guidance for conservation triage. Conservation threats were spatially identified according to spatio-temporal and life-stage population structures and seasonal changes in habitat use. Several sources of habitat loss were widespread but, contrary to expectation, habitat-use models indicated that red-fronted macaws were not tied to forest remnants. Instead, they made use of agricultural lands resulting in conflicts with farmers. Awareness campaigns should focus on a few selected locations to resolve this conflict and reduce the uptake of individuals for use as pets, as the most effective way to increase population size in the medium term .
... It has been proposed that the IUCN threat categories are ambiguous and do not define a risk status for a species in relation to a minimum viable population (MVP) size (Thomas, 1990; Traill et al., 2010). Recently, Clements et al. (2011) proposed a heuristic measure, the Species Ability to Forestall Extinction or " SAFE " Index, which they demonstrated was a better predictor of IUCN threat categories than percentage range loss. The SAFE Index predicts a species distance from extinction by incorporating population size as a variable. ...
... The SAFE index (Clements et al., 2011) was calculated as: ...
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Sturgeon species worldwide have undergone population declines due to habitat alteration and overexploitation and many are listed by the International Union for Conservation of Nature (IUCN) and national agencies. Atlantic and shortnose sturgeon on the east coast of North America are listed as "endangered" or "threatened" over most of their ranges. It has been proposed, however, that IUCN risk categories are ambiguous and do not consider the threat status of a species in relation to a minimum viable population level. Here, we examine the Species Ability to Forestall Extinction (SAFE) Index, which is a heuristic measure of a species relative distance from extinction, and other available information on Atlantic and shortnose sturgeon with regard to the risk status of the two species. To move beyond a 'tipping point' designation of threatened, the SAFE Index requires a species abundance of 5000 adults (SAFE Index D 0.0). DNA and mark-recapture data for Atlantic sturgeon in Minas Basin, Canada indicates a USA/Canada mixed stock of similar to 10,000 fish aggregate there in summer. The SAFE Index for this population is 0.28 indicating abundance is within the "vulnerable" threshold range for the Index although it includes but a small portion of the Atlantic sturgeon in the western Atlantic. Estimates for the east coast of North America suggest the Atlantic sturgeon population could consist of similar to 177,000 sub adults and adults for a SAFE Index of 1.55. Additionally, the present spawning range of Atlantic sturgeon in North America is similar to 99% of the historically known range and the number of stocks is near the historic level (33+) which means the species does not meet IUCN criteria for listing. Similarly, shortnose sturgeon has an Atlantic coast population of similar to 96,800 adults (SAFE Index of 1.29) and a species range and number of stocks (26+) that has not changed substantially from the historical situation. Since the abundance of Atlantic and shortnose sturgeon are well above the SAFE threshold for "threatened" and they lack other accepted criteria for endangered or threatened designation, we conclude that the risk status of both species should be reconsidered.
... The minimum viable population (MVP) concept was originally conceived as a species-specific abundance threshold below which stochastic threats pose an unacceptable risk to an isolated population (Shaffer 1981) (i.e., the population-level definition of MVP). The concept is, however, frequently used in a much broader sense to refer to the minimum number of individuals necessary to ensure long-term persistence of an entire species (e.g., Reed et al. 2003; Clements et al. 2011) (i.e., the specieslevel definition of MVP). We contend that this ambiguity about the MVP concept, along with a difference in perspective on how minimum-abundance thresholds may be manipulated by adversaries of biodiversity conservation, underpins much of the apparent disconnect between Shoemaker et al. (2013) ( " Reexamining the Minimum Viable Population Concept for Long-Lived Species " ) and Reed and McCoy (2014). ...
... Cette TMPV est complètement intégrative (elle inclut implicitement des considérations démographiques, environnementales, génétiques) et représente le plancher en termes de nombre d'adultes reproducteurs nécessaires pour obtenir une population viable à long terme, c'est-à-dire qui ne s'éteint pas car s'affranchissant des aléas démographiques et génétiques inhérents aux petites populations. Ces estimations, « universelles » puisque s'appliquant à toutes les espèces, s'échelonnent entre 1181 et 7316 individus (Reed et al. 2003, Brooks et al. 2006, Traill et al. 2007, Clements et al. 2011. Elles ont été critiquées car elles sont basées sur des espèces et des contextes très hétérogènes. ...
... Cette TMPV est complètement intégrative (elle inclut implicitement des considérations démographiques, environnementales, génétiques) et représente le plancher en termes de nombre d'adultes reproducteurs nécessaires pour obtenir une population viable à long terme, c'est-à-dire qui ne s'éteint pas car s'affranchissant des aléas démographiques et génétiques inhérents aux petites populations. Ces estimations, « universelles » puisque s'appliquant à toutes les espèces, s'échelonnent entre 1181 et 7316 individus (Reed et al. 2003, Brooks et al. 2006, Traill et al. 2007, Clements et al. 2011. Elles ont été critiquées car elles sont basées sur des espèces et des contextes très hétérogènes. ...
Technical Report
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UNE EXPERTISE COLLECTIVE SUR LES ASPECTS ÉCOLOGIQUES ET BIOLOGIQUES En avril 2016, le Ministère chargé de l'Environnement a demandé à l'ONCFS et au MNHN de lancer une démarche prospective d’évaluation écologique de la situation du loup en France à l’horizon 2025/2030 en se fondant sur une expertise collective scientifique indépendante. Le lancement officiel de cette expertise a eu lieu au MNHN le 7 juillet 2016 en présence de Mme Barbara Pompili. Le Ministère chargé de l'Environnement a demandé à l'ONCFS et au MNHN de coordonner des expertises collectives scientifiques indépendantes sur différents aspects de la présence du loup en France. The French Ministry of Environment has asked to ONCFS and MNHN to coordinate independent scientific expertise on different aspects of the wolf's presence in France.
... Nevertheless assessments also contain uncertainties. For example, information is biased towards some taxa and threat status assignments may be subjective (Possingham et al., 2002;Mace et al., 2008;Clements et al., 2011). Further, it is not clear how to assign extinction probabilities to threat status (Collen et al., 2011), and several important questions still need to be addressed: does a change in threat status reflect a continuous or nonlinear change in extinction probability? ...
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The Earth's evolutionary history is threatened by species loss in the current sixth mass extinction event in Earth's history. Such extinction events not only eliminate species but also their unique evolutionary histories. Here we review the expected loss of Earth's evolutionary history quantified by phylogenetic diversity (PD) and evolutionary distinctiveness (ED) at risk. Due to the general paucity of data, global evolutionary history losses have been predicted for only a few groups, such as mammals, birds, amphibians, plants, corals and fishes. Among these groups, there is now empirical support that extinction threats are clustered on the phylogeny; however this is not always a sufficient condition to cause higher loss of phylogenetic diversity in comparison to a scenario of random extinctions. Extinctions of the most evolutionarily distinct species and the shape of phylogenetic trees are additional factors that can elevate losses of evolutionary history. Consequently, impacts of species extinctions differ among groups and regions, and even if global losses are low within large groups, losses can be high among subgroups or within some regions. Further, we show that PD and ED are poorly protected by current conservation practices. While evolutionary history can be indirectly protected by current conservation schemes, optimizing its preservation requires integrating phylogenetic indices with those that capture rarity and extinction risk. Measures based on PD and ED could bring solutions to conservation issues, however they are still rarely used in practice, probably because the reasons to protect evolutionary history are not clear for practitioners or due to a lack of data. However, important advances have been made in the availability of phylogenetic trees and methods for their construction, as well as assessments of extinction risk. Some challenges remain, and looking forward, research should prioritize the assessment of expected PD and ED loss for more taxonomic groups and test the assumption that preserving ED and PD also protects rare species and ecosystem services. Such research will be useful to inform and guide the conservation of Earth's biodiversity and the services it provides.
... In 2011, leading Australian ecologist Corey Bradshaw and his colleagues challenged the tendency in conservation to invest in iconic and charismatic species who live on the brink of extinction, calling instead for the application of a mathematical Species' Ability to Forestall Extinction (SAFE) index that reflects the species' level of viability and its risk of extinction (Clements et al. 2011). Bradshaw's argument became highly contentious because he was quoted suggesting that it might not be worth trying to save the kakapo (Strigops habroptilus), a critically endangered native New Zealand bird that has been on the brink of extinction for decades (Science Media Centre 2011). ...
... However, the lack of high quality population specific data limits the application of such analyses in conservation biology. In order to provide an approach that can be applied in practice, some authors have proposed that a target of a minimum of 5000 individuals per a given species should be set in order to ensure their persistence Clements et al. 2011;Reed et al. 2003;Traill et al. 2010). ...
Technical Report
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In order to assess the significance of the presumed “umbrella effect” of Natura 2000 areas the European Commission initiated a study, in 2013, to address the following questions: 1) Which are, amongst the species regularly occurring within the European territory of the EU-28 Member States, those that significantly benefit from the site conservation under the EU Birds and Habitats Directive? 2) What is the percentage of all species occurring in the wild in the EU that benefit significantly from Natura 2000? 3) How significant is the contribution of Natura 2000 in relation to the objective of halting and reversing biodiversity loss? The approach used existing data, and covered the terrestrial mammals, birds, reptiles, amphibian, butterfly and plant species. The analysis is mostly based on statistical distribution models and GIS processing of species distribution data in relation to their presence within protected areas of the Natura 2000 network. The main findings for all species groups were: Animal species for which Natura 2000 areas were not specifically designated occur more frequently inside Natura 2000 than outside (in particular breeding birds and butterflies). These species do, therefore, gain benefit from the protected areas network. The species for which Natura 2000 areas were designated generally occur more frequently within the Natura 2000 site boundaries than the non-annex species; this is in particular the case for birds and butterflies, for amphibians and reptiles the difference is negligible. More specific conclusions and findings, as well as discussion of these results and implications for further studies are included in the report.
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Biodiversity indices often combine data from different species when used in monitoring programs. Heuristic properties can suggest preferred indices, but we lack objective ways to discriminate between indices with similar heuristics. Biodiversity indices can be evaluated by determining how well they reflect management objectives that a monitoring program aims to support. For example, the Convention on Biological Diversity requires reporting about extinction rates, so simple indices that reflect extinction risk would be valuable. We developed 3 biodiversity indices that are based on simple models of population viability that relate extinction risk to abundance. We based the first index on the geometric mean abundance of species and the second on a more general power mean. In a third index, we integrated the geometric mean abundance and trend. These indices require the same data as previous indices, but they also relate directly to extinction risk. Field data for butterflies and woodland plants and experimental studies of protozoan communities show that the indices correlate with local extinction rates. Applying the index based on the geometric mean to global data on changes in avian abundance suggested that the average extinction probability of birds has increased approximately 1% from 1970 to 2009. © 2014 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of the Society for Conservation Biology.
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For the past decade, the Conservation Measures Partnership's Open Standards for the Practice of Conservation have helped NGOs improve the design and implementation of projects, and measure results. We show how the Open Standards can be used to make better conservation investments as well. We introduce a risk assessment tool that serves to identify issues that inhibit success if not sufficiently addressed and a scorecard for tracking progress towards goals. We report on 25 of the 28 programs managed by the National Fish and Wildlife Foundation (NFWF) that had metrics in place to assess performance. 76% of these programs were on track or further along than expected, while 24% were behind expectations. We argue that scorecards and internal assessments are useful components of a monitoring and evaluation framework, which allows for the early detection of problems. Programs that are behind should not be confused with failures; indeed, there are benefits for the conservation community to move beyond the labels of success and failure. We discuss real-world trade-offs in conservation science due to limited resources. Finally, we suggest ways to avoid what we call the funder's dilemma-where donors feel they either have to adopt monitoring protocols that are too expensive or rely on potentially biased data. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-SA license.
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The effectiveness of fauna reintroduction programs has been limited by the availability of source animals and the lack of follow up monitoring to assess whether viable populations have been successfully established, particularly in terms of conserving genetic diversity. Here we present genetic assessment of the translocation of golden bandicoots (Isoodon auratus) from a large source population on Barrow Island off the north-west coast of Western Australia to two other island sites and a mainland fenced enclosure. We assessed the genetic diversity of animals translocated to each site and their wild-born progeny, and whether wild-born animals showed evidence of genetic bottlenecks or genetic drift from the source population. Encouragingly, we found no significant loss of genetic diversity in any of the wild-born populations compared to the source population and no significant increase in inbreeding or relatedness amongst wild-born individuals compared to founder populations two years post-translocation. However, we detected an approximately 10-fold reduction in effective population size between founding and wild-born populations. We found no apparent differentiation between wild-born populations and the original source population, or between wild-born animals and their respective founders. Population viability modeling predicts that each of the translocated populations is susceptible to loss of genetic diversity over time. Taken together these results suggest that the golden bandicoot reintroduction program has been initially successful as a result of large founding sizes and high reproductive rates; however, ongoing augmentation will be required to prevent genetic erosion and maintain evolutionary potential in the long-term.
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Aim Scenarios of species extinction have been created to assess how the loss of species affects the loss of evolutionary history (EH). However, estimates of the rate of EH loss at regional scales are scarce. Here we provide the first estimate of projected EH loss of New World anurans encompassing both continental and regional scales. Location New World. Methods We implemented two distinct extinction scenarios to investigate variations in rates of EH loss, contrasted through a suboptimality index. The analytical procedure was carried out on a continental scale, comprising all 3017 New World anuran species, and on a regional scale, for each of the 3858 cells of the grid, according to the species assemblage within each cell. Results About 64% of the EH of the New World anurans would still exist even if half of the New World anurans go extinct, regardless of whether extinction is random or threatened species go extinct first. The extinction of all 951 threatened anuran species in the New World, or the same number of species chosen randomly from the 3017 total, would cause similar loss of EH. However, spatially explicit analyses that account for idiosyncrasies in the phylogenetic structure and threat status of each regional assemblage show that EH loss caused by extinction of threatened species is uneven across the continent. Main conclusions Conservation strategies that aim to mitigate pressures on EH loss must be designed with a focus on regional spatial scales, in order to embody the phylogenetic structure and threat status of species that are particular to each assemblage.
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Conservation planning and biodiversity assessments need quantitative targets to optimize planning options and assess the adequacy of current species protection. However, targets aiming at persistence require population-specific data, which limits their use in favor of fixed and non-specific targets, likely leading to unequal distribution of conservation efforts among species. Here we propose a method to derive equitable population targets, which are quantitative targets of population size that ensure equal probabilities of persistence across a set of species, and can be easily inferred from species-specific traits. We applied population dynamics models across a range of life-history traits representative for mammals, and estimated minimum viable population targets intrinsically related to species body mass. Our approach provides a compromise between pragmatic non-specific targets, and detailed context-specific estimates of population viability for which only limited data is available. It enables a first estimation of species-specific population targets based on a readily available trait, and thus allows setting equitable targets for population persistence in large-scale and multispecies conservation assessments and planning. This article is protected by copyright. All rights reserved.
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Over 1,000 mammal species are red-listed by IUCN, as Critically Endangered, Endangered or Vulnerable. Conservation of many threatened mammal species, even inside protected areas, depends on costly active day-to-day defence against poaching, bushmeat hunting, invasive species and habitat encroachment. Many parks agencies worldwide now rely heavily on tourism for routine operational funding: >50% in some cases. This puts rare mammals at a new risk, from downturns in tourism driven by external socioeconomic factors. Using the survival of individual animals as a metric or currency of successful conservation, we calculate here what proportions of remaining populations of IUCN-redlisted mammal species are currently supported by funds from tourism. This proportion is ≥5% for over half of the species where relevant data exist, ≥15% for one fifth, and up to 66% in a few cases. Many of these species, especially the most endangered, survive only in one single remaining subpopulation. These proportions are not correlated either with global population sizes or recognition as wildlife tourism icons. Most of the more heavily tourism-dependent species, however, are medium sized (>7.5 kg) or larger. Historically, biological concern over the growth of tourism in protected areas has centered on direct disturbance to wildlife. These results show that conservation of threatened mammal species has become reliant on revenue from tourism to a previously unsuspected degree. On the one hand, this provides new opportunities for conservation funding; but on the other, dependence on such an uncertain source of funding is a new, large and growing threat to red-listed species.
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Habitat loss and degradation are the factors threatening the largest number of amphibian species. However, quantitative measures of habitat availability only exist for a small subset of them. We evaluated the relationships between habitat availability, extinction risk and drivers of threat for the world's amphibians. We developed deductive habitat suitability models to estimate the extent of suitable habitat and the proportion of suitable habitat (PSH) inside the geographic range of each species, covering species and areas for which little or no high-resolution distribution data are available.
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To ensure both long-term persistence and evolutionary potential, the required number of individuals in a population often greatly exceeds the targets proposed by conservation management. We critically review minimum population size requirements for species based on empirical and theoretical estimates made over the past few decades. This literature collectively shows that thousands (not hundreds) of individuals are required for a population to have an acceptable probability of riding-out environmental fluctuation and catastrophic events, and ensuring the continuation of evolutionary processes. The evidence is clear, yet conservation policy does not appear to reflect these findings, with pragmatic concerns on feasibility over-riding biological risk assessment. As such, we argue that conservation biology faces a dilemma akin to those working on the physical basis of climate change, where scientific recommendations on carbon emission reductions are compromised by policy makers. There is no obvious resolution other than a more explicit acceptance of the trade-offs implied when population viability requirements are ignored. We recommend that conservation planners include demographic and genetic thresholds in their assessments, and recognise implicit triage where these are not met.
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We present the first meta-analysis of a key measure in conservation biology: minimum viable population (MVP) size. Our analysis is based on studies published since the early 1970s, and covers 141 sources and 212 species (after filtering 529 sources and 2202 species). By implementing a unique standardization procedure to make reported MVPs comparable, we were able to derive a cross-species frequency distribution of MVP with a median of 4169 individuals (95% CI = 3577–5129). This standardized database provides a reference set of MVPs from which conservation practitioners can generalize the range expected for particular species (or surrogate taxa) of concern when demographic information is lacking. We provide a synthesis of MVP-related research over the past 30 years, and test for ‘rules of thumb’ relating MVP to extinction vulnerability using well-known threat correlates such as body mass and range decline. We find little support for any plausible ecological and life history predictors of MVP, even though correlates explain >50% of the variation in IUCN threat status. We conclude that a species’ or population’s MVP is context-specific, and there are no simple short-cuts to its derivation. However, our findings are consistent with biological theory and MVPs derived from abundance time series in that the MVP for most species will exceed a few thousand individuals.
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Three of Malaysia's endangered large mammal species are experiencing contrasting futures. Populations of the Sumatran rhino (Dicerorhinus sumatrensis) have dwindled to critically low numbers in Peninsular Malaysia (current estimates need to be revised) and the state of Sabah (less than 40 individuals estimated). In the latter region, a bold intervention involving the translocation of isolated rhinos is being developed to concentrate them into a protected area to improve reproduction success rates. For the Asian elephant (Elephas maximus), recently established baselines for Peninsular Malaysia (0.09 elephants/km2 estimated from one site) and Sabah (between 0.56 and 2.15 elephants/km2 estimated from four sites) seem to indicate globally significant populations based on dung count surveys. Similar surveys are required to monitor elephant population trends at these sites and to determine baselines elsewhere. The population status of the Malayan tiger (Panthera tigris jacksoni) in Peninsular Malaysia, however, remains uncertain as only a couple of scientifically defensible camera-trapping surveys (1.66 and 2.59 tigers/100 km2 estimated from two sites) have been conducted to date. As conservation resources are limited, it may be prudent to focus tiger monitoring and protection efforts in priority areas identified by the National Tiger Action Plan for Malaysia. Apart from reviewing the conservation status of rhinos, elephants and tigers and threats facing them, we highlight existing and novel conservation initiatives, policies and frameworks that can help secure the long-term future of these iconic species in Malaysia.
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Tropical forests are the most biologically diverse and ecologically complex of terrestrial ecosystems, and are disappearing at alarming rates. It has long been suggested that rapid forest loss and degradation in the tropics, if unabated, could ultimately precipitate a wave of species extinctions, perhaps comparable to mass extinction events in the geological history of the Earth. However, a vigorous debate has erupted following a study by Wright and Muller-Landau that challenges the notion of large-scale tropical extinctions, at least over the next century. Here, I summarize this controversy and describe how the debate is stimulating a serious examination of the causes and biological consequences of future tropical deforestation.
The ecology of extinctions in kelp forest communities
  • Ja Estes
  • Do Duggins
  • Rathun Gb
Estes JA, Duggins DO, and Rathun GB. 1989. The ecology of extinctions in kelp forest communities. Conserv Biol 3: 252-64.