RESUMEN

Cylicospirura Vevers, 1922 is a genus of gastrointestinal spirurid nematodes parasitizing mainly felid but also canid, hyaenid and dasyurid hosts. Presently, 11 species are recognized worldwide, of which 4, Cylicospirura subaequalis, Cylicospirura felinea, Cylicospirura crocutae and Cylicospirura pardalis, have been recorded from African carnivores. In the present study, we describe Cylicospirura phiri n. sp. from hyaenas, namely Crocuta crocuta (type host) in Zimbabwe and Hyaena hyaena in Cameroon. The new species is the second species in the genus with bicuspid teeth. Furthermore, it can be distinguished from its congeners by a combination of characters, such as the absence of accessory teeth, the length and shape of the muscular oesophagus, position of the nerve ring, deirids and excretory pore in relation to the muscular oesophagus, the position of the vulva, spicule length and the shape of the female tail. Additionally, based on new material, detailed morphological descriptions are provided for C. crocutae and C. pardalis whose original descriptions were based on fragmented material. The material from Felis lybica, currently deposited as C. subaequalis, is described as C. felinea. First-time scanning electron micrographs are presented for the 4 species confirmed in African carnivores.

RESUMEN

In human-dominated landscapes, quantifying ecosystem services in terms of economic benefits could contribute to establishing peaceful coexistence between humans and large carnivores. In this study, we estimated the monetary value of scavenging benefits provided by striped hyenas (Hyaena hyaena) in an anthropogenic landscape in the semi-arid region of Rajasthan, India. We converted the value of domestic livestock carcasses consumed by striped hyenas from opportunity costs to quantify the value of this important ecosystem service to local people. We determined the monetary value of carcass disposals using two methods, including (1) electric cremation, and (2) pyre burning of animal carcasses. To determine the minimum number of striped hyenas, present in the study area, we employed a photo-capture approach, and we used scat analysis to determine the livestock consumed by striped hyenas. We estimated that striped hyenas removed 23.13 tons (4.4 %) of livestock carcass waste from the total of 525.68 tons of waste generated per year in the Intensive Study Area (ISA). The annual monetary value of livestock carcass waste removal by striped hyenas in the ISA was estimated to be ~US$ 7095 for electric cremation and US$ 49,665 for pyre burning. Our study demonstrates the economic benefit of scavenging services provided by striped hyenas in areas where anthropogenic food is abundant. In such areas, as hyenas scavenge anthropogenic food, local communities benefit from waste management. Using alternative carcass disposal methods without striped hyenas would be expensive and likely environmentally damaging.

RESUMEN

In an ongoing study of the striped hyena (Hyaena hyaena), we observed that in the nine different females, alloparenting by the daughters of a previous litter was not uncommon and occurred on fifteen different occasions, twice with two helpers. Alloparenting persisted from when the cubs are approximately a month old until they reach the age when they go out foraging with their mothers at 10-12 months. Helpers perform most maternal duties, except suckling, even in the mother's presence. Helpers accrued indirect fitness and practiced parenting before reaching sexual maturity. Future studies must study the reproductive biology of the striped hyena in the wild throughout its geographic range to elucidate additional breeding properties that have not yet been identified. The continued persecution of striped hyenas and the lack of information about their breeding rituals and capabilities in the wild mean that this study of their different reproduction strategies, focusing on surrogate mothers, is of great conservation importance. The fact that we have found cooperative breeding in this solitary species suggests that there is much more to uncover of the enigmatic striped hyena in the wild.

RESUMEN

African large carnivores have undergone significant range and population declines over recent decades. Although conservation planning and the management of threatened species requires accurate assessments of population status and monitoring of trends, there is evidence that biodiversity monitoring may not be evenly distributed or occurring where most needed. Here, we provide the first systematic review of African large carnivore population assessments published over the last two decades (2000-2020), to investigate trends in research effort and identify knowledge gaps. We used generalised linear models (GLMs) and generalised linear mixed models (GLMMs) to identify taxonomic and geographical biases, and investigated biases associated with land use type and author nationality. Research effort was significantly biased towards lion (Panthera leo) and against striped hyaena (Hyaena hyaena), despite the latter being the species with the widest continental range. African wild dog (Lycaon pictus) also exhibited a negative bias in research attention, although this was partly explained by its relatively restricted distribution. The number of country assessments for a species was significantly positively associated with its geographic range in that country. Population assessments were biased towards southern and eastern Africa, particularly South Africa and Kenya. Northern, western, and central Africa were generally under-represented. Most studies were carried out in photographic tourism protected areas under government management, while non-protected and trophy hunting areas received less attention. Outside South Africa, almost half of studies (41%) did not include authors from the study country, suggesting that significant opportunities exist for capacity building in range states. Overall, large parts of Africa remain under-represented in the literature, and opportunities exist for further research on most species and in most countries. We develop recommendations for actions aimed at overcoming the identified biases and provide researchers, practitioners, and policymakers with priorities to help inform future research and monitoring agendas.

Asunto(s)

Canidae , Carnívoros , Hyaenidae , Leones , Animales , Especies en Peligro de Extinción , Sudáfrica

RESUMEN

We have investigated the relationship between spotted hyaenas in the south Namib Desert and large herbivorous prey and have summarized an updated overview of predator-prey relationships in this resource-limited arid environment. Over the 52-month study, we recorded the densities (#/km-2, ±SE) of the four local large herbivorous prey species: gemsbok (1.229, ±0.50), springbok (1.352, ±0.48), ostrich (0.648, ±0.23), and greater kudu (0.343, ±0.00). A fecal analysis was performed on 146 collected spotted hyaena scats, and prey items were identified and hairs cross-follicle analyzed to the species level. Spotted hyaena diet at the study area remained opportunistic with 240 identified prey items representing eight differing prey species being recorded, ranging from ostrich eggs to large ungulates. The Ivlev's Electivity Index was used to determine which large herbivorous prey was most selected for. Although gemsbok had a higher representation of prey items in the sampled scats, all sampled large herbivorous prey species scored below 0 and are thus generally avoided in relation to their availability in the environment. If any prey preferences are expressed by spotted hyaena in the Namib, it can be presumed to be a nonsampled prey species. We therefore promote further detailed investigations into all other prey species present, and seasonal variations of prey densities and scat sampling, within the study environment.

RESUMEN

Apex predators play important roles in ecosystem functioning and, where they coexist, intraguild interactions can have profound effects on trophic relationships. Interactions between predators range from intraguild predation and competition to facilitation through scavenging opportunities. Despite the increased availability of fine-scale GPS data, the determinants and outcomes of encounters between apex predators remain understudied. We used simultaneous GPS data from collared spotted hyaenas (Crocuta crocuta) and African lions (Panthera leo) in Hwange National Park, Zimbabwe, to determine the environmental conditions of the encounters between the two species, which species provoked the encounter, and which species dominated the encounter. Our results show that encounters between hyaenas and lions are mostly resource-related (over a carcass or around waterholes). In the wet season, encounters mainly occur at a carcass, with lions being dominant over its access. In the dry season, encounters mainly occur in the absence of a carcass and near waterholes. Movements of hyaenas and lions before, during, and after these dry-season encounters suggest two interference scenarios: a passive interference scenario whereby both predators would be attracted to waterholes but lions would leave a waterhole used by hyaenas because of prey disturbance, and an active interference scenario whereby hyaenas would actively chase lions from waterhole areas, which are prime hunting grounds. This study highlights the seasonal dynamics of predator interactions and illustrates how the relative importance of negative interactions (interference competition during the dry season) and positive interactions (scavenging opportunities during the wet season) shifts over the course of the year.

Asunto(s)

Ecosistema , Leones , Animales , Conducta Predatoria , Estaciones del Año

RESUMEN

Striped hyenas (Hyaena hyaena) are extremely rare in Nepal, and only a few people have studied them in their natural forest and grassland habitat. Their rarity is due to anthropogenic pressures such as hunting, habitat modification, being killed on roads, and depletion of their natural prey. Here, we studied the feeding ecology of hyenas in lowland, Nepal. We employed an opportunistic sampling to collect hyena scats in a range of habitats and the line transect sampling to identify the prey of the hyena in the study site. We collected 68 hyena scats between 2015 and 2018. Most of the hyena scat (39.7%) was found in the Churia Hill forest followed by riverbed (26.4%), mixed forest (14.7%), Sal (Shorea robusta)-dominated forest (11.7%), and grassland area (7.3%). We found eleven mammalian prey species, plants, and some unidentified items in the hyena scats. The frequency of occurrence and relative biomass of the medium-sized wild boar (Sus scrofa) were higher than other smaller prey species such as hare (Lepus nigricollis) and rhesus macaque (Macaca mulatta). Similarly, the proportion of large prey species such as nilgai (Boselaphus tragocamelus) in the hyena diet was lower compared with wild boar, hares, and rhesus macaques indicating medium-sized wild boar is the most preferred prey species. Livestock contributed 17.3% of the total dietary biomass. Domesticated species such as goats, sheep, cows, and even dogs were found in the diet of hyenas. Predation of livestock by hyenas could cause conflict, especially if this ongoing issue continues in the future. Rather, more conservation effort is required in lowland areas of Nepal to protect the hyenas' natural prey species, particularly in wildlife habitats to reduce the lure of taking domestic livestock. Similarly, conservation education at the local level and active involvement of government authorities in the conservation of this species might be helpful to mitigate human-hyena conflict in the human-dominated landscape.

RESUMEN

The spotted hyaena (Crocuta crocuta) is a unique species, even amongst the Hyaenidae. Extreme clitoral development in female spotted hyaenas challenges aspects of the accepted framework of sexual differentiation and reproductive function. They lack a vulva and instead urinate, copulate and give birth through a single, long urogenital canal that traverses a clitoris superficially resembling a penis. Recent and historical evidence is reviewed to describe our changing understanding of the biology of this species. Expanding upon observations from hyaenas in nature, much has been learned from studies utilising the captive colony at the University of California, Berkeley. The steroid environment of pregnancy is shaped by placental androgen and oestrogen secretion and a late gestational increase in sex hormone binding globulin, the regulated expression and steroid-binding characteristics of which are unique within the Hyaenidae. While initial external genital development is largely free of androgenic influence, the increase in testosterone concentrations in late gestation influences foetal development. Specifically, anti-androgen (AA) treatment of pregnant females reduced the developmental influence of androgens on their foetuses, resulting in reduced androstenedione concentrations in young females and easier birth through a 'feminised' clitoris, but precluded intromission and mating by 'feminised' male offspring, and altered social interactions. Insight into the costs and benefits of androgen exposure on spotted hyaena reproductive development, endocrinology and behaviour emphasises the delicate balance that sustains reproductive success, forces a re-evaluation of how we define masculine vs feminine sexual characteristics, and motivates reflection about the representative value of model species.

Asunto(s)

Genitales Femeninos , Genitales Masculinos , Hormonas Esteroides Gonadales/fisiología , Hyaenidae , Reproducción/fisiología , Diferenciación Sexual/fisiología , Andrógenos/fisiología , Animales , Estrógenos/fisiología , Femenino , Genitales Femeninos/anatomía & histología , Genitales Femeninos/embriología , Genitales Femeninos/crecimiento & desarrollo , Genitales Masculinos/anatomía & histología , Genitales Masculinos/embriología , Genitales Masculinos/crecimiento & desarrollo , Hyaenidae/anatomía & histología , Hyaenidae/embriología , Hyaenidae/fisiología , Masculino , Embarazo , Globulina de Unión a Hormona Sexual/fisiología , Conducta Sexual Animal/fisiología

RESUMEN

Understanding the drivers promoting sociality over solitariness in animal species is imperative for predicting future population trends and informing conservation and management. In this study we investigate the social structure of a desert dwelling population of striped hyena Hyaena hyaena. This species is historically regarded as strictly solitary albeit being the least studied of the extant Hyaenids. Accumulating evidence regarding the frequency of social interactions suggests a revision of striped hyena social structure is required. We hypothesized that striped hyena has a social structure that is more complex than expected for a strictly solitary species. For that end, we deployed an array of camera-traps in a remote desert region in Israel, and compared observed frequencies of striped hyena co-occurrence against null models to test whether hyena co-occurred more than expected by chance. Seven adults were (re)captured by our camera-traps in 49 different instances over 83 tracking days. Of these, 6 exhibited shared space-use around a scarce, isolated perennial water source. Five of them, co-occurred with other hyena (in 3 instances) significantly more frequent than expected by chance (and that timing suggests reproduction is unlikely to be the driving factor). Our findings substantiate evidence of complex social structure in striped hyena, highlight the importance of a scarce resource in space-use and sociality, and provide a baseline for future research of striped hyena social structure. We suggest that similar methods be employed to evaluate social structure in other "solitary species" to better understand their social dynamics.

RESUMEN

Chemical immobilisation is an integral component for the conservation of wild animals and can be stressful if proper protocols are not administered. References on the immobilisation of Arabian striped hyaena (Hyaena hyaena sultana) are scarce. The current study was designed to evaluate the physiological and clinical responses of Arabian striped hyaena, immobilised with ketamine-medetomidine (KM) and ketamine-xylazine (KX); and to compare immobilisation effectiveness of the two combinations in a cross-sectional clinical study. A total of 15 (six males, nine females) (semi-) captive and adult Arabian striped hyaena with an average weight of 31.39 ± 0.36 kg were immobilised 50 times for annual vaccination and translocation purposes from January 2014 till March 2018 on Sir Bani Yas Island, United Arab Emirates. A total of 34 immobilisations were executed with (Mean ± SE) 2.27 ± 0.044 mg/kg ketamine and 0.04 ± 0.001 mg/kg medetomidine; while 16 with 4.95 ± 0.115 mg/kg ketamine and 0.99 ± 0.023 mg/kg xylazine. The drugs were remotely delivered intramuscular. The evaluation of physiological and clinical parameters included monitoring of vital signs through pulse oximetry, blood gas analysis of arterial blood through Istat blood gas analyser, and blood biochemistry and haematology. The quality of induction, anaesthesia and recovery was also assessed. Atipamezole (0.21 ± 0.003 mg/kg) was used to antagonise the effects of KM and 0.09 ± 0.003 mg/kg atipamezole or by 0.23 ± 0.006 mg/kg yohimbine for KX. Data were analysed using the general linear model and inferential statistics. KM was more effective in induction (scores; KM = 1.41 ± 0.10; KX = 1.31 ± 0.12), anaesthesia (KM = 1.00 ± 0.00; KX = 2.0 ± 0.0) and recovery (KM = 1.76 ± 0.15; KX = 2.69 ± 0.12) phases as compared to KX. There was a significant difference (P < 0.05) amongst the two combinations for anaesthesia time (KM = 59.5 ± 2.41; KX = 49.25 ± 1.31 min.), time to stand after reversal (KM = 4.91 ± 0.60; KX = 10.38 ± 1.48 min.) and full loss of the signs of anaesthetics (KM = 12.32 ± 1.37; KX = 21.25 ± 2.16 min.) along with rectal temperature (KM = 37.58 ± 0.29; KX = 36.00 ± 0.68 °C), pulse rate (KM = 50.46 ± 1.90; KX = 61.14 ± 2.79 beats/min), respiration rate (KM = 29.44 ± 0.99; KX = 23.80 ± 1.57 breaths/min.) and partial pressure of oxygen (KM = 89.59 ± 1.34; KX = 82.06 ± 3.92%). The blood oxygen saturation by oximeter indicated hypoxaemia in KX (82.06 ± 3.92), supported by the data from blood gas analyser. KM combination was more suitable for the immobilisation of Arabian striped hyaena, providing a better quality of induction, anaesthesia and recovery compared to KX. However, we strongly suggest further investigation to see the effects of oxygen supplementation for the compensation of hypoxaemia.

RESUMEN

Both domestic and wild carnivore species are commonly diagnosed with rabies virus (RABV) infection in South Africa. Although the majority of confirmed rabies cases in wild carnivore species are reported from the yellow mongoose (Cynictis penicillata), the rest are from other wild carnivores including the highly endangered wild dog (Lycaon pictus). Lyssavirus infection was confirmed in two wild dogs and a spotted hyaena (Crocuta crocuta) in the Madikwe Game Reserve, North West province in South Africa, in 2014 and 2015, using a direct fluorescent antibody test and immunohistochemistry. There had been no new wild dog introductions to the Madikwe Game Reserve for many years and the wild dogs were last vaccinated against rabies approximately 11 years prior to the incident. The first euthanised wild dog was the last surviving of a break-away pack of 6, and the second was the last of a larger pack of 18, the rest of which died with no carcasses being found or carcasses too decomposed for sampling. Subsequent antigenic typing of the lyssaviruses indicated that they were canid RABVs. The RABVs originating from 22 wild carnivore species, 7 dogs, and a caprine, mostly from the North West province, were genetically characterised by targeting a partial region of the nucleoprotein gene. The nucleotide sequence analyses of these viruses and two previously characterised RABVs confirmed that the outbreak viruses were also canid rabies, phylogenetically clustering with virus isolates originating from black-backed jackals recovered between 2012 and 2015 from the North West province, and domestic dogs from neighbouring communal areas. The source(s) of the mortalities and possible reservoir host(s) for the virus could only be speculated upon from data on specific predator numbers, movements and behaviour, kills, park management and the changing environmental ecology, which were monitored closely in Madikwe over several years. The most likely rabies sources were from boundary fence contacts between wild carnivores within the park, with domestic dogs or cats and/or naturally occurring wild carnivores outside the park. The associated risk of zoonotic infection and threat to important and endangered predators may be mitigated through regional rabies control primarily in domestic dogs and cats, as well as by preventative vaccination of at-risk park employees and their pets. The importance of ongoing prophylactic rabies protection by regular vaccination of highly endangered wildlife carnivores and the submission of carcasses for rabies diagnosis of any wild or domestic animals behaving uncharacteristically or found dead is emphasised.

Asunto(s)

Animales Salvajes/virología , Canidae/virología , Hyaenidae/virología , Infecciones por Rhabdoviridae/veterinaria , Animales , Animales de Zoológico , Encéfalo/virología , Brotes de Enfermedades/prevención & control , Perros , Especies en Peligro de Extinción , Humanos , Inmunoquímica , Lyssavirus/aislamiento & purificación , Masculino , Rabia , Vacunas Antirrábicas , Infecciones por Rhabdoviridae/diagnóstico , Infecciones por Rhabdoviridae/epidemiología , Infecciones por Rhabdoviridae/prevención & control , Sudáfrica/epidemiología , Zoonosis/prevención & control

RESUMEN

Reports of livestock depredation by large predators were systematically collected at three study sites in northwestern Zimbabwe from 2008-2013. We recorded 1,527 incidents (2,039 animals killed and 306 injured). Lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) were mostly responsible, and cattle and donkeys most frequently attacked. Patterns of predation were variable among study sites. Nevertheless, some overall patterns were apparent. Predators selected livestock close to the size of their preferred wild prey, suggesting behaviours evolved to optimise foraging success may determine the domestic species primarily preyed upon. Most attacks occurred when livestock were roaming outside and away from their 'home' protective enclosures at night. Hyaena attacks were largely nocturnal; lions and leopards (Panthera pardus) were more flexible, with attacks occurring by day and at night. Livestock fitted with bells suffered a disproportionate number of attacks; the sound of bells appears to have conditioned predators to associate the sound with foraging opportunities. Lion and hyaena attacks on cattle were more frequent in the wet season suggesting that seasonal herding practices may result in cattle vulnerability. Only a small proportion of conflict incidents were reported to wildlife management officials with a bias towards lion predation events, potentially prejudicing conflict management policies. Predation on domestic stock involves an intricate interplay between predator behaviour and ecology on the one hand and human behaviour and husbandry practices on the other. Our data suggest that improved livestock husbandry (supervision of grazing animals, protection at night in strong enclosures) would greatly reduce livestock depredation.

RESUMEN

Food caching is a common strategy used by a diversity of animals, including carnivores, to store and/or secure food. Despite its prevalence, the drivers of caching behaviour, and its impacts on individuals, remain poorly understood, particularly for short-term food cachers. Leopards Panthera pardus exhibit a unique form of short-term food caching, regularly hoisting, storing and consuming prey in trees. We explored the factors motivating such behaviour among leopards in the Sabi Sand Game Reserve, South Africa, associated with four not mutually exclusive hypotheses: food-perishability, consumption-time, resource-pulse and kleptoparasitism-avoidance. Using data from 2032 prey items killed by 104 leopards from 2013 to 2015, we built generalized linear mixed models to examine how hoisting behaviour, feeding time and the likelihood of a kill being kleptoparasitized varied with leopard sex and age, prey size and vulnerability, vegetation, elevation, climate, and the immediate and long-term risk posed by dominant competitors. Leopards hoisted 51% of kills. They were more likely to hoist kills of an intermediate size, outside of a resource pulse and in response to the presence of some competitors. Hoisted kills were also fed on for longer than non-hoisted kills. At least 21% of kills were kleptoparasitized, mainly by spotted hyaenas Crocuta crocuta. Kills were more likely to be kleptoparasitized at lower temperatures and if prey were larger, not hoisted, and in areas where the risk of encountering hyaenas was greatest. Female leopards that suffered higher rates of kleptoparasitism exhibited lower annual reproductive success than females that lost fewer kills. Our results strongly support the kleptoparasitism-avoidance hypothesis and suggest hoisting is a key adaptation that enables leopards to coexist sympatrically with high densities of competitors. We further argue that leopards may select smaller-sized prey than predicted by optimal foraging theory, to balance trade-offs between kleptoparasitic losses and the energetic gains derived from killing larger prey. Although caching may provide the added benefits of delaying food perishability and enabling consumption over an extended period, the behaviour primarily appears to be a strategy for leopards, and possibly other short-term cachers, to reduce the risks of kleptoparasitism.

Asunto(s)

Cadena Alimentaria , Hyaenidae/fisiología , Panthera/fisiología , Conducta Predatoria , Animales , Femenino , Masculino , Sudáfrica

RESUMEN

The objective of our study was identification and molecular characterization of piroplasms and rickettsias occurring in brown (Parahyaena brunnea) and spotted hyaenas (Crocuta crocuta) from various localities in Namibia and South Africa. Whole blood (n = 59) and skin (n = 3) specimens from brown (n = 15) and spotted hyaenas (n = 47) were screened for the presence of Babesia, Theileria, Ehrlichia and Anaplasma species using the reverse line blot (RLB) hybridization technique. PCR products of 52/62 (83.9%) of the specimens hybridized only with the Theileria/Babesia genus-specific probes and not with any of the species-specific probes, suggesting the presence of a novel species or variant of a species. No Ehrlichia and/or Anaplasma species DNA could be detected. A parasite 18S ribosomal RNA gene of brown (n = 3) and spotted hyaena (n = 6) specimens was subsequently amplified and cloned, and the recombinants were sequenced. Homologous sequence searches of databases indicated that the obtained sequences were most closely related to Babesia lengau, originally described from cheetahs (Acinonyx jubatus). Observed sequence similarities were subsequently confirmed by phylogenetic analyses which showed that the obtained hyaena sequences formed a monophyletic group with B. lengau, B abesia conradae and sequences previously isolated from humans and wildlife in the western USA. Within the B. lengau clade, the obtained sequences and the published B. lengau sequences were grouped into six distinct groups, of which groups I to V represented novel B. lengau genotypes and/or gene variants. We suggest that these genotypes cannot be classified as new Babesia species, but rather as variants of B. lengau. This is the first report of occurrence of piroplasms in brown hyaenas.

Asunto(s)

Anaplasma/clasificación , Babesia/clasificación , Ehrlichia/clasificación , Hyaenidae/parasitología , Theileria/clasificación , Anaplasma/genética , Anaplasma/aislamiento & purificación , Animales , Animales Salvajes/microbiología , Animales Salvajes/parasitología , Babesia/genética , Babesia/aislamiento & purificación , Babesiosis/epidemiología , ADN Bacteriano/genética , ADN Protozoario/genética , Ehrlichia/genética , Ehrlichia/aislamiento & purificación , Genotipo , Namibia , Técnicas de Amplificación de Ácido Nucleico , Hibridación de Ácido Nucleico , Filogenia , Reacción en Cadena de la Polimerasa , ARN Ribosómico 18S/genética , Homología de Secuencia , Sudáfrica , Theileria/genética , Theileria/aislamiento & purificación

RESUMEN

Was the 1993/1994 fatal canine distemper virus (CDV) epidemic in lions and spotted hyaenas in the Serengeti ecosystem caused by the recent spillover of a virulent domestic dog strain or one well adapted to these noncanids? We examine this question using sequence data from 13 'Serengeti' strains including five complete genomes obtained between 1993 and 2011. Phylogenetic and haplotype network analyses reveal that strains from noncanids during the epidemic were more closely related to each other than to those from domestic or wild canids. All noncanid 'Serengeti' strains during the epidemic encoded: (1) one novel substitution G134S in the CDV-V protein; and (2) the rare amino acid combination 519I/549H at two sites under positive selection in the region of the CDV-H protein that binds to SLAM (CD 150) host cell receptors. Worldwide, only a few noncanid strains in the America II lineage encode CDV-H 519I/549H. All canid 'Serengeti' strains during the epidemic coded CDV-V 134G, and CDV-H 519R/549Y, or 519R/549H. A functional assay of cell entry revealed the highest performance by CDV-H proteins encoding 519I/549H in cells expressing lion SLAM receptors, and the highest performance by proteins encoding 519R/549Y, typical of dog strains worldwide, in cells expressing dog SLAM receptors. Our findings are consistent with an epidemic in lions and hyaenas caused by CDV variants better adapted to noncanids than canids, but not with the recent spillover of a dog strain. Our study reveals a greater complexity of CDV molecular epidemiology in multihost environments than previously thought.

Asunto(s)

Canidae/virología , Virus del Moquillo Canino/genética , Evolución Molecular , Filogenia , Adaptación Biológica/genética , Secuencia de Aminoácidos , Animales , Animales Salvajes/virología , Moquillo/epidemiología , Ecosistema , Haplotipos , Especificidad del Huésped , Hyaenidae/virología , Leones/virología , Modelos Genéticos , Epidemiología Molecular , ARN Viral/genética , Selección Genética , Análisis de Secuencia de ARN , Tanzanía

RESUMEN

Theoretically intelligence should evolve to help animals solve specific types of problems posed by the environment, but it remains unclear how environmental complexity or novelty facilitates the evolutionary enhancement of cognitive abilities, or whether domain-general intelligence can evolve in response to domain-specific selection pressures. The social complexity hypothesis, which posits that intelligence evolved to cope with the labile behaviour of conspecific group-mates, has been strongly supported by work on the sociocognitive abilities of primates and other animals. Here we review the remarkable convergence in social complexity between cercopithecine primates and spotted hyaenas, and describe our tests of predictions of the social complexity hypothesis in regard to both cognition and brain size in hyaenas. Behavioural data indicate that there has been remarkable convergence between primates and hyaenas with respect to their abilities in the domain of social cognition. Furthermore, within the family Hyaenidae, our data suggest that social complexity might have contributed to enlargement of the frontal cortex. However, social complexity failed to predict either brain volume or frontal cortex volume in a larger array of mammalian carnivores. To address the question of whether or not social complexity might be able to explain the evolution of domain-general intelligence as well as social cognition in particular, we presented simple puzzle boxes, baited with food and scaled to accommodate body size, to members of 39 carnivore species housed in zoos and found that species with larger brains relative to their body mass were more innovative and more successful at opening the boxes. However, social complexity failed to predict success in solving this problem. Overall our work suggests that, although social complexity enhances social cognition, there are no unambiguous causal links between social complexity and either brain size or performance in problem-solving tasks outside the social domain in mammalian carnivores.

RESUMEN

Calls that catalyse group defence, as in the mobbing of predators, appear to facilitate cooperation by recruiting receivers to act collectively. However, even when such signals reliably precede cooperative behaviour, the extent to which the calls function as recruitment signals is unclear. Calls might simply arouse listeners' attention, setting off a cascade of independent responses to the threat. By contrast, they might convey information, for example, about signaller identity and the nature of a threat that affects receivers' decisions to participate. We explored this distinction by investigating a possible long-distance recruitment call used by spotted hyaenas. These social carnivores live in fission-fusion clans and individuals disperse widely within their territories. Putative recruitment calls must therefore attract receivers that are distant from the inciting threat and free to opt out of risky collective aggression. Hyaenas compete with lions over food, and neighbouring clans sometimes engage in violent border clashes. These high-stakes contests are decided based on numerical asymmetries, so hyaenas can only protect critical resources if the dispersed clan can converge quickly at conflict sites. We recorded and analysed whoop bouts produced in multiple contexts and found that bouts produced in response to signs of lion-hyaena conflict had shorter inter-whoop intervals than spontaneous 'display' bouts. In subsequent field playback experiments, resting hyaenas were significantly more likely to move in response to 'recruitment' bouts with shortened intervals than to otherwise identical 'display' bouts. Whereas only stimulus type predicted movement, lower-ranked subjects responded most quickly, perhaps because their feeding opportunities depend on arriving early at any kill site. Results demonstrate that hyaenas possess a signal that can reliably recruit allies across long distances, despite moderating effects of individual circumstances on the strength of receivers' responses.

RESUMEN

We provide the first genetic sequence data for a Dipylidium species from a wild carnivore plus an analysis of the effects of ecological, demographic, physiological and behavioural factors on Dipylidium sp. infection prevalence in a social carnivore, the spotted hyaena (Crocuta crocuta), in the Serengeti National Park, Tanzania. Our sequence data from a mitochondrial gene fragment (1176 base pair long) had a similarity of between 99% and 89% to Dipylidium caninum. We determined infection prevalence in 146 faecal samples from 124 known animals in three social groups (termed clans) using molecular screening and Dipylidium proglottid presence. Our analysis revealed significantly higher infection prevalence in juveniles (55%) than adults (15.8%), indicating that predominantly juveniles maintained infection in clans. The likelihood of infection in juveniles significantly: (1) increased as the number of adults and older juveniles (>6 months) at communal dens increased, implying a positive relationship between this factor and the size of the intermediate host (probably a flea species) population at communal dens; (2) decreased as the number of younger juveniles (<6 months) increased, suggesting that the chance of susceptible juveniles ingesting infected fleas during self-grooming declined as the number of infected fleas per younger juvenile declined; and (3) decreased during periods of low prey abundance in clan territories when an increased reliance on long-distances foraging excursions reduces the number of clan members visiting communal dens, possibly resulting in a decline in flea populations at dens. Long-distance foraging also increases the intervals (in days) between nursing visits by lactating females to their offspring. Lengthy intervals between milk intake by infected juveniles may reduce adult Dipylidium fecundity and hence decrease infection prevalence in the den flea population. Our study provides useful insights into Dipylidium epidemiology in a social carnivore population subject to large fluctuations in prey abundance.