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Social jetlag (SJ) occurs when sleep-timing irregularities from social or occupational demands conflict with endogenous sleep–wake rhythms. SJ is associated with evening chronotype and poor mental health, but mechanisms supporting this link remain unknown. Impaired ability to retrieve extinction memory is an emotion regulatory deficit observed in some psychiatric illnesses. Thus, SJ-dependent extinction memory deficits may provide a mechanism for poor mental health. To test this, healthy male college students completed 7–9 nights of actigraphy, sleep questionnaires, and a fear conditioning and extinction protocol. As expected, greater SJ, but not total sleep time discrepancy, was associated with poorer extinction memory. Unexpectedly, greater SJ was associated with a tendency toward morning rather than evening chronotype. These findings suggest that deficient extinction memory represents a potential mechanism linking SJ to psychopathology and that SJ is particularly problematic for college students with a greater tendency toward a morning chronotype.
Darwin's frogs Rhinoderma darwinii and Rhinoderma rufum are the only known species of amphibians in which males brood their offspring in their vocal sacs. We propose these frogs as flagship species for the conservation of the Austral temperate forests of Chile and Argentina. This recommendation forms part of the vision of the Binational Conservation Strategy for Darwin's Frogs, which was launched in 2018. The strategy is a conservation initiative led by the IUCN SSC Amphibian Specialist Group, which in 2017 convened 30 governmental, non-profit and private organizations from Chile, Argentina and elsewhere. Darwin's frogs are iconic examples of the global amphibian conservation crisis: R. rufum is categorized as Critically Endangered (Possibly Extinct) on the IUCN Red List, and R. darwinii as Endangered. Here we articulate the conservation planning process that led to the development of the conservation strategy for these species and present its main findings and recommendations. Using an evidence-based approach, the Binational Conservation Strategy for Darwin's Frogs contains a comprehensive status review of Rhinoderma spp., including critical threat analyses, and proposes 39 prioritized conservation actions. Its goal is that by 2028, key information gaps on Rhinoderma spp. will be filled, the main threats to these species will be reduced, and financial, legal and societal support will have been achieved. The strategy is a multi-disciplinary, transnational endeavour aimed at ensuring the long-term viability of these unique frogs and their particular habitat.
A growing body of literature proposes that our ancestors contributed to large mammal extinctions in Africa long before the appearance of Homo sapiens, with some arguing that premodern hominins (e.g., Homo erectus) triggered the demise of Africa's largest herbivores and the loss of carnivoran diversity. Though such arguments have been around for decades, they are now increasingly accepted by those concerned with biodiversity decline in the present-day, despite the near complete absence of critical discussion or debate. To facilitate that process, here we review ancient anthropogenic extinction hypotheses and critically examine the data underpinning them. Broadly speaking, we show that arguments made in favor of ancient anthropogenic extinctions are based on problematic data analysis and interpretation, and are substantially weakened when extinctions are considered in the context of long-term evolutionary, ecological, and environmental changes. Thus, at present, there is no compelling empirical evidence supporting a deep history of hominin impacts on Africa's faunal diversity.
This work proposes and analyzes a family of spatially inhomogeneous epidemic models. This is our first effort to use stochastic partial differential equations (SPDEs) to model epidemic dynamics with spatial variations and environmental noise. After setting up the problem, the existence and uniqueness of solutions of the underlying SPDEs are examined. Then, definitions of permanence and extinction are given, and certain sufficient conditions are provided for permanence and extinction. Our hope is that this paper will open up windows for investigation of epidemic models from a new angle.
This concluding chapter locates our present geological moment politically and economically, arguing that the major ecological degradation which has been made visible at the level of geological time is a result of the Lockean designation of ‘unused’ land as waste to be made productive. And crucially, this designation of land as waste goes hand in hand with the extraction from deep time: it involves bracketing out the long-term history of the landscape and its ecological future for the work of extracting economic value in the now. To expand our time horizons is, in fact, to recognise the contemporary relationship with deep time as wastage.
Beginning with an ethnography of controversy in the representation of time at the Giant’s Causeway, County Antrim, this chapter focuses on the role of catastrophe as rupture in time, confronting us with the transformative potential of events that render planetary history radically discontinuous. Yet while in the nineteenth- and early twentieth-century history of the earth sciences catastrophism became displaced as orthodoxy by uniformitarian explanations, becoming a shadow mode of explanation associated primarily with Christian Biblical literalism, the significance of catastrophe in earth history has re-emerged in a distinct form through the recognition of mass extinction events. Indeed, it has a particular contemporary significance, as we increasingly recognise our own extractive relationship with time as catastrophe: vectors of a mass extinction event, the likes of which have occurred only five times in the last 540 million years or so.
The biosphere is undergoing an epidemic of human-caused extinctions. They greatly exceed background extinction rates, overstepping planetary boundaries for marine and terrestrial biodiversity loss. This destruction of wildlife abundance and reduction in range occupancy has been termed ‘the great thinning’. Multiple lines of evidence (e.g. numbers of threatened species on the IUCN Red List, the Living Planet Index) reveal that endangerment of freshwater biodiversity is greater than on land or in the sea: charismatic species such as the Yangtze River dolphin have become extinct; large fishes, amphibians and pearly mussels (Unionidae) are also at particular risk. Many Red List species classified as ‘Data Deficient’ may well be endangered. High levels of local endemism and species turn-over among freshwater bodies increases global biodiversity, but means they are not substitutable in terms of their species complements. Some fresh waters (e.g. ancient lakes such as Tanganyika) are hyper-diverse with many endemics. In in the case of Asian peatswamps, further degradation would result in species losses, a significant influence on the global carbon balance and on climatic warming.
Frogs have been harvested from the wild for the last 40 years in Turkey. We analysed the population dynamics of Anatolian water frogs (Pelophylax spp.) in the Seyhan and Ceyhan Deltas during 2013–2015. We marked a total of 13,811 individuals during 3 years, estimated population sizes, simulated the dynamics of a harvested population over 50 years, and collated frog harvest and export statistics from the region and for Turkey as a whole. Our capture estimates indicated a population reduction of c. 20% per year, and our population modelling showed that, if overharvesting continues at current rates, the harvested populations will decline rapidly. Simulations with a model of harvested population dynamics resulted in a risk of extinction of > 90% within 50 years, with extinction likely in c. 2032. Our interviews with harvesters revealed their economic dependence on the frog harvest. However, our results also showed that reducing harvest rates would not only ensure the viability of these frog populations but would also provide a source of income that is sustainable in the long term. Our study provides insights into the position of Turkey in the ‘extinction domino’ line, in which harvest pressure shifts among countries as frog populations are depleted and harvest bans are effected. We recommend that harvesting of wild frogs should be banned during the mating season, hunting and exporting of frogs < 30 g should be banned, and harvesters should be trained on species knowledge and awareness of regulations.
Invasive predators have decimated island biodiversity worldwide. Rats (Rattus spp.) are perhaps the greatest conservation threat to island fauna. The ground nesting Palau Micronesian Scrubfowl Megapodius laperouse senex (Megapodiidae) inhabits many of the islands of Palau’s Rock Island Southern Lagoon Conservation Area (RISL) in the western Pacific. These islands are also heavily visited by tourists and support populations of introduced rats, both of which may act as added stressors for the scrubfowl. Using passive chew-tag and call playback surveys on five tourist-visited and five tourist-free islands, we investigated if rats and tourists negatively affect scrubfowl, and if higher rat activity is associated with tourist presence. Rat detection probability and site occupancy were significantly higher on tourist visited (89% and 99%, respectively) compared to tourist-free islands (52% and 73%). Scrubfowl were detected at significantly more stations on tourist-free (93%) than tourist visited (47%) islands and their relative abundance was higher (2.66 and 1.58 birds per station, respectively), although not statistically significantly. While rat occupancy probability likewise had a non-significant negative effect on scrubfowl numbers across islands, our results show a negative relationship between tourist presence and scrubfowl in the RISL. Our findings also suggest that rat populations may be augmented by tourist visitation in the RISL. Although this situation may not seriously affect the scrubfowl, it may be highly detrimental to populations of other threatened island landbirds.
African White-backed Vultures were recently uplisted to ‘Critically Endangered’ by IUCN due to declines across their range. Poisoning is widely accepted as the major reason for these declines. Botswana supports a high number of this species (breeding pairs > c.1,200), but as yet no published information exists on their breeding success in the country. However, mass poisonings within Botswana and neighbouring countries have killed thousands of White-backed Vultures in recent years. We therefore expected that nesting numbers may have declined in this region if these poisoning events killed local breeding birds. We used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two important breeding areas for this species in north-central Botswana, to determine if there was any change in nesting numbers and breeding success of White-backed Vultures. Results showed an overall 53.5% decline in nesting numbers, with a greater decline in Linyanti than in Khwai. In both areas, breeding success was significantly lower in 2017 than it was 10 ten years earlier. We recommend that similar repeat surveys are continued to provide greater confidence in the trends of both nesting numbers and breeding performance. Population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current productivity levels for this population, and if recent high poisoning rates continue, this population could be extirpated from the area in the next 13 years.
We assessed hemisphere function in right-handed male chronic, disorganized type schizophrenic patients (N = 60, age range 18–45 years) using the Quality Extinction Test (QET), in comparison to 20 right-handed male healthy controls in the same age range. The QET analysis discriminated between the disorganized schizophrenic patients and the controls. QET results indicated that chronic schizophrenic patients were less sensitive to tactile stimuli in both hands as compared to controls. Furthermore, the sensitivity to tactile stimuli of the left hand was less than that of the right hand in the schizophrenic patients. In contrast, in the normal controls the sensitivity was similar in both hands. These results indicate possible right hemisphere dysfunction together with disturbance in interhemispheric transmission through the corpus callosum in chronic, disorganized type schizophrenic patients.
La réponse normale ou pathologique à la peur peut être étudiée par un protocole de conditionnement à la peur et à son extinction. Nous avons étudié les mécanismes cérébraux centraux de réponses à la peur à l’aide du modèle pathologique que constitue l’État de Stress Post-Traumatique (ESPT), par un protocole de conditionnement à la peur et à son extinction en IRM fonctionnelle (IRMf). Notre hypothèse est que si ce mécanisme de conditionnement/extinction est central dans l’ESPT, alors après disparition des symptômes, les anomalies fonctionnelles des structures impliquées dans ce mécanisme (amygdale et cortex préfrontal médian) disparaîtront.
Cinquante-deux sujets, 22 témoins sains et 30 patients atteints d’ESPT sont inclus. Les patients effectuaient le protocole de conditionnement à la peur et à son extinction avant puis après traitement et disparition des symptômes. Le contraste d’intérêt était la différence de signal BOLD après moins avant traitement chez les sujets ESPT.
Les patients présentent un retard dans l’extinction d’une peur conditionnée (p < 0,001). Une augmentation du signal BOLD après disparition des symptômes chez les patients ESPT est retrouvée dans des clusters centrés sur le noyau médiodorsal du thalamus, les gyrus frontaux inférieurs et supérieurs gauche (p < 0,005 et k > 5).
Discussion et conclusion
Témoignant d’une dérégulation des réponses à la peur, l’ESPT se caractérise par un déficit dans l’extinction d’une peur conditionnée. Le traitement de l’ESPT restaure la fonction du thalamus et du cortex préfrontal dorsolatéral gauche. Le circuit neuronal sous-jacent aux mécanismes de stress ferait donc intervenir le noyau médiodorsal du thalamus gauche, inhibé chez les malades, qui ne jouerait plus son rôle dans l’encodage et le rappel des informations en lien avec le cortex préfrontal dorsolatéral gauche. Ces structures seraient donc essentielles pour permettre une « extinction » des événements traumatisants, c’est-à-dire une intégration de nos émotions négatives.
Recent research suggests that the brain-derived neurotrophic factor (BDNF) may play a role in extinction learning. The goal of this study was to test whether variation in the BDNF Val66Met polymorphism is related to treatment response to exposure-based cognitive-behavior therapy (CBT), a form of extinction learning, in obsessive-compulsive disorder (OCD).
One hundred and six OCD patients from a specialized clinic, who underwent a standardized CBT treatment after partial or non-response to a 12-week pharmacological trial, were genotyped for the BDNF Val66Met and the relationship between genotype and treatment response was analyzed.
Among 98 CBT completers, 36% of those carrying the BDNF Met allele were rated as CBT responders compared to 60% of nonMet allele carriers (P = 0.027). When analyzing the different obsessive-compulsive symptom dimensions, in patients with contamination/cleaning symptoms, the Met allele was associated with a significantly worse CBT response (P<0.0001) and a lower obsessions severity decrease from pre- to posttreatment (P = 0.046).
Genetic variation in BDNF may be associated with treatment response in exposure-based CBT in OCD, especially in those patients exhibiting contamination/cleaning symptoms.
Conserving species and achieving the Convention on Biological Diversity's international conservation targets necessitates stopping extinctions, recovering depleted populations and maintaining viable populations. The contribution of ex situ management to species conservation has long been debated, and there is limited information on ex situ management activities available in a format that allows success to be assessed. We therefore gathered information from three sources to explore cases in which ex situ management was considered to have had a positive conservation impact for terrestrial vertebrate species. We (1) reviewed the published literature, (2) examined for which taxa ex situ management had contributed to the downlisting of species on the IUCN Red List and (3) surveyed a global network of ex situ management practitioners. We found that ex situ management has contributed to improvements in conservation status for a range of vertebrate species. Ex situ management was reported as contributing to the downlisting of 18 species on the IUCN Red List over a 10-year period. Across sources, the most common role of ex situ management was the provision of individuals to increase population numbers in situ. The strength of evidence for the impact of ex situ management varied within and among sources. Therefore, for the role of ex situ activities in conservation to be understood fully, and for such interventions to reach their potential, documentation of intended and actual benefits needs to be improved. Better reporting of ex situ activities would enable improved learning, facilitating better targeting of ex situ activities to global species conservation goals.
This chapter relaxes the assumption of determistic population growth. It starts with a motivation for the inclusion of stochastic elements in population models and introduces two types of stochasticity: environmental stochasticity and demographic stochasticity. After this, three main probability distributions are introduced: the normal, the binomial and the Poisson. Using these distributions, the dynamics of a small population are simulated and the simulation outcome analysed statistically to assess the viability of the population. A fourth section provides some mathematical background of stochastic population models and population viability analysis. The chapter concludes with an outline of the International Union for Conservation of Nature's risk model to assess the endangerment of species.
A conservation-reliant species is vulnerable to threats that persist; it requires continued management intervention to prevent a decline toward extinction or to maintain a population. The degree of conservation reliance varies over time and among species. Globally, the extent of conservation reliance is accelerating faster than we can provide resources to combat extinctions and promote recovery. A species is recognized as being conservation reliant or emerging from that status based on a general assessment that includes status and threats, the potential for managing the threats, actions taken to manage the threats and the species itself, population monitoring, and monitoring of threats. Species differ in their susceptibility to threats and their potential to respond to management actions, and threats differ in manageability. We use California condor management as a case study for these features of conservation reliance.
In dealing with global changes—including climate, sea levels, and ocean chemistry—traditional approaches to managing species and threats may be unsuccessful. Acting on anticipated changes can improve management effectiveness. Rapid responses may be needed for some threats, such as the effects of extreme weather events. Disruption of ecological relationships among species is a consequence of extinctions and shifting habitats. When functions such as pollination, food provision, or predation are lost, humans may need to take them over a to prevent additional extinctions. Successful planning will account for range shifts and for barriers that include ridges, watercourses, and changing land uses. Species differ in their adaptive capacity in the face of global changes; some may benefit from translocation if suitable receiving habitat is available. Management intervention to build genetic diversity can also be beneficial. Scenario modeling and niche and demographic models can help to anticipate effects of global changes on species of concern. Such modeling can help to prioritize conservation actions designed to prevent imperilment or extinction. Changing regulations that fail to fully acknowledge global changes and associated conservation reliance is essential.
Many species are poorly known, with the sum of our knowledge represented by specimens in museums. For assessment of conservation status the most enigmatic and challenging species are probably those known only from a single specimen. We examine the potential persistence of such species using the orchid flora of Madagascar as a case study. We apply a statistical method that tests the likelihood of species presence in relation to the time when a species was collected and a measure of annual collection effort, calculated in three ways based on specimen collection over time. The results suggest that as of 2000 up to nine of the 236 orchid species known from a single specimen may be inferred to be extinct under at least one of the three methods of estimating collection effort and extinction. In addition, up to two additional species are likely to be extinct by 2018 assuming no new collections were made by that time. Substantial collection effort and/or additional evidence will be needed to reach a decision on the persistence of more recently observed species known only from a single collection. This represents a challenge for conservation practitioners.
We consider an extension of the classical Fisher–Kolmogorov equation, called the “Fisher–Stefan” model, which is a moving boundary problem on
. A key property of the Fisher–Stefan model is the “spreading–vanishing dichotomy”, where solutions with
will eventually spread as
, whereas solutions where
will vanish as
. In one dimension it is well known that the critical length is
. In this work, we re-formulate the Fisher–Stefan model in higher dimensions and calculate
as a function of spatial dimensions in a radially symmetric coordinate system. Our results show how
depends upon the dimension of the problem, and numerical solutions of the governing partial differential equation are consistent with our calculations.
The concluding chapter pulls together key elements of a Green vision for global politics. It summarises the basis o a Green alternative in each of the areas covered in the book: security, economy, the state, global governance, development and sustainability. Recognising diversity of views and multiple theories of change, it suggests critical areas where this vision can be taken forward around the renewal of democracy and subsidiarity, by recommoning and economic democracy, by building new alliances and pursuing just transitions. The politics of the twenty-first century are and will be the politics of sustainability. The question for all of us is: whose politics and on whose terms?