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Numerous recent papers have demonstrated a central role for genetic factors in the extinction process or have documented the importance of gene flow in reversing population declines. This prompted one recent publication to declare that a revolution in conservation genetics has occurred. Contemporaneously with this revolution are a series of papers demonstrating long-term population persistence for several species despite having little or no detectable genetic variation. In a couple of notable cases, populations have been shown to have survived for centuries at small population size and with depleted levels of genetic variation. These contradictory results demand an explanation. In this review, I will show that these results do not necessarily fly in the face of theory as sometimes stated. The reconciliation of these two sets of observations relies on the incorporation of two major concepts. (1) Genetic factors do not act in a vacuum and it is their interaction with the environment, the strength and type of selection imposed, and the life history of the organism that determine the relative importance of genetic factors to extinction risk. (2) The relationship between molecular estimates of genetic variation and evolutionary potential, the relevance of genetic bottlenecks to adaptive genetic variation, and the nature of the stochastic process of extinction must be better integrated into expectations of population viability. Reports of populations persisting for hundreds of generations with very little detectable genetic variation provide us not only with valuable information but also with hope. However, recent studies suggest that we should not be sanguine about the importance of genetic diversity in the conservation of biodiversity. [ABSTRACT FROM AUTHOR]

The relative importance of genetic factors in increasing the risk of extinction has been hotly debated in the past and has tended to be downplayed by ecologists researching the correlates of extinction of island endemics. More recently, Frankham has argued that there is now sufficient evidence to regard the past controversies over the contribution of genetic factors to extinction risk as mostly resolved. For example, evidence indicates that the majority of threatened species including island endemics have a lower genetic diversity than taxonomically related nonthreatened species, implying that genetic factors such as inbreeding can increase the probability of extinction before extinction events occur. Yet, recent ecological research on the correlates of extinction for over 220 species of island birds found compelling evidence that exotic mammalian predators were the sole drivers of extinctions, and neglected to even mention any role of genetic factors. This paper discusses how two research groups working towards identifying and understanding the correlates of extinction for island endemics can reach such distinct conclusions. Part of the reason for the different perspectives is that ecological research has tended to focus on the correlates of historical extinctions of island endemics while conservation geneticists have concentrated on genetic correlates of currently threatened extant species. Identifying whether the population growth rate is positive or negative is crucial to this debate because even the geneticists agree that inbreeding will have little time to impact populations that are declining rapidly due to high predation rates. Inbreeding depression is likely to have a greater impact on extinction probability in species suffering from gradual habitat loss and range contraction, which typify the deterministic causes of population decline in continental species, rather than the intense predation pressure commonly associated with declines and extinctions of oceanic island endemics. [ABSTRACT FROM AUTHOR]

Global trait-based analyses can shed light on the factors predisposing species to high extinction risk, and can help bridge knowledge gaps in speciose and poorly known taxa. In this paper, I conduct the first global comparative study of crayfish extinction risk. I collated data on intrinsic (biology and ecology) and extrinsic (environment and threats) factors for 450 crayfish species assessed on the IUCN Red List. Phylogenetic multiple regression models were used to identify correlates of risk in all species; in centres of diversity (American cambarids and Australian parastacids); and among threat types (agriculture, water management, pollution). I assessed the relative ability of threat maps quantifying specific threats (e.g. river fragmentation, mercury deposition) or a generic threat (human population density) to predict crayfish extinction risk. I also quantified the effects of range size on extinction risk with variation partitioning and multiplicative bivariate regressions. Crayfish with small range size, small body size, habitat dependency on caves, and with ranges in areas of low precipitation, high altitude and high human population density were at higher risk of extinction. Correlates of risk varied between American cambarids and Australian parastacids, suggesting that centres of diversity shape patterns of extinction risk in crayfish. The explanatory power of models ranged between 31 and 65%, with low explanatory power for models based on threat types. Few specific threat measures were significantly related to extinction risk, suggesting that large-scale threat mapping may not be informative for freshwater invertebrates. In the absence of population data for most freshwater invertebrates, trait-based models are powerful and cost-effective tools for understanding and mitigating drivers of extinction risk. [ABSTRACT FROM AUTHOR]

Read the Feature Paper: Mapping the potential extinction debt of butterflies in a modern city: implications for conservation priorities in urban landscapes Commentaries on this Feature Paper: Extinction debt at different spatial scales; Setting conservation priorities when what you see is not what you get [ABSTRACT FROM AUTHOR]

Read the Feature Paper: Mapping the potential extinction debt of butterflies in a modern city: implications for conservation priorities in urban landscapes Other Commentaries on this paper: Extinction debt at different spatial scales Response from the authors: From ecological pessimism to conservation chance: reviving living dead in changing landscapes [ABSTRACT FROM AUTHOR]

Read the Feature Paper: Mapping the potential extinction debt of butterflies in a modern city: implications for conservation priorities in urban landscapes Other Commentaries on this paper: Setting conservation priorities when what you see is not what you get Response from the authors: From ecological pessimism to conservation chance: reviving living dead in changing landscapes [ABSTRACT FROM AUTHOR]

Many taxa, including amphibians, have been shown to have a taxonomically non-random distribution of threatened species. There are three possible non-exclusive reasons for this selectivity: non-random knowledge of species conservation status, clades endemic to different regions experiencing different intensities of threatening process and the effects of clade-specific biological attributes on the susceptibility of species to these processes. This paper tests the sufficiency of the first two explanations using extinction risk evaluations from the 2004 Global Amphibian Assessment. Our results indicate that they cannot alone account for the degree of non-randomness in extinction risk among amphibian families. The overall distribution of threatened amphibians remained taxonomically non-random when species of unknown conservation status were omitted, and significant selectivity was detected not only at a global geographic scale but also in country- and site-specific data sets. Furthermore, the same families tend to be over- or underthreatened within different countries. Together, these results suggest that biological differences among amphibian families play an important role in determining species' susceptibility to anthropogenic threatening processes. [ABSTRACT FROM AUTHOR]

Predicting the threat of extinction aids efficient distribution of conservation resources. This paper utilises a comparative macroecological approach to investigate the threat of extinction in Neotropical birds. Data on ecological variables for 1708 species are analysed using stepwise regression to produce minimum adequate models, first using raw species values and then using independent contrasts (to control for phylogenetic effects). The models differ, suggesting phylogeny has significant effects. The raw species analysis reveals that number of zoogeographical regions occupied, elevational range and utilisation of specialised microhabitats were negatively associated with threat, while minimum elevation and body mass were positively associated, whereas the independent contrasts analysis only identifies zoogeographical regions as important. Confining the analysis to the 582 species restricted to a single zoogeographical region reveals elevational range and number of habitats occupied to be negatively correlated with threat whether the analysis is based on the raw data or on independent contrasts. Analysis of four contrasting zoogeographical regions highlights regional variation in the models. In two Andean regions the threat of extinction declines as the elevation range across which the species occurs increases. In the presence of substantial human populations on high Andean plateaus, a species with a greater elevational range may be more likely to persist at some (relatively) unsettled altitudes. In Central South America, the strongest predictor of threat is minimum elevation of occurrence: species with a lower minimum are less threatened. The minimum elevation result suggests that lowland species experiencing an ecological limit to their minimum elevation (min. elevation >0 m) may be more at risk than those not experiencing such a limit (min. elevation = 0 m). Finally, in southern Amazonia, where there is little altitudinal variation, the only weak predictors of threat are body size, larger species being more threatened, and number of habitats, species occupying more habitats being less threatened. These contrasting results emphasise the importance of undertaking extinction risk analyses at an appropriate geographical scale. Since the models explained only a low percentage of total variance in the data, the effects of human-mediated habitat disturbance across a wide range of habitats may be important. [ABSTRACT FROM AUTHOR]

It is becoming increasingly clear that species of smaller body size tend to be less vulnerable to contemporary extinction threats than larger species, but few studies have examined the mechanisms underlying this pattern. In this paper, data for the Australian terrestrial mammal fauna are used to ask whether higher reproductive output or smaller home ranges can explain the reduced extinction risk of smaller species. Extinct and endangered species do indeed have smaller litters and larger home ranges for their body size than expected under a null model. In multiple regressions, however, only litter size is a significant predictor of extinction risk once body size and phylogeny are controlled for. Larger litters contribute to fast population growth, and are probably part of the reason that smaller species are less extinction-prone. The effect of litter size varies between the mesic coastal regions and the arid interior of Australia, indicating that the environment a species inhabits mediates the effect of biology on extinction risk. These results suggest that predicting extinction risk from biological traits is likely to be a complex task which must consider explicitly interactions between biology and environment. [ABSTRACT FROM AUTHOR]

Wolves use howls to maintain large territories, intra-pack communication and social bonding. Besides their physical presence, howls are also instrumental in creating fear and impacting foraging behaviour among the lower cascade. Anthropocene-led behavioural alteration in vocalization has been observed in a wide range of species, but the effect on wolf howl is unknown. In this context, we have studied the howling behaviour of the Indian wolf through playback surveys (n = 264) across the anthropogenic gradient. We found a disparity in their howl response – based on the distance to villages. In the low disturbed East-Maharashtra (EM), wolves mostly avoided responding to howling surveys (HS) if done within 1200 m of villages [response rate (RR) = 0.03 ± 0.021], but they did respond once it was done far from villages (>1200 m) (RR = 0.226 ± 0.075). In high human-density West-Maharashtra (WM), wolves showed high RR within 1200 m from the villages (RR = 0.148 ± 0.031). But the RR within 500 m from villages was less as howling near villages might lead to easy detection. The collared wolf data showed significantly high RR (0.635 ± 0.067) in their home-range core, but low RR if the core area was close to a village. Therefore, howling too close to a village is disadvantageous, although their tolerance for responding to HS has increased in the human-dominated landscape. The extent of the village may increase further with development, which will leave fewer areas for the wolf to defend territory with a long-range howl. The wolves might behaviourally adapt to a human-modified landscape by reducing their howling intensity. Adaptation to a fragmented habitat may save the wolves from extinction, but the repercussions of the fundamental behavioural alteration might adversely impact wolf behaviour and the ecological cascade. Whereas ecologists are mainly concerned with the extinction of species, this study highlights the vulnerability of fundamental behaviour of a keystone species attributed to human-induced contemporary evolution. [ABSTRACT FROM AUTHOR]

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While biological extinctions are predicted to rise sharply during the Anthropocene, extinction declarations are rare, partly due to inherent uncertainties in knowing when the last individual of a species has died. This has led to the growth of a group of 'lost' species that have not been observed in decades or even centuries, yet are not declared extinct, and as such possess an uncertain conservation status. The existence of such species may prove increasingly problematic as the extinction crisis worsens, given that their presence may create uncertainty with respect to conservation prioritization efforts and to our understanding of extinction rates. We provide the first assessment of the extent of lost taxa, defined as species that have not been reliably observed in >50 years yet are not declared extinct, for terrestrial vertebrates (amphibians, reptiles, birds and mammals). We reviewed information from IUCN Red List accounts within these Classes using a hybrid code‐based search/manual assessment approach, supplemented with consultation of recent literature. In total, we identify a total of 562 lost species (137 amphibians, 257 reptiles, 38 birds and 130 mammals). Of these, 13% (75 species) are listed as 'Possibly Extinct' by the IUCN. Lost species outnumber extinct species for all studied Classes except birds. They were mainly confined to the tropics (92.5%), with distributions being particularly concentrated in 'mega‐diverse' countries, as expected. Indonesia (69 species), Mexico (33 species) and Brazil (29 species) possessed the most lost species overall. Our results highlight the prevalence of lost taxa among terrestrial vertebrates and identify 'hotspots' for these species where future survey efforts should be prioritized. We suggest minor adjustments to IUCN Red List accounts to allow lost species to be better tracked, including more consistent use of the 'Possibly Extinct' marker and wider application of the 'last seen date' field. [ABSTRACT FROM AUTHOR]

Large expanses of tropical rainforest have been converted into agricultural landscapes cultivated by smallholder farmers. This is also the case in north‐eastern Madagascar; a region that retains significant proportions of forest cover despite slash‐and‐burn shifting hill rice cultivation and vanilla agroforestry expansion. The region is also a global hotspot for herpetofauna diversity, but how amphibians and reptiles are affected by land‐use change remains largely unknown. Using a space‐for‐time study design, we compared species diversity and community composition across seven prevalent land uses: unburned (old‐growth forest, forest fragment, and forest‐derived vanilla agroforest) and burned (fallow‐derived vanilla agroforest, woody fallow, and herbaceous fallow) land‐use types, and rice paddy. We conducted six comprehensive, time‐standardized searches across at least 10 replicates per land‐use type and applied genetic barcoding to confirm species identification. We documented an exceptional diversity of herpetofauna (119 species; 91% endemic). Observed plot‐level amphibian species richness was significantly higher in old‐growth forest than in all other land‐use types. Plot‐level reptile species richness was significantly higher in unburned land‐use types compared with burned land‐use types. For both amphibians and reptiles, the less‐disturbed land‐use types showed more uneven communities and the species composition in old‐growth forest differed significantly from all other land‐use types. Amphibians had higher forest dependency (38% of species occurred exclusively in old‐growth forest) than reptiles (26%). Our analyses thus revealed that the two groups respond differently to land‐use change: we found less pronounced losses of reptile species richness especially in unburned agricultural habitats, suggesting that reptiles are less susceptible to land‐use change than amphibians, possibly due to their ability to cope with hotter and drier microclimates. In conclusion, our findings emphasize existing conservation opportunities – especially for reptiles – in extensive agricultural landscapes while highlighting the precarious situation of amphibians in disappearing old‐growth forests. [ABSTRACT FROM AUTHOR]

The importance of accounting for temporal variation in vital rates when modelling population dynamics is well recognized. However, long‐term (usually >5 years) datasets are needed to estimate this variation. Consequently, models for newly monitored populations typically assume no temporal variation or use default values provided in software programmes, both of which can give misleading inferences about population dynamics. The goal of this study is to improve estimation of dynamics in the initial years of conservation programmes by incorporating data‐based estimates of temporal variation from other populations with longer‐term data available. We show how data‐derived priors can be generated using estimates of temporal variation in vital rates from other populations, providing information about expected variation until sufficient population‐specific data are available. We specifically evaluated whether data‐derived priors improved our ability to estimate temporal variation for a reintroduced population monitored for 3 years postrelease. We first predicted population growth and probability of extinction assuming no temporal variation in vital rates, then compared projections to those obtained when temporal variation was estimated with uniform priors or with the data‐derived priors. Both types of priors were constrained to plausible ranges, and we also assessed sensitivity of model outputs to widening those ranges. Median projected population size was similar under all three models, but extinction probability was higher with inclusion of temporal variability, reiterating the importance of incorporating this source of uncertainty. Projections with temporal variation were similar irrespective of whether data‐derived priors or uniform priors were used. However, the data‐derived priors generated more precise estimates of annual variation that were less sensitive to relaxation of prior constraints. The approach we present can facilitate management decisions at the outset of conservation programmes when risk assessments that account for all relevant uncertainties can be crucial for determining optimal management strategies. [ABSTRACT FROM AUTHOR]

Climate change and a long legacy of fire suppression are leading to an increased prevalence of 'mega‐disturbances' such as drought and wildfire in terrestrial ecosystems. Evidence for the immediate effects of these novel disturbances on wildlife is accumulating, but little information exists on longer term impacts to species and ecosystems. We studied the occurrence dynamics of an iconic old‐forest species, the spotted owl (Strix occidentalis), on a long‐term study area in the Sierra Nevada, CA, USA from 1989 to 2020 to evaluate their multi‐scale population response following a 2014 megafire (the 'King' Fire) that affected a portion of our study area. We found that extensive severe fire within spotted owl sites resulted in both immediate site abandonment and prolonged lack of re‐colonization by owls six years post‐fire. Sites that experienced high pyrodiversity – a mosaic of burn severities – were more likely to persist after the fire, but this effect was only apparent at finer spatial scales. A potentially confounding factor, post‐fire salvage logging, did not explain variability in the probability of either owls persisting at sites or sites becoming re‐colonized; effects could be attributed only to severe fire extent and pyrodiversity. Our study demonstrates the prolonged effects of severe fire on the occupancy of this forest‐dependent species, suggesting that forest restoration that reduces megafires could benefit spotted owls. Our work emphasizes that long‐term monitoring can offer surprising learning opportunities and provide unparalleled value for understanding and addressing emerging environmental concerns. [ABSTRACT FROM AUTHOR]

Understanding the current population size of small, spatially aggregating populations of species is essential for their conservation. Reliable estimates of the effective population size (Ne) can be used to provide an early warning for conservation managers of the risks to genetic viability of small populations. Critically endangered, migratory swift parrots Lathamus discolor exist in a single panmictic population in Australia. In their Tasmanian breeding range, they are at severe risk of predation by introduced sugar gliders, exacerbated by deforestation. We used three genetic approaches to estimate Ne using DNA samples genotyped by microsatellite markers and existing life‐history data of swift parrots. Based on all samples, we revealed small contemporary Ne estimates across methods (range: 44–140), supporting the need to urgently address threatening processes. Using the 0.5 Ne/N ratio calculated from demographic data suggests that the minimum potential contemporary population size is below 300 individual swift parrots. This is considerably lower than the published estimates derived from expert elicitation, and accords with modeled estimates of extinction risk in this species. Our study has important implications for other threatened species with unknown population sizes and demonstrates that by utilizing available genetic data, reasonable estimates of Ne can be derived. [ABSTRACT FROM AUTHOR]

Fragmented tropical forests can be highly dynamic, with the spatial configuration of forest patches changing through time. Yet, the lack of longitudinal studies limits our understanding of how patch dynamics affect biodiversity, especially when there is a time lag in species extinctions (extinction debt). We assessed how temporal changes in patch size, shape complexity and isolation affect populations of the Mexican howler monkey (Alouatta palliata mexicana), hypothesizing that we would find an extinction debt in this relatively long‐lived species. We assessed patch occupancy, subpopulation size and immature‐to‐female ratio in 39 forest patches from Los Tuxtlas, Mexico, in both 2001 and 2013. To identify time‐lag responses to habitat disturbance, we related demographic attributes in 2013 to patch metrics in 2001 and 2013 and tested whether primate subpopulations were better predicted by current or historical patch characteristics. We also assessed how changes in patch metrics affected each demographic attribute between 2001 and 2013. Patch size and shape complexity increased over time, whereas isolation decreased. These positive spatial changes were accompanied by a 1.6‐fold increase in mean subpopulation size over the same period. In addition, occupancy and immature‐to‐female ratio were similarly related to patch attributes in both years, suggesting that there is no extinction debt. Our findings are 'good news', suggesting that forest recovery over a relatively short period can promote the recovery of this Critically Endangered taxon. They also highlight the importance of preventing forest loss and promoting forest regeneration in human‐modified tropical landscapes. [ABSTRACT FROM AUTHOR]

Wildlife repatriation is an important tool to decrease extinction risk for imperiled species, but successful repatriations require significant time, resources and planning. Because repatriations can be long and expensive processes, clear release strategies and monitoring programs are essential to efficiently use resources and evaluate success. However, monitoring can be challenging and surrounded by significant uncertainty, particularly for secretive species with extremely low detection probability. Here, we simulated how alternative repatriation strategies influence repatriation success for the eastern indigo snake Drymarchon couperi, a federally‐Threatened species that is currently being repatriated in Alabama and Florida. Critically, we demonstrate how observed population growth can differ from true population growth when detection probabilities are low and mark‐recapture analyses are not an option. Specifically, we built a stochastic stage‐based population model to predict population growth and extinction risk under different release strategies and use information from ongoing repatriations to predict success and guide future releases. Because D. couperi is difficult to monitor, we modeled how detection probability influenced perceptions of abundance and population growth by monitoring programs. Simulated repatriation strategies releasing older, head‐started snakes in greater abundance and frequency created wild populations with decreased extinction risk relative to scenarios releasing fewer and younger snakes less frequently. Ongoing repatriations currently have a 0.23 (Alabama) and 0.61 (Florida) probability of quasi‐extinction, but extinction risk decreased to 0.07 and 0.10 at sites upon achieving the targeted number of releases. Abundances observed under realistic detection thresholds for D. couperi did not always predict true population growth; specifically, we demonstrate that monitoring programs during repatriations of secretive species may indicate that efforts have been unsuccessful when populations are actually growing. Overall, our modeling framework informs release strategies to maximize repatriation success while demonstrating the need to consider how detection processes influence assessment of success during conservation interventions. [ABSTRACT FROM AUTHOR]

Only around a third of the world's remaining forest cover survives in the form of Intact Forest Landscapes (IFL), and that proportion is declining. Loss of intactness could impact on biodiversity in many ways but the relationship between intactness and extinction risk has not been quantified. We created Extent of Suitable Habitat (ESH) maps for all the world's forest‐dependent birds and intersected them with an independently derived IFL layer. We also estimate the proportion of the total global range‐rarity of forest‐dependent birds that is captured by IFL. The majority of forest‐dependent bird species are now confined largely or entirely to be degraded, disturbed, or fragmented (non‐IFL) forests. Furthermore, only 22.5% of global hotspots of range‐rarity for forest‐dependent birds are found within intact forests. We find a very strong positive relationship between the global extinction risk of forest‐dependent birds and the proportion of forest within their ESH that is no longer intact. This effect was independent of overall range size and phylogeny. There was also a tendency for extinction risk to be higher in species that lost more intactness in their forest ESHs between 2000 and 2016. Restoring intactness to forest landscapes will reduce global extinction risk in forest‐dependent birds. [ABSTRACT FROM AUTHOR]

Genetic factors have long been a concern in the extinction and viability of species with the short‐term effects focusing on inbreeding depression. Genetic rescue has been suggested as a means to overcome the detrimental effects of inbreeding depression. However, it has been difficult to document the genetic dynamics over time of genetic rescue, inbreeding depression and other genetic relationships in endangered species. We show here using a detailed pedigree and genomic data that genetic rescue in the gray wolf Canis lupus population on Isle Royale had only a temporary positive effect reducing inbreeding depression and then the genetic changes from the immigration event resulted in a population decline and now imminent extinction of the population. Examining the genetic details of this situation shows how genetic dynamics after the initial positive effects of genetic rescue have passed can return a small population to a path toward extinction. Thus, the successful conservation of critically small populations would likely depend on alleviating the cause of having become critically small, such as habitat restoration, or periodic re‐application of genetic rescue in a manner that does not result in negative genetic dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Mobile species pose major challenges for conservation because of their unpredictable, large scale movements in response to fluctuating resources. If locations with critical resources overlap with threats, large proportions of a mobile population may be exposed to threats. Critically endangered and nomadic swift parrots Lathamus discolor nest wherever food is most abundant in their breeding range, but concern exists that nest predation from an introduced predator may severely affect their population. Although swift parrots nest on predator‐free offshore islands, population viability analysis indicates that is land nesting alone may be insufficient to offset extinction risk from high mainland predation rates assuming that the species is a single panmictic population. We test the assumption that swift parrots act as a single conservation unit. We undertook a population genetic analysis using seven microsatellite loci and samples obtained over 6 years from across the breeding range of swift parrots. We found no evidence of departure from Hardy–Weinberg expectations across the species and both Analysis of Molecular Variance and Bayesian Structure analyses failed to detect any evidence for genetic differentiation across the samples both spatially and temporally. These results, supported by simulations, indicate panmixia and a lack of population genetic structure in swift parrots. Unlike a sedentary or site philopatric species, the majority of the swift parrot population may be at risk of exposure to predation when unpredictable resources draw individuals away from islands. These findings support a key assumption of population viability models that predict an extreme reduction in population size for swift parrots, and address a major gap in knowledge of the species’ ecology. Our study has implications both for the development of effective conservation management strategies and for the longer‐term evolution of avoidance of predator‐infested habitat in swift parrots. [ABSTRACT FROM AUTHOR]

Strong social structuring within a population can confer fitness advantages to group members, but may also affect the ability of a population to recover from local extinctions. Opportunities to evaluate the dynamics of the collapse of a sub-population on a vertebrate population in the wild are rare, requiring a crash during a long-term study of marked individuals. Endangered long-tailed bats Chalinolobus tuberculatus, which are members of the widespread family Vespertilionidae, live in closed social groups as evidenced by non-random associations of individuals and a low degree of mixing among colonies. During a 19-year mark-recapture study of long-tailed bats in the Eglinton Valley, New Zealand, one colony of bats collapsed over a 2-year period in which numbers of introduced predators were high. We investigated individual- and colony-level implications of this local extinction event. Survivors (11 known) were assimilated into the neighbouring colony during and immediately after the collapse, but retained higher association rates with individuals from their former colony. The neighbouring colony gradually extended its roosting range into habitat formerly occupied by the extinct colony. Acceptance of individuals into other colonies demonstrates resilience of highly structured vertebrate populations to local crashes. [ABSTRACT FROM AUTHOR]

The author comments on a paper by L. Palazy et al on how trophy harvesting can cause anthropogenic Allee effect (AAE). He cites the assertion of Palazy et al that global trophy hunting has been exposed to be damaging to many species. Also presented is when trophy harvesting can cause AAE like when hunters stop choosing size or sex when animals get extinct. According to the author, Palazy et al help understand the pricing of trophies among species by providing a major step.

Amphibians around the world are declining from threats that cannot currently be mitigated, making it impossible to safeguard some species in their natural habitats. Amphibians in the mountainous neotropics are one example where severe disease-related declines prompted calls for the establishment of captive assurance colonies to avoid extinctions. We surveyed experts in Panamanian amphibians to determine the probability of avoiding chytridiomycosis-related extinctions using captive breeding programs. We ranked Panamanian amphibian species by perceived susceptibility to chytridiomycosis, then calculated the likelihood of avoiding extinction as the product of three probabilities, which include (1) finding sufficient founder animals, (2) successfully breeding these species in captivity and (3) becoming extinct in the wild. The likelihood of finding enough animals to create a captive founding population was low for many rare species, especially for salamanders and caecilians. It was also low for frogs which were once regularly encountered, but have already disappeared including Atelopus chiriquiensis, Craugastor emcelae, C. obesus, C. punctariolus, C. rhyacobatrachus, Ecnomiohyla rabborum, Isthmohyla calypsa and Oophaga speciosa. Our results indicate that captive breeding could improve the odds of avoiding extinction for species that have severely declined or are likely to decline due to chytridiomycosis including Atelopus certus, A. glyphus, A. limosus, A. varius, A. zeteki, Anotheca spinosa, Gastrotheca cornuta, Agalychnis lemur and Hemiphractus fasciatus. Priority species that experts predicted were highly susceptible to chytridiomycosis that might also benefit from ex situ management include Craugastor tabasarae, C. azueroensis, C. evanesco, Strabomantis bufoniformis and Colostethus panamansis. In spite of high levels of uncertainty, this expert assessment approach allowed us to refine our priorities for captive amphibian programs in Panama and identify priority conservation actions with a clearer understanding of the probability of success. [ABSTRACT FROM AUTHOR]

Box turtles Terrapene carolina are long-lived vertebrates found in many habitats throughout eastern North America. Because they routinely live >30-70 years, individuals and populations likely face periodic catastrophic effects from habitat alteration, such as hurricanes and other violent storms, flooding, and climatic perturbations such as cold or drought. We used a dataset based on a 16-year mark-recapture study of a Florida box turtle population inhabiting an isolated island to model the effects of rare and chronic removal of individuals from the population. 'Removing' individuals based on actual sampling records allowed us to compare the resulting effects on population structure and persistence with the known demographic characteristics of the population. For the increasing population, removal had no effect on population size over a projected 50-year time span. However, only the increasing population could sustain an annual loss of up to 56 individuals (3.8% of our initial model population) per year. Beyond this level of annual removal, the population would eventually go extinct. Both the stable and declining populations were projected to become extinct by year 50, regardless of removal intensity. Irrespective of frequency, a pre-reproductive season loss leads to a smaller population than a post-reproductive season loss. These results have implications for understanding the effect of individual removal on population persistence of declining box turtle populations. [ABSTRACT FROM AUTHOR]

Despite recent efforts to develop the science of reintroduction biology, there is still no general and broadly accepted definition of reintroduction success. We investigate this issue based on the postulates (1) that successful reintroduction programs should produce viable populations and (2) that reliable assessments of ultimate success require that populations have reached their regulation phase. We assessed if the viability of these reintroduced populations could be evaluated using the same criteria as for remnant populations, such as the Internation Union for Conservation of Nature ( IUCN) Red List criteria. Using modeling, we projected the viabilities of theoretical populations with various life history and environmental characteristics and we tested whether population sizes (criterion D of the IUCN) and other potential predictors are relevant proxies of the risk of extinction (criterion E of the IUCN) in the case of remnant populations with an unknown past history and in the case of reintroduced populations that have reached their carrying capacity. We found that, as for remnant populations, population size can be used as a relevant indicator (although subject to considerable uncertainty) of the viability of reintroduced populations. However, the results demonstrate the importance of the reintroduction failure filter, that is, the fact that the reintroduced populations that have successfully reached their carrying capacity are those with the highest and more stable growth rates, especially if populations have been reintroduced with a few individuals. As a consequence, the general relationship between the current size of a population and its projected viability will, most likely, differ considerably between remnant and reintroduced populations. Overall, our results demonstrate that there are no theoretical limitations on the application of some of the criteria widely used for remnant populations to define reintroduction success, although these criteria are very conservative for reintroduced populations and might be rescaled to account for the demographic filter that early extinction constitutes for these populations. [ABSTRACT FROM AUTHOR]

Climate change is causing spatio-temporal shifts in environmental conditions, and species that are not able to track suitable environments may face increased risks of extinction. Assisted colonization, a form of translocation, has been proposed as a tool to help species survive the impacts of climate change. Unfortunately, translocations generally have a low success rate, a well-documented fact that is not considered in most of the recent literature on assisted colonization. One of the main impediments to translocation success is inadequate planning. In this review, we argue that by using well-known analytical tools such as species distribution models and population dynamics modelling we can maximize the success of assisted colonization. In particular, we present guidelines as to which questions should be investigated when planning assisted colonization and suggest methods for answering them. Finally, we also highlight further implementation and research issues that remain to be solved for assisted colonizations to be efficient climate change adaptation tools. [ABSTRACT FROM AUTHOR]

Cities are expanding rapidly worldwide. Modern cities are expected to carry heavy extinction debts owing to their recent and drastic fragmentation histories. Therefore, detecting extinction debt and identifying species threatened by it in recently created cities are necessary to prevent future biodiversity losses. Here, we studied the relationship between the life-history traits of butterfly species and the extent of their extinction debts using two different methodological approaches in Tokyo, central Japan. First, we compared the effects of current and past landscape parameters on current species richness using generalized linear models. Second, we predicted species richness in unstable (i.e. high loss) habitats using a model developed for stable (i.e. low loss) habitats. The difference between predicted and observed species richness was used to estimate the extinction debt (the number of species expected to go extinct). We classified butterfly species as seasonal specialists or generalists and as habitat specialists or generalists based on their life-history traits. With both methods, we found significant extinction debts only for specialist species. Mapping the potential extinction debts within our study area indicated that currently large patches had relatively low extinction debts, whereas small patches often had high extinction debts. These results suggested that improving patch area, connectivity and especially quality, would have more significant impacts in small patches than in large ones. Extinction debt is an important concept for setting conservation priorities in highly fragmented landscapes, especially in urban areas. [ABSTRACT FROM AUTHOR]

Ex situ conservation is an important tool for the prevention of species extinction in amphibians. Currently, there is limited information on the nutritional requirements of amphibians in captivity, and there have been anecdotal reports of skin colour degradation in captive amphibians. Amphibians use carotenoids for skin pigmentation, and because carotenoids are only obtainable through the diet, colour degradation could result from limited carotenoid availability. Studies of other vertebrate taxa have shown that carotenoids contribute to health and reproductive success; however, their importance to amphibians is currently unknown. We assessed the influence of carotenoids on the health and development of red-eye tree frogs ( Agalychnis callidryas) during larval and post-metamorphic stages, and looked at effects on skin colour and reproductive success. Carry-over effects of larval exposure to carotenoids were also investigated, and the effects of carotenoids on skin colour development and degradation in adulthood were examined. Carotenoids did not significantly influence larval growth or survival; however, post-metamorphic carotenoid availability significantly increased growth rate in female but not in male frogs. Frogs fed a carotenoid diet post-metamorphosis had significantly redder skin than controls, and larval carotenoid exposure significantly influenced post-metamorphic skin colour. Fecundity was significantly higher in female frogs raised on a carotenoid diet post-metamorphosis compared with controls. Finally, skin colour did not change in adulthood despite changes in dietary carotenoid availability, which suggests that there is a critical period during post-metamorphic growth for deposition of carotenoids in the skin. We have shown that carotenoids influence the development, phenotype and reproductive success of A. callidryas, and these important nutrients should therefore be considered when nutritional recommendations for amphibians are made. [ABSTRACT FROM AUTHOR]

There may be conditions under which trophy hunting can contribute to the conservation of wildlife, but there are cases where its sustainability has been questioned. Several studies have shown that humans place value on rarity, and this may fuel the exploitation of rare species and increase their risk of extinction - a process termed the anthropogenic Allee effect. Previous studies have shown that some rarer species may command higher trophy prices than do broadly similar but less rare ones. Increase in rarity (as measured by International Union for the Conservation of Nature (IUCN) status)) has also been linked to increases in demand as reflected in the volume of recorded trophy hunts. We hypothesized that change in rarity, as measured by change in IUCN status between 2004 and 2010, would have an effect on price if increased demand resulted from the change. Change in rarity was an important predictor of changes in price between 2004 and 2010. Bovids that became more threatened had larger increases in trophy prices than those that did not. Whether this has positive or negative implications for conservation may depend on how well managed the trophy quota setting systems are. [ABSTRACT FROM AUTHOR]

In parts of the Indo-Pacific, large-scale exploitation of the green turtle Chelonia mydas continues to pose a serious threat to the persistence of this species; yet very few studies have assessed the pattern and extent of the impact of such harvests. We used demographic and genetic data in an age-based model to investigate the viability of an exploited green turtle stock from Aru, south-east Indonesia. We found that populations are decreasing under current exploitation pressures. The effects of increasingly severe exploitation activities at foraging and nesting habitat varied depending on the migratory patterns of the stock. Our model predicted a rapid decline of the Aru stock in Indonesia under local exploitation pressure and a shift in the genetic composition of the stock. We used the model to investigate the influence of different types of conservation actions on the persistence of the Aru stock. The results show that local management actions such as nest protection and reducing harvests of adult nesting and foraging turtles can have considerable conservation outcomes and result in the long-term persistence of genetically distinct management units. [ABSTRACT FROM AUTHOR]

Roads can act as barriers to animal movement through mortality during crossing attempts or behavioral avoidance. This barrier effect has negative demographic and genetic consequences that can ultimately result in local or regional extinction. Here we use radio-telemetry data on three terrestrial vertebrates (eastern massasauga Sistrurus catenatus, eastern box turtle Terrapene carolina and ornate box turtle Terrapene ornata) to test whether roads acted as barriers to movement. Specifically, we test whether individuals avoided crossing roads by comparing the number of observed crossings with the number of road crossings predicted by randomizations of individual movement paths. All species crossed roads significantly less often than predicted by chance, indicating strong road avoidance. Results of this study showing behavioral avoidance and previous studies on road mortality indicate that roads are strong barriers to these species. High mortality during crossing attempts would select for road avoidance, reducing the number of individuals killed on roads over time but leading to genetically partitioned subpopulations due to a lack of gene flow. In species that are long-lived and late-maturing, negative genetic effects might not be observable over short time-scales, thus placing populations at high risk of extinction because of a failure to detect an incrementally worsening problem. Formulating successful management strategies for many species in decline will require integrating data on road mortality, animal behavior and population genetics in order to understand more clearly the barrier effect of roads. [ABSTRACT FROM AUTHOR]

One of the most important tasks in conservation biology is identifying species at risk from extinction and establishing the most likely factors influencing this risk. Here, we consider an ecologically well-defined, monophyletic group of organisms, the true hawks of the family Accipitridae, which are not only among the most studied, but also contain some of the rarest bird species in the world. We investigate which intrinsic and extrinsic factors, covering morphology, life history and ecology, covary with International Union for the Conservation of Nature and Natural Resources threat status, as well as global population size and geographic range size. By decomposing threat status into population size and range size, we test whether any factors are generally important: we found that species with less habitat specialization, a larger clutch size and more plumage polymorphism were associated with lower extinction risk and larger population and range sizes. Species with special habitat requirements might be less capable of dealing with habitat transformation and fragmentation, while species with small clutch sizes might not be able to reverse population declines. Plumage polymorphism might indicate the size of the species' gene pool and could be a good marker of extinction risk. The analyses also emphasized that no single factor is likely to be sufficient when predicting the threat of extinction. [ABSTRACT FROM AUTHOR]

The fact that species vary in their vulnerability to extinction is well documented, but the reasons for these differences remain poorly understood. Why should some species/families/guilds decline rapidly with increasing anthropogenic disturbance, while others either tolerate or proliferate in disturbed habitats? We investigated the bird species composition in 31 primary forest patches of varying size in a region of the Amazonian ‘Arc of Deforestation’ and assessed which species life-history traits predisposed individual species to extinction. Medium-sized non-flocking canopy frugivores/ominvores of low primary forest dependence were least likely to go extinct in small patches, while small-bodied flock-following primary-forest-dependent terrestrial insectivores were most fragmentation sensitive. We found highly idiosyncratic relationships between the minimum size of forest patches occupied by different species and their territory size requirements estimated based on other Amazonian studies. This suggests that avian assemblages in forest fragments primarily comprise species that either have good dispersal abilities or are highly tolerant to the non-forest matrix, rather than those whose minimum spatial requirements can be met by the size of available forest fragments. [ABSTRACT FROM AUTHOR]

Matrix models and population viability analysis (PVA) have become useful tools to understand population attributes and dynamics. Demography analysis gives valuable information for the management of threatened species, and can be used to create action plans for their conservation. PVA is particularly useful in those species with small population sizes difficult to sample. By calculating the individual fate of each member of the population, PVA simulates temporal population changes and estimates extinction risk over a time period. Here we use these models to analyse the population of axolotl Ambystoma mexicanum, which has decreased more than six times within only 5 years. Its natural environment (the Xochimilco aquatic system within Mexico City) has deteriorated significantly in the last decades. The matrix analysis showed large oscillations in the axolotl population growth rate (damping behaviour), which could explain the fast density reduction in only few generations. Younger ages (eggs and larvae) showed the highest sensitivity and elasticity values, suggesting that the lack of food sources such as zooplankton or the increased predation by exotic carp and tilapia are capable to reduce axolotl density. PVA shows low extinction probabilities using laboratory data for younger ages. However, a small reduction in egg or larvae survival rate is capable to increase extinction probabilities to 100% in 20 years. Based on these results, we found that the best strategy to restore the axolotl population is to increase the survival rate of eggs and larvae by restoring the habitat, eradicating introduced fish and improving water quality, rather than implementing a reintroduction programme. [ABSTRACT FROM AUTHOR]

Ample evidence exists that an increase in the inbreeding level of a population reduces the value of fitness components such as fecundity and survival. It does not follow, however, that these decreases in the components of fitness impact population dynamics in a way that increases extinction risk, because virtually all species produce far more offspring than can actually survive. We analyzed the effects of the genetic quality (mean fitness) of individuals on the population growth rate of seven natural populations in each of two species of wolf spider in the genus Rabidosa, statistically controlling for environmental factors. We show that populations of different sizes, and different inbreeding levels, differ in population dynamics for both species. Differences in population growth rates are especially pronounced during stressful environmental conditions (low food availability) and the stressful environment affects smaller populations (<500 individuals) disproportionately. Thus, even in an invertebrate with an extremely high potential growth rate and strong density-dependent mortality rates, genetic factors contribute directly to population dynamics and, therefore, to extinction risk. This is only the second study to demonstrate an impact of the genetic quality of individual genotypes on population dynamics in a wild population and the first to document strong inbreeding–environment interactions for fitness among populations. Endangered species typically exist at sizes of a few hundred individuals and human activities degrade habitats making them innately more stressful (e.g. global climate change). Therefore, the interaction between genetic factors and environmental stress has important implications for efforts aimed at conserving the Earth's biodiversity. [ABSTRACT FROM AUTHOR]

In the last 400 years, more species have become extinct on small islands than on continents. Yet, scant attention has hitherto been paid to prioritizing island restorations. Nevertheless, considerable conservation effort is now devoted to removing a major cause of these extinctions – invasive alien vertebrates. Because modern techniques allow the clearance of invasive vertebrates from quite large islands (up to 1000 km2), many islands are candidates for restoration. A robust strategy for allocating available funds is urgently needed. It requires, for each candidate island, an objective estimation of conservation gain and a method for predicting its financial cost. Our earlier work showed that a good first-pass estimate of vertebrate eradication costs can be made using just island area and target species. Costs increase with island area, while rodents are more expensive per unit area than ungulates. Here, we develop a method for assessing the conservation benefit of a proposed eradication and apply the method to threatened birds, but not other taxa. The method, combining information on how threatened a species is, on the impact of alien vertebrates on that species and on the islands on which the species occurs, allows us to present a means of determining which islands yield the greatest conservation benefit per unit of expenditure on vertebrate eradication. In general, although greater overall benefit would accrue to birds from eradication of invasive vertebrates on larger islands, benefit per unit of expenditure is the highest on relatively small islands, and we identify those that should be priority targets for future eradications. Crucially, this quantitative assessment provides considerable efficiency gains over more opportunistic targeting of islands. The method could be adapted to prioritize islands on a regional or national basis, or with different conservation gains in mind. [ABSTRACT FROM AUTHOR]

The Perrier's sifaka Propithecus perrieri, considered critically endangered by the IUCN (World Conservation Union; 2004), is one of the least studied and most endangered primates in the world, yet baseline information on its distribution and population levels has not been updated for over 10 years. Density estimates from former studies suggest that only between 100 and 2000 individuals remain in the wild. In 2003–2004, using the line-transect method, information on the distribution and population levels of this and sympatric primate species were obtained. Multi-spectral, Landsat 7 satellite images of areas comprising the known Perrier's sifaka distribution, acquired in 1994 and 2002, were compared using spatial analysis techniques to quantify regional patterns of deforestation. Results from this study indicate that the global population of the Perrier's sifaka consists of about 915 individuals and the effective population size is unlikely to exceed 230 individuals. Furthermore, an annual deforestation rate of 1.2% was detected in the only protected area where this species occurs. Deforestation, the decline of taboos against hunting and human immigration patterns influence primate population status in northern Madagascar and threaten to drive the Perrier's sifaka to extinction in the near future. [ABSTRACT FROM AUTHOR]

Populations established with a small number of founders are thought to have a high risk of extinction due to allee effects, demographic stochasticity, inbreeding and reduced genetic variation. We tested whether the initial number of birds released was related to persistence in reintroductions of saddlebacks (Philesturnus carunculatus) and robins (Petroica australis) to New Zealand offshore islands. Data were analysed for 31 populations that had been observed for at least 3 years since reintroductions. The numbers released ranged from 5–188. Most of the populations (26) survived and grew, including five from less than 15 founders, and four out of the five extinctions were attributable to introduced mammalian predators. The number of individuals released did not significantly affect extinction probability. The ability of these small releases to establish populations can be attributed to the closed nature of the islands (allowing birds to find mates), low mortality rates following release and high growth rates at low density. Stochastic simulation models based on data from two reintroduced populations suggested that populations with four founders (two male, two female) would have a negligible chance of extinction through demographic stochasticity and would be able to grow even if there were high rates of egg failure through inbreeding. [ABSTRACT FROM AUTHOR]

Population models incorporating demographic, environmental and genetic stochasticity were created from long-term data on natural populations of 30 species of vertebrates. The probability of extinction for a single population in a continuous habitat was compared to that of multiple isolated, or semi-isolated, populations occupying a fragmented landscape with an equivalent total carrying capacity. Populations occupying a fragmented landscape were modelled for a range of dispersal rates and levels of asynchrony in the effects of environmental disturbances. Dispersal among subpopulations in the fragmented landscape partially alleviates the effect of fragmentation on extinction rates, despite the models explicitly incorporating disease epidemics which spread between subpopulations through dispersal. Even moderate environmental correlations among subpopulations greatly reduces the viability of the metapopulation relative to the case where the populations are totally independent. Whether a population performed better as a single population or as a metapopulation was strongly affected by the carrying capacity assumed, the time frame examined and the initial fitness of the population. A single population always fared better when the total habitat available was capable of supporting ≤1000 adults. Thus, continued habitat fragmentation can be expected to fuel the ongoing global extinction crisis and conservation efforts should be aimed at interconnecting isolated habitat patches. [ABSTRACT FROM AUTHOR]

Individual identification was assessed for 30 brown bears (Ursus arctos) from the endangered Apennine population in central Italy, mostly through non-invasive sampling. Shed hairs were used as a source of DNA to obtain single genotype profiling at 12 microsatellite loci. Average expected heterozygosity (0.438) and mean number of alleles per locus (2.2) showed that the level of genetic diversity was one of the lowest recorded for brown bear populations across their European and North American ranges. A large portion of the original genetic variation may have been lost through random genetic drift during the recent period of isolation. The level of genetic variability proved sufficient to identify the bears individually by using nine microsatellite loci. The probability that two animals shared by chance the same multilocus genotype was estimated to be 1 in 100. Despite the recent history of small population size, the average relatedness indicated that the majority of individuals are not first-order relatives. Simulated paternity tests showed that a 12-loci genotype may be necessary to assign paternity with an 80–95% confidence level. Lack of genetic diversity, as well as the maintenance of an adequately effective number, may seriously jeopardise the long-term survival of this population. Furthermore, high mortality rates, poaching and encroachment by human activities represent immediate, urgent concerns. A population increase through enforced protection and habitat restoration is recommended. Presently, restocking with bears from other source populations should be discouraged to avoid genetic extinction. Non-invasive sampling provided reliable population and individual genetic data. Microsatellite genotyping proved a valuable genetic tagging method and a feasible alternative to conventional field counts for the brown bear in central Italy. [ABSTRACT FROM AUTHOR]

The Evolutionarily Distinct and Globally Endangered (EDGE) of Existence programme provides a flagship example about how to address some key challenges in biodiversity conservation. In the Weedop I et al i . study, we can infer that "PD" indeed has the standard meaning of Faith ([2]), noting that ED scores were designed to divide up total PD among species. EDGE of Existence not only uses PD mathematically, but also recognises PD "option value" (see Faith, [5]; Owen I et al. i , [9]). EDGE is now refining its approach (EDGE of Existence, [1]) to use an alternative part of the PD calculus: "expected PD" (reviewed in Faith, [3]; Faith I et al. i , [6]). [Extracted from the article]

The article presents a response to various studies on the role of genetic factors in extinction of species. The author pointed out that genetic factors are accepted to have played a role in the recovery of wild populations. Others have taken the argument that the loss of fitness due to inbreeding depression is seen as an unavoidable consequence of small populations and therefore a contributor to the extinction risk of threatened species. The consequences of island isolation are also cited.

The article comments on several studies about the extinction of endemic population of island bird species. The author said that inbreeding depression played a vital role in the extinction of island endemics. A study suggested that most species are not driven to extinction before genetic factors impact them. The relationship between vertebrate predators and the presence or absence of the bird species is also addressed.