A 'dynamic' landscape of fear: prey responses to spatiotemporal variations in predation risk across the lunar cycle.

Ambiguous empirical support for 'landscapes of fear' in natural systems may stem from failure to consider dynamic temporal changes in predation risk. The lunar cycle dramatically alters night-time visibility, with low luminosity increasing hunting success of African lions. We used camera-trap data from Serengeti National Park to examine nocturnal anti-predator behaviours of four herbivore species. Interactions between predictable fluctuations in night-time luminosity and the underlying risk-resource landscape shaped herbivore distribution, herding propensity and the incidence of 'relaxed' behaviours. Buffalo responded least to temporal risk cues and minimised risk primarily through spatial redistribution. Gazelle and zebra made decisions based on current light levels and lunar phase, and wildebeest responded to lunar phase alone. These three species avoided areas where likelihood of encountering lions was high and changed their behaviours in risky areas to minimise predation threat. These patterns support the hypothesis that fear landscapes vary heterogeneously in both space and time.

The clinical case: validity, values and strategies to approach its writing. / El caso clínico: vigencia, valores y estrategias para abordar su escritura.

The case report is used to communicate the experience acquired by its authors with a patient. Although its relevance has been doubted, the case report deserves to be vindicated and contextualized. We review the case report's historical tradition, recent evolution and current formats. We describe its utility as a scientific tool, a continuing education resource and an aid to diagnosis. We reflect on the teaching potential its writing entails. Finally, we provide strategies to address the writing of a radiological case report.

No lasting legacy: no change in reporting of women's sports in the British print media with the London 2012 Olympics and Paralympics.

BACKGROUND: The proportion of media sports coverage devoted to women is reported at between 1 and 6%. Our survey examines and compares reporting patterns before and after the 2012 Olympics and Paralympics. METHODS: We collected data on sports coverage in six national newspapers on 3 weekend days in February and March 2012, and in February 2013; ∼5 months before the opening of the 2012 Olympic Games and 5 months after the closing of the Paralympic Games. RESULTS: In 2012, 39 of 876 articles in national newspapers (4.5%) related to women's sports, compared with 22 of 755 (2.9%) in 2013; a non-significant reduction in coverage [difference 1.54%, 95% confidence interval (CI) -0.28 to 3.36). In 2012, 24 of 647 pictures (3.7%) related to women's activities, compared with 10 of 738 (1.4%) in 2013; a significant reduction in coverage (difference 2.35%; 95% CI 0.68-4.03). The median area per article was significantly greater for men in both years. CONCLUSIONS: We found a continuing bias towards men's sport in the media analysed and no evidence of improvement either before or after the 2012 Olympics and Paralympics. Increased support of women's sport in the print media could benefit individuals and influence the health of the population.

The case for fencing remains intact.

Creel et al. argue against the conservation effectiveness of fencing based on a population measure that ignores the importance of top predators to ecosystem processes. Their statistical analyses consider, first, only a subset of fenced reserves and, second, an incomplete examination of 'costs per lion.' Our original conclusions remain unaltered.

Conserving large carnivores: dollars and fence.

Conservationists often advocate for landscape approaches to wildlife management while others argue for physical separation between protected species and human communities, but direct empirical comparisons of these alternatives are scarce. We relate African lion population densities and population trends to contrasting management practices across 42 sites in 11 countries. Lion populations in fenced reserves are significantly closer to their estimated carrying capacities than unfenced populations. Whereas fenced reserves can maintain lions at 80% of their potential densities on annual management budgets of $500 km(-2) , unfenced populations require budgets in excess of $2000 km(-2) to attain half their potential densities. Lions in fenced reserves are primarily limited by density dependence, but lions in unfenced reserves are highly sensitive to human population densities in surrounding communities, and unfenced populations are frequently subjected to density-independent factors. Nearly half the unfenced lion populations may decline to near extinction over the next 20-40 years.

Effects of trophy hunting on lion and leopard populations in Tanzania.

Tanzania holds most of the remaining large populations of African lions (Panthera leo) and has extensive areas of leopard habitat (Panthera pardus), and both species are subjected to sizable harvests by sport hunters. As a first step toward establishing sustainable management strategies, we analyzed harvest trends for lions and leopards across Tanzania's 300,000 km(2) of hunting blocks. We summarize lion population trends in protected areas where lion abundance has been directly measured and data on the frequency of lion attacks on humans in high-conflict agricultural areas. We place these findings in context of the rapidly growing human population in rural Tanzania and the concomitant effects of habitat loss, human-wildlife conflict, and cultural practices. Lion harvests declined by 50% across Tanzania between 1996 and 2008, and hunting areas with the highest initial harvests suffered the steepest declines. Although each part of the country is subject to some form of anthropogenic impact from local people, the intensity of trophy hunting was the only significant factor in a statistical analysis of lion harvest trends. Although leopard harvests were more stable, regions outside the Selous Game Reserve with the highest initial leopard harvests again showed the steepest declines. Our quantitative analyses suggest that annual hunting quotas be limited to 0.5 lions and 1.0 leopard/1000 km(2) of hunting area, except hunting blocks in the Selous Game Reserve, where harvests should be limited to 1.0 lion and 3.0 leopards/1000 km(2) .

Sexual dimorphism: the horns of african antelopes.

Comparisons of the horns of males and females across genera of African antelopes indicate that male horns are better adapted for clashing or pushing against another pair of horns during intrasexual combat. The horns of females are relatively more specialized as stabbing weapons. Horns in females are found in only half the genera and in those genera where females have horns, the genera are heavier than genera with hornless females.

Complex cooperative strategies in group-territorial African lions.

Female lions (Panthera leo) showed persistent individual differences in the extent to which they participated in group-territorial conflict. When intergroup encounters were simulated by playback of aggressive vocalizations, some individuals consistently led the approach to the recorded intruder, whereas others lagged behind and avoided the risks of fighting. The lead females recognized that certain companions were laggards but failed to punish them, which suggests that cooperation is not maintained by reciprocity. Modification of the "odds" in these encounters revealed that some females joined the group response when they were most needed, whereas other lagged even farther behind. The complexity of these responses emphasizes the great diversity of individual behavior in this species and the inadequacy of current theory to explain cooperation in large groups.

Egalitarianism in female African lions.

Because most cooperative societies are despotic, it has been difficult to test models of egalitarianism. Female African lions demonstrate a unique form of plural breeding in which companions consistently produce similar numbers of surviving offspring. Consistent with theoretical predictions from models of reproductive skew, female lions are unable to control each other's reproduction because of high costs of fighting and low access to each other's newborn cubs. A female also lacks incentives to reduce her companions' reproduction, because her own survival and reproduction depend on group territoriality and synchronous breeding. Consequently, female relationships are highly symmetrical, and female lions are "free agents" who only contribute to communal care when they have cubs of their own.

Dynamics of a multihost pathogen in a carnivore community.

1. We provide the first theoretical analysis of multihost disease dynamics to incorporate social behaviour and contrasting rates of within- and between-group disease transmission. 2. A stochastic susceptible-infected-recovered (SIR) model of disease transmission involving one to three sympatric species was built to mimic the 1994 Serengeti canine distemper virus outbreak, which infected a variety of carnivores with widely ranging social structures. The model successfully mimicked the erratic and discontinuous spatial pattern of lion deaths observed in the Serengeti lions under a reasonable range of parameter values, but only when one to two other species repeatedly transmitted the virus to the lion population. 3. The outputs from our model suggest several principles that will apply to most directly transmitted multihost pathogens: (i) differences in social structure can significantly influence the size, velocity and spatial pattern of a multihost epidemic; and (ii) social structures that permit higher intraspecific neighbour-to-neighbour transmission are the most likely to transmit disease to other species; whereas (iii) species with low neighbour-to-neighbour intraspecific transmission suffer the greatest costs from interspecific transmission.

Molecular epidemiology identifies only a single rabies virus variant circulating in complex carnivore communities of the Serengeti.

Understanding the transmission dynamics of generalist pathogens that infect multiple host species is essential for their effective control. Only by identifying those host populations that are critical to the permanent maintenance of the pathogen, as opposed to populations in which outbreaks are the result of 'spillover' infections, can control measures be appropriately directed. Rabies virus is capable of infecting a wide range of host species, but in many ecosystems, particular variants circulate among only a limited range of potential host populations. The Serengeti ecosystem (in northwestern Tanzania) supports a complex community of wild carnivores that are threatened by generalist pathogens that also circulate in domestic dog populations surrounding the park boundaries. While the combined assemblage of host species appears capable of permanently maintaining rabies in the ecosystem, little is known about the patterns of circulation within and between these host populations. Here we use molecular phylogenetics to test whether distinct virus-host associations occur in this species-rich carnivore community. Our analysis identifies a single major variant belonging to the group of southern Africa canid-associated viruses (Africa 1b) to be circulating within this ecosystem, and no evidence for species-specific grouping. A statistical parsimony analysis of nucleoprotein and glycoprotein gene sequence data is consistent with both within- and between-species transmission events. While likely differential sampling effort between host species precludes a definitive inference, the results are most consistent with dogs comprising the reservoir of rabies and emphasize the importance of applying control efforts in dog populations.

Quantifying emerging drugs for very rare conditions.

BACKGROUND: EU legislation is encouraging pharmaceutical companies to develop drugs for rare conditions, but their often high cost, and potential for long-term administration has led to debate about their affordability and cost-effectiveness. AIM: To investigate how many drugs are in development for very rare conditions. METHODS: We defined very rare conditions as having a prevalence of <1:50,000, and identified pharmaceuticals in phase II, phase III trials or pre-registration for these conditions using commercial databases. RESULTS: We identified 42 very rare conditions with at least one drug in late-stage clinical development, with a total of 113 drugs in development (17 for at least two indications). Sixteen drugs were pre-registration, 29 were in phase III development, 65 were in phase II development, one drug was both pre-registration and phase II for different indications and two drugs were in both phase II and phase III trials for different indications. DISCUSSION: Not all the drugs in development will reach the market, but it is likely that a significant number will do so. Affordability and methods to assess cost-effectiveness will need debate and clear national policy for decision-makers to follow.

T-lymphocyte profiles in FIV-infected wild lions and pumas reveal CD4 depletion.

Feline immunodeficiency virus (FIV) is a lentivirus related to human immunodeficiency virus (HIV) that causes feline AIDS in the domestic cat (Felis catus). Serological surveys indicate that at least 25 other species of cat possess antibodies that cross-react with domestic cat FIV. Most infected nondomestic cat species are without major symptoms of disease. Long-term studies of FIV genome variation and pathogenesis reveal patterns consistent with coadaptation of virus and host in free-ranging FIV-Ple-infected African lions (Panthera leo) and FIV-Pco-infected pumas (Puma concolor) populations. This report examined correlates of immunodeficiency in wild and captive lions and pumas by quantifying CD5(+), CD4(+), and CD8(+) T-cell subsets. Free-ranging FIV-Ple-infected lions had immunofluorescence flow cytometry (IFC) profiles marked by a dramatic decline in CD4(+) subsets, a reduction of the CD4(+)/CD8(+) ratio, reduction of CD8(+)beta(high) cells, and expansion of the CD8(+)beta(low) subset relative to uninfected lions. An overall significant depletion in CD5(+) T-cells in seropositive lions was linked with a compensatory increase in total CD5(-) lymphocytes. The IFC profiles were altered significantly in 50% of the seropositive individuals examined. The FIV-Pco-infected pumas had a more generalized response of lymphopenia expressed as a significant decline in total lymphocytes, CD5(+) T-cells, and CD5(-) lymphocytes as well as a significant reduction in CD4(+) T-cells. Like lions, seropositive pumas had a significant decline in CD8(+)beta(high) cells but differed by not having compensatory expansion of CD8(+)beta(low) cells relative to controls. Results from FIV-infected lions and pumas parallel human and Asian monkey CD4(+) diminution in HIV and SIV infection, respectively, and suggest there may be unrecognized immunological consequences of FIV infection in these two species of large cats.

Tuberculosis in Tanzanian wildlife.

Bovine tuberculosis, caused by Mycobacterium bovis, is a pathogen of growing concern in free-ranging wildlife in Africa, but little is known about the disease in Tanzanian wildlife. Here, we report the infection status of Mycobacterium bovis in a range of wildlife species sampled from protected areas in northern Tanzania. M. bovis was isolated from 11.1% (2/18) migratory wildebeest (Connochaetes taurinus) and 11.1% (1/9) topi (Damaliscus lunatus) sampled systematically in 2000 during a meat cropping program in the Serengeti ecosystem, and from one wildebeest and one lesser kudu (Tragelaphus imberbis) killed by sport hunters adjacent to Tarangire National Park. A tuberculosis antibody enzyme immunoassay (EIA) was used to screen serum samples collected from 184 Serengeti lions (Panthera leo) and 19 lions from Ngorongoro Crater sampled between 1985 and 2000. Samples from 212 ungulates collected throughout the protected area network between 1998 and 2001 also were tested by EIA. Serological assays detected antibodies to M. bovis in 4% of Serengeti lions; one positive lion was sampled in 1984. Antibodies were detected in one of 17 (6%) buffalo (Syncerus caffer) in Tarangire and one of 41 (2%) wildebeest in the Serengeti. This study confirms for the first time the presence of bovine tuberculosis in wildlife of northern Tanzania, but further investigation is required to assess the impact on wildlife populations and the role of different wildlife species in maintenance and transmission.

Female lions can identify potentially infanticidal males from their roars.

Despite evidence from several bird, fish and mammal species that listeners can discriminate between the vocalizations of familiar and unfamiliar adult conspecifics, direct links between discriminatory abilities and fitness benefits have been difficult to identify. In free-ranging populations of African lions (Panthera leo), females with cubs face a substantial threat from one particular category of unfamiliar individuals: infanticidal males. Here we use playback experiments to demonstrate that females with cubs can distinguish immediately between roars from their own resident males (the fathers of the cubs) and those from unfamiliar, potentially infanticidal males. Although they remain relaxed when played roars from resident males, they immediately become agitated on hearing unfamiliar males and retreat rapidly with their cubs if the latter have reached about 4.5 months of age. These responses are not simply a function of the roarers being unfamiliar, for when played the roars of unfamiliar females, females with cubs consistently approach the loudspeaker. Furthermore, females often move toward the cubs in response to playbacks of unfamiliar males but not in response to playbacks of unfamiliar females or resident males. Our results suggest how females with cubs might, by quickly detecting and categorizing unfamiliar intruders within their territory, protect their cubs from infanticidal males and expel intruding females. Distinguishing between individuals on the basis of their vocal characteristics could therefore confer direct fitness benefits on discriminating lionesses.

Development of cooperative territoriality in juvenile lions.

African lions, Panthera leo, engage in many cooperative activities including hunting, care of young, and group territoriality, but the contribution of juvenile lions to these activities has never been documented. Here we present experimental evidence that juvenile lionesses make a gradual transition to group-territorial defence between weaning (8 months) and sexual maturity (42 months). When challenged by simulated intruders played from a loud-speaker, juvenile females (but not males) become progressively more likely to join the adult females in territorial defence with age, and their behaviour is affected by both the number of defending adults and the number of intruders. We interpret the ability of juveniles to assess relative numbers as an adaptation for assessing the risk of territorial conflict according to their own fighting ability, and the ability of their pride of successfully defend the territory. The difference between the sexes reflects the greater value of the natal territory to philopatric females. Adult females display a variety of strategies when defending the territory, including unconditional and conditional forms of cooperation. We show here that individuals display the rudiments of these strategies as juveniles.

Smooth muscle contractility. Effects of hypoxia.

Mechanical perturbation of smooth muscle provides information about the mechanical properties of its crossbridges. We have developed a method for identifying: (1) that normally cycling and very slowly cycling are sequentially activated, (2) the moment of this transition, and (3) the proportions of the two types of bridges recruited. Hypoxia decreases muscle shortening ability before isometric force. The former is due to depression of activity of both types of bridges.

Pulmonary arterial smooth muscle contractility in hypoxia-induced pulmonary hypertension.

The highly compliant low-resistance pulmonary vasculature is markedly altered with chronic hypoxia. Remodeling in response to hypoxia and/or hypertension involves hypertrophy and hyperplasia of smooth muscle and excessive deposition of connective tissue that likely contributes to the maintenance or exasperates the already elevated pulmonary arterial (PA) pressure. The purpose of this study was to investigate the effect of chronic hypoxia on the contractile properties of PA smooth muscle. Isometric and isotonic experiments were performed on excised PA rings from pulmonary hypertensive (induced by 14 days of hypoxia) Sprague-Dawley rats. A doubling of the vessel wall thickness occurred during the development of hypoxia-induced pulmonary hypertension. Functionally, there was a decrease in isometric stress (force to cross-sectional area ratio). No difference was detected in the velocity of shortening or in total shortening ability. This study provides evidence that, in addition to the morphological changes, changes in PA smooth muscle contractility also appear to play a role in the development and/or maintenance of hypoxia-induced pulmonary hypertension.

Damp housing and adult health: results from a lifestyle study in Worcester, England.

STUDY OBJECTIVE: To explore the relationship between damp housing and adult health using two separate measures of ill health and taking into account the confounding effects of health related lifestyles and social factors. DESIGN AND SETTING: Analysis of responses gathered in a cross sectional, postal questionnaire survey of a randomly selected sample of 5347 residents of Worcester. PARTICIPANTS: Altogether 2353 people aged 16 to 64 years responded to the survey (adjusted response 52%). RESULTS: Nine per cent of respondents lived in housing which they reported to be damp. Rates were highest among young women. People who lived in damp housing were more likely to report long standing illness, disability, or infirmity; the increased prevalence could not be attributed to any particular medical condition. Perceived ill health, as measured by the sleep, energy, and social isolation dimensions of the Nottingham Health Profile, was also more common in this group. These associations could not be explained by lifestyle factors; the relationship proved strongest among people in non-manual social classes living in owner occupied housing. The prevalence of ill health increased as the severity of dampness increased. CONCLUSION: Self reported damp housing and ill health in adults were strongly associated, most noticeably among people in non-manual social classes living in owner occupied housing. The association met many of the epidemiological criteria necessary for suggesting causality: alternative explanations are discussed.