Coccidiosis in the European badger, Meles meles in Wytham Woods: infection and consequences for growth and survival

A One-Year Retrospective Analysis of Viral and Parasitological Agents in Wildlife Animals Admitted to a First Aid Hospital

This study aimed to provide information on the presence and frequency of viral and parasitic agents in wildlife presented to a Veterinary Teaching Hospital in 2020-2021. Serum and faecal samples were collected from 50 rescued animals (roe deer, fallow deer, foxes, badgers, pine martens, and porcupines) and examined by serological, molecular, and parasitological techniques. Transtracheal wash (TTW) was also collected post-mortem from roe deer. Overall, the results of the different techniques showed infections with the following viral and parasitic agents: Bovine Viral Diarrhea Virus, Small Ruminant Lentiviruses, Kobuvirus, Astrovirus, Canine Adenovirus 1, Bopivirus, gastrointestinal strongyles, Capillaria, Ancylostomatidae, Toxocara canis, Trichuris vulpis, Hymenolepis, Strongyloides, Eimeria, Isospora, Dictyocaulus, Angiostrongylus vasorum, Crenosoma, Dirofilaria immitis, Neospora caninum, Giardia duodenalis, and Cryptosporidium. Sequencing (Tpi locus) identified G. duodenalis sub-assemblages AI and BIV in one roe deer and one porcupine, respectively. Adult lungworms collected from the TTW were identified as Dictyocaulus capreolus (COX1 gene). This is the first molecular identification of G. duodenalis sub-assemblage AI and D. capreolus in roe deer in Italy. These results show a wide presence of pathogens in wild populations and provide an overview of environmental health surveillance.

Early-life seasonal, weather and social effects on telomere length in a wild mammal

Early-life environmental conditions can provide a source of individual variation in life-history strategies and senescence patterns. Conditions experienced in early life can be quantified by measuring telomere length, which can act as a biomarker of survival probability in some species. Here, we investigate whether seasonal changes, weather conditions and group size are associated with early-life and/or early-adulthood telomere length in a wild population of European badgers (Meles meles). We found substantial intra-annual changes in telomere length during the first 3 years of life, where within-individual effects showed shorter telomere lengths in the winter following the first spring and a trend for longer telomere lengths in the second spring compared to the first winter. In terms of weather conditions, cubs born in warmer, wetter springs with low rainfall variability had longer early-life (3-12 months old) telomeres. Additionally, cubs born in groups with more cubs had marginally longer early-life telomeres, providing no evidence of resource constraint from cub competition. We also found that the positive association between early-life telomere length and cub survival probability remained when social and weather variables were included. Finally, after sexual maturity, in early adulthood (i.e., 12-36 months) we found no significant association between same-sex adult group size and telomere length (i.e., no effect of intrasexual competition). Overall, we show that controlling for seasonal effects, which are linked to food availability, is important in telomere length analyses, and that variation in telomere length in badgers reflects early-life conditions and also predicts first year cub survival.

Zoonotic Giardia duodenalis Genotypes and Other Gastrointestinal Parasites in a Badger Population Living in an Anthropized Area of Central Italy

The Eurasian badger (Meles meles) is widespread in Italy and occupies different habitats. The occurrence and species of gastrointestinal parasites were evaluated in a free-ranging badger population living in a highly anthropic area in central Italy. A total of 43 fecal samples were examined using the flotation test, the Mini-FLOTAC and Baermann techniques, and a rapid immunoassay for the detection of Giardia duodenalis and Cryptosporidium spp. fecal antigens. Molecular investigations were also performed that aimed at identifying Giardia genotypes. Overall, 37/43 samples (86%) were found positive. Specifically, 48.8% (21 samples) were positive for G.duodenalis, 23.2% (10/43) for Cryptosporidium spp., and 7% (3/43) for coccidian oocysts. Strongyloides sp. nematode larvae were detected in 3/43 samples (7%). Ascarid (1/43, 2.3%), capillariid (1/43, 2.3%), and strongyle-type eggs (76.7%, 33/43) were also identified. Among the 11 readable sequences of samples that were positive for G. duodenalis by end-point PCR (18/21), the zoonotic assemblage A sub-assemblage AII and mixed assemblage A and B were identified. This is the first report of zoonotic G. duodenalis genotypes in the Eurasian badger. Moreover, most of identified parasites have zoonotic potential and/or potential impact on the population health of wild badgers and other wild and domestic animals.

Patterns of Genital Tract Mustelid Gammaherpesvirus 1 (Musghv-1) Reactivation Are Linked to Stressors in European Badgers (Meles Meles)

Gammaherpesvirus reactivation can promote diseases or impair reproduction. Understanding reactivation patterns and associated risks of different stressors is therefore important. Nevertheless, outside the laboratory or captive environment, studies on the effects of stress on gammaherpesvirus reactivation in wild mammals are lacking. Here we used Mustelid gammaherpesvirus 1 (MusGHV-1) infection in European badgers (Meles meles) as a host-pathogen wildlife model to study the effects of a variety of demographic, physiological and environmental stressors on virus shedding in the genital tract. We collected 251 genital swabs from 150 free-ranging individuals across three seasons and screened them for the presence of MusGHV-1 DNA using PCR targeting the DNA polymerase gene. We explored possible links between MusGHV-1 DNA presence and seven variables reflecting stressors, using logistic regression analysis. The results reveal different sets of risk factors between juveniles and adults, likely reflecting primary infection and reactivation. In adults, virus shedding was more likely in badgers in poorer body condition and younger than 5 years or older than 7; while in juveniles, virus shedding is more likely in females and individuals in better body condition. However, living in social groups with more cubs was a risk factor for all badgers. We discuss possible explanations for these risk factors and their links to stress in badgers.

Negative density-dependent parasitism in a group-living carnivore

Animals living at high population densities commonly experience greater exposure to disease, leading to increased parasite burdens. However, social animals can benefit immunologically and hygienically from cooperation, and individuals may alter their socio-spatial behaviour in response to infection, both of which could counteract density-related increases in exposure. Consequently, the costs and benefits of sociality for disease are often uncertain. Here, we use a long-term study of a wild European badger population (Meles meles) to investigate how within-population variation in host density determines infection with multiple parasites. Four out of five parasite taxa exhibited consistent spatial hotspots of infection, which peaked among badgers living in areas of low local population density. Combined movement, survival, spatial and social network analyses revealed that parasite avoidance was the likely cause of this negative density dependence, with possible roles for localized mortality, encounter-dilution effects, and micronutrient-enhanced immunity. These findings demonstrate that animals can organize their societies in space to minimize parasite infection, with important implications for badger behavioural ecology and for the control of badger-associated diseases.

Estimation of environmental, genetic and parental age at conception effects on telomere length in a wild mammal

Understanding individual variation in fitness-related traits requires separating the environmental and genetic determinants. Telomeres are protective caps at the ends of chromosomes that are thought to be a biomarker of senescence as their length predicts mortality risk and reflect the physiological consequences of environmental conditions. The relative contribution of genetic and environmental factors to individual variation in telomere length is, however, unclear, yet important for understanding its evolutionary dynamics. In particular, the evidence for transgenerational effects, in terms of parental age at conception, on telomere length is mixed. Here, we investigate the heritability of telomere length, using the 'animal model', and parental age at conception effects on offspring telomere length in a wild population of European badgers (Meles meles). Although we found no heritability of telomere length and low evolvability (<0.001), our power to detect heritability was low and a repeatability of 2% across individual lifetimes provides a low upper limit to ordinary narrow-sense heritability. However, year (32%) and cohort (3%) explained greater proportions of the phenotypic variance in telomere length, excluding qPCR plate and row variances. There was no support for cross-sectional or within-individual parental age at conception effects on offspring telomere length. Our results indicate a lack of transgenerational effects through parental age at conception and a low potential for evolutionary change in telomere length in this population. Instead, we provide evidence that individual variation in telomere length is largely driven by environmental variation in this wild mammal.

Effects of Mustelid gammaherpesvirus 1 (MusGHV-1) Reactivation in European Badger (Meles meles) Genital Tracts on Reproductive Fitness

Reactivation of latent Gammaherpesvirus in the genital tract can lead to reproductive failure in domestic animals. Nevertheless, this pathophysiology has not received formal study in wild mammals. High prevalence of Mustelid gammaherpesvirus 1 (MusGHV-1) DNA detected in the genital tracts of European badgers (Meles meles) implies that this common pathogen may be a sexual transmitted infection. Here we used PCR to test MusGHV-1 DNA prevalence in genital swabs collected from 144 wild badgers in Ireland (71 males, 73 females) to investigate impacts on male fertility indicators (sperm abundance and testes weight) and female fecundity (current reproductive output). MusGHV-1 reactivation had a negative effect on female reproduction, but not on male fertility; however males had a higher risk of MusGHV-1 reactivation than females, especially during the late-winter mating season, and genital MusGHV-1 reactivation differed between age classes, where 3–5 year old adults had significantly lower reactivation rates than younger or older ones. Negative results in foetal tissues from MusGHV-1 positive mothers indicated that cross-placental transmission was unlikely. This study has broader implications for how wide-spread gammaherpesvirus infections could affect reproductive performance in wild Carnivora species.

Social effects on age-related and sex-specific immune cell profiles in a wild mammal

Evidence for age-related changes in innate and adaptive immune responses is increasing in wild populations. Such changes have been linked to fitness, and knowledge of the factors driving immune response variation is important for understanding the evolution of immunity. Age-related changes in immune profiles may be owing to factors such as immune system development, sex-specific behaviour and responses to environmental conditions. Social environments may also contribute to variation in immunological responses, for example, through transmission of pathogens and stress arising from resource and mate competition. Yet, the impact of the social environment on age-related changes in immune cell profiles is currently understudied in the wild. Here, we tested the relationship between leukocyte cell composition (proportion of neutrophils and lymphocytes [innate and adaptive immunity, respectively] that were lymphocytes) and age, sex and group size in a wild population of European badgers (Meles meles). We found that the proportion of lymphocytes in early life was greater in males in smaller groups compared to larger groups, but with a faster age-related decline in smaller groups. By contrast, the proportion of lymphocytes in females was not significantly related to age or group size. Our results provide evidence of sex-specific age-related changes in immune cell profiles in a wild mammal, which are influenced by the social environment.

Synergistic effects of predation and parasites on the overwinter survival of root voles

Predators and parasites have been important extrinsic factors influencing the fluctuation of small mammal populations. They can have non-additive effects on a shared group of preys or hosts, which can have important consequences for population dynamics. However, experimental studies incorporating the interactions between predation and parasites are scarce in small mammal populations. Here we systematically examined the synergistic effects of predators and coccidian parasites interaction on overwinter survival and likely mechanisms underlying the synergistic effects in the root vole (Microtus oeconomus). Our aim was to test the general hypothesis that predators and coccidia interact synergistically to decrease overwinter survival of root voles through mediating vole's physiological traits and body conditions. We carried out a factorial experimental design, by which we manipulated the predator exclusion in combination with the parasitic removal in enclosures, and then measured fecal corticosterone metabolite (FCM) levels, immunocompetence, and body conditions in captured animals via repeated live trapping. We found a strong negative synergistic effect of predators and coccidia on survival. Importantly, we found that predators increased both the prevalence and intensity of coccidian infection in voles through immune suppression induced by predation stress, while increased coccidian infection reduced plasma protein and hematocrit level of voles, which may impair anti-predator ability of voles and lead to an increase in predation. Our finding showed when voles are exposed to both predation risk and infection, their synergistic effects greatly reduce overwinter survival and population density. This may be an important mechanism influencing population dynamics in small mammals.

Are gastrointestinal parasites associated with the cyclic population dynamics of their arctic lemming hosts?

Many rodents, including most populations of arctic lemmings (genus Dicrostonyx and Lemmus), have cyclic population dynamics. Among the numerous hypotheses which have been proposed and tested to explain this typical characteristic of some terrestrial vertebrate communities, trophic interactions have often been presented as the most likely drivers of these periodic fluctuations. The possible role of parasites has, however, only seldom been assessed. In this study, we genetically measured the prevalence of two endoparasite taxa, eimerians and cestodes, in 372 faecal samples from collared lemmings, over a five year period and across three distant sites in Northeast Greenland. Prevalence of cestodes was low (2.7% over all sites and years) and this taxon was only found at one site (although in 4 out of 5 years) in adult hosts. By contrast, we found high prevalence for eimerians (77.7% over all sites and years), which occurred at all sites, in every year, for both age classes (at the Hochstetter Forland site where both adult and juvenile faeces were collected) and regardless of reproductive and social status inferred from the characteristics of the lemming nests where the samples had been collected. Prevalence of eimerians significantly varied among years (not among sites) and was higher for juvenile than for adult lemmings at the Hochstetter Forland site. However, higher prevalence of eimerians (P_t) was only associated with lower lemming density (N_t) at one of the three sites and we found no delayed density dependence between N_t and P_t+1 to support the parasite hypothesis. Our results show that there is no clear relation between lemming density and eimerian faecal prevalence in Northeast Greenland and hence no evidence that eimerians could be driving the cyclic population dynamics of collared lemmings in this region.

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Prevalence of eimerians and cestodes was measured in collared lemming in Greenland.

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Prevalence of cestodes was low (2.7%; one site only) compared to eimerians (78%).

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Prevalence of eimerians was higher for juveniles and varied among years.

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Prevalence of eimerians was negatively associated with lemming density at one site.

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lack of delayed density dependence does not support the parasite hypothesis for lemming cycles.

Heterochrony of puberty in the European badger (Meles meles) can be explained by growth rate and group-size: Evidence for two endocrinological phenotypes

Puberty is a key stage in mammalian ontogeny, involving endocrinological, physiological and behavioural changes, moderated by intrinsic and extrinsic factors. Thus, not all individuals within one population achieve sexual maturity simultaneously. Here, using the European badger (Meles meles) as a model, we describe male testosterone and female oestrone profiles (using Enzyme-immunoassays) from first capture (3 months, post-weaning) until 28 months (attaining sexual maturity and final body size), along with metrics of somatic growth, scent gland development and maturation of external reproductive organs as well as intra-specific competition. In both sexes, endocrinological puberty commenced at ca. 11 months. Thereafter, cub hormone levels followed adult seasonal hormone patterns but at lower levels, with the majority of cubs reaching sexual maturity during their second mating season (22-28 months). Interestingly, there was evidence for two endocrinological phenotypes among male cubs (less evident in females), with early developers reaching sexual maturity at 11 months (first mating season) and late developers reaching sexual maturity at 22-26 months (second mating season). Early developers also attained a greater proportion of their ultimate adult size by 11 months, exhibiting faster growth rates than late developers (despite having similar adult size). Male cubs born into larger social groups tended to follow the late developer phenotype. Our results support the hypothesis that a minimum body size is required to reach sexual maturity, which may be achieved at different ages, even within a single population, where early maturity can confer individual fitness advantages and enhance population growth rate.

Assessment of Trade-Offs between Simultaneous Immune Challenges in a Slow-Living Subterranean Rodent

The coexistence of two or more infectious agents in the same host is common in nature. Given this, the study of trade-offs within the immune system itself is key to understanding how immune defenses act in wild species in their natural environment. Here we assessed the possible trade-off between an inflammatory response (induced by phytohemagglutinin [PHA]; involving innate and adaptive responses in the study species) and an antibody response (induced by sheep red blood cells [SRBC]; adaptive response) in a slow-living subterranean rodent, the Talas tuco-tuco (Ctenomys talarum Thomas, 1898). According to life-history theory, slow-living species should rely more heavily on adaptive immunity, which develops more slowly than an innate response but is beneficial against repeated infections. Individual physiological condition (estimated by measuring levels of infection and immune, nutritional, and stress parameters) was analyzed during immune challenges. Contrary to what was expected, we found that the magnitude and energetic costs of both immune responses were similar when stimulated alone or simultaneously. Variation in natural antibodies, neutrophils, basophils, total leukocytes, and the ratio of neutrophils to lymphocytes in relation to the different treatments was also detected. In particular, natural antibodies were negatively affected by the induction of both immune challenges simultaneously and an increase of neutrophil counts was detected in all animals with the exception of those challenged with SRBC, while the pattern of variation of basophils, total leukocytes, and ratio of neutrophils to lymphocytes was not clearly associated with any triggered immune response. In general, our results suggest the absence of an energetic or resource-based trade-off between the immune responses triggered by PHA and SRBC in C. talarum.

Investigation into the genetic diversity in toll-like receptors 2 and 4 in the European badger Meles meles

The Toll-like receptor (TLR) genes are a conserved family of genes central to the innate immune response to pathogen infection. They encode receptor proteins, recognise pathogen associated molecular patterns (PAMPs) and trigger initial immune responses. In some host-pathogen systems, it is reported that genetic differences, such as single nucleotide polymorphisms (SNPs), associate with disease resistance or susceptibility. Little is known about TLR gene diversity in the European badger (Meles meles). We collected DNA from UK badgers, carried out PCR amplification of the badger TLR2 gene and exon 3 of TLR4 and determined DNA sequences for individual badgers for TLR2 (n = 61) and TLR4 exon 3 (n = 59). No polymorphism was observed in TLR4. Three TLR2 amino acid haplotype variants were found. Ninety five percent of badgers were homozygous for one common haplotype (H1), the remaining three badgers had genotypes H1/H3, H1/H2 and H2/H2. By broad comparison with other species, diversity in TLR genes in badgers seems low. This could be due to a relatively localised sampling or inherent low genetic diversity. Further studies are required to assess the generality of the low observed diversity and the relevance to the immunological status of badgers.

Causes of mortality and morbidity in free-ranging mustelids in Switzerland: necropsy data from over 50 years of general health surveillance

BACKGROUND

Although mustelids occur worldwide and include a wide range of species, little is known about the diseases affecting them. Mustelids have regularly been submitted for post mortem investigation in the framework of the program for general wildlife health surveillance in Switzerland, which has been in place for nearly 60 years. We performed a retrospective analysis of the necropsy reports on mustelids submitted to the diagnostic service of the University of Bern. The aims of this study were to present an overview of the causes of mortality and morbidity observed in these carnivores, to assess differences among species, to assess changes in disease detection over the study period, and to describe the pathology of selected diseases.

RESULTS

Five hundred and sixty-six reports from 1958 to 2015 were analyzed. Most animals were stone martens (Martes foina, 46%) and badgers (Meles meles, 44%); the remaining species were polecats (Mustela putorius, 4.7%), pine martens (Martes martes, 2%), stoats (Mustela erminea, 1.4%), weasels (Mustela nivalis, 0.8%) and otters (Lutra lutra, 0.3%). Infectious diseases (n = 262) were frequent and were mostly bacterial or viral; non-infectious conditions (n = 169) were less common and were mostly traumatic or due to metabolic disorders. The most frequent diagnoses included distemper (75% were badgers), amyloidosis (96% were martens), bacterial respiratory infections (all mustelids), biting lice (badgers only) and pulmonary and gastro-intestinal helminths (all species). Less frequent diseases included histoplasmosis (badgers only), aspergillosis, toxoplasmosis, hepatozoonosis, and sarcoptic mange. Lesions due to infection with distemper virus were primarily appreciated in the respiratory tract and central nervous system; they presented species-specific characteristics such as necrosis in the ependyma in badgers and absence of syncytia in stone martens. Amyloidosis in martens was multisystemic in most cases and included both AA and AL amyloidosis; the main macroscopic change was severe splenomegaly.

CONCLUSION

Infectious diseases were the most frequent causes of morbidity and mortality of mustelids, with marked species-specific differences. Lung and skin were the most commonly affected organs. Contagious diseases such as canine distemper, sarcoptic mange and rabies in mustelids showed a similar temporal pattern as in red foxes (Vulpes vulpes), suggesting pathogen spillovers from foxes to mustelids.

Androgens predict parasitism in female meerkats: a new perspective on a classic trade-off

The immunocompetence handicap hypothesis posits that androgens in males can be a 'double-edged sword', actively promoting reproductive success, while also negatively impacting health. Because there can be both substantial androgen concentrations in females and significant androgenic variation among them, particularly in species portraying female social dominance over males or intense female-female competition, androgens might also play a role in mediating female health and fitness. We examined this hypothesis in the meerkat (Suricata suricatta), a cooperatively breeding, social carnivoran characterized by aggressively mediated female social dominance and extreme rank-related reproductive skew. Dominant females also have greater androgen concentrations and harbour greater parasite loads than their subordinate counterparts, but the relationship between concurrent androgen concentrations and parasite burdens is unknown. We found that a female's faecal androgen concentrations reliably predicted her concurrent state of endoparasitism irrespective of her social status: parasite species richness and infection by Spirurida nematodes, Oxynema suricattae, Pseudandrya suricattae and coccidia were greater with greater androgen concentrations. Based on gastrointestinal parasite burdens, females appear to experience the same trade-off in the costs and benefits of raised androgens as do the males of many species. This trade-off presumably represents a health cost of sexual selection operating in females.

No Compensatory Relationship between the Innate and Adaptive Immune System in Wild-Living European Badgers

The innate immune system provides the primary vertebrate defence system against pathogen invasion, but it is energetically costly and can have immune pathological effects. A previous study in sticklebacks found that intermediate major histocompatibility complex (MHC) diversity correlated with a lower leukocyte coping capacity (LCC), compared to individuals with fewer, or many, MHC alleles. The organization of the MHC genes in mammals, however, differs to the highly duplicated MHC genes in sticklebacks by having far fewer loci. Using European badgers (Meles meles), we therefore investigated whether innate immune activity, estimated functionally as the ability of an individual’s leukocytes to produce a respiratory burst, was influenced by MHC diversity. We also investigated whether LCC was influenced by factors such as age-class, sex, body condition, season, year, neutrophil and lymphocyte counts, and intensity of infection with five different pathogens. We found that LCC was not associated with specific MHC haplotypes, MHC alleles, or MHC diversity, indicating that the innate immune system did not compensate for the adaptive immune system even when there were susceptible MHC alleles/haplotypes, or when the MHC diversity was low. We also identified a seasonal and annual variation of LCC. This temporal variation of innate immunity was potentially due to physiological trade-offs or temporal variation in pathogen infections. The innate immunity, estimated as LCC, does not compensate for MHC diversity suggests that the immune system may function differently between vertebrates with different MHC organizations, with implications for the evolution of immune systems in different taxa.

In situ adaptive response to climate and habitat quality variation: spatial and temporal variation in European badger (Meles meles) body weight

Variation in climatic and habitat conditions can affect populations through a variety of mechanisms, and these relationships can act at different temporal and spatial scales. Using post-mortem badger body weight records from 15 878 individuals captured across the Republic of Ireland (7224 setts across ca. 15 000 km(2) ; 2009-2012), we employed a hierarchical multilevel mixed model to evaluate the effects of climate (rainfall and temperature) and habitat quality (landscape suitability), while controlling for local abundance (unique badgers caught/sett/year). Body weight was affected strongly by temperature across a number of temporal scales (preceding month or season), with badgers being heavier if preceding temperatures (particularly during winter/spring) were warmer than the long-term seasonal mean. There was less support for rainfall across different temporal scales, although badgers did exhibit heavier weights when greater rainfall occurred one or 2 months prior to capture. Badgers were also heavier in areas with higher landscape habitat quality, modulated by the number of individuals captured per sett, consistent with density-dependent effects reducing weights. Overall, the mean badger body weight of culled individuals rose during the study period (2009-2012), more so for males than for females. With predicted increases in temperature, and rainfall, augmented by ongoing agricultural land conversion in this region, we project heavier individual badger body weights in the future. Increased body weight has been associated with higher fecundity, recruitment and survival rates in badgers, due to improved food availability and energetic budgets. We thus predict that climate change could increase the badger population across the Republic of Ireland. Nevertheless, we emphasize that, locally, populations could still be vulnerable to extreme weather variability coupled with detrimental agricultural practice, including population management.

Heterozygosity-fitness correlations in a wild mammal population: accounting for parental and environmental effects

HFCs (heterozygosity–fitness correlations) measure the direct relationship between an individual's genetic diversity and fitness. The effects of parental heterozygosity and the environment on HFCs are currently under-researched. We investigated these in a high-density U.K. population of European badgers (Meles meles), using a multimodel capture–mark–recapture framework and 35 microsatellite loci. We detected interannual variation in first-year, but not adult, survival probability. Adult females had higher annual survival probabilities than adult males. Cubs with more heterozygous fathers had higher first-year survival, but only in wetter summers; there was no relationship with individual or maternal heterozygosity. Moist soil conditions enhance badger food supply (earthworms), improving survival. In dryer years, higher indiscriminate mortality rates appear to mask differential heterozygosity-related survival effects. This paternal interaction was significant in the most supported model; however, the model-averaged estimate had a relative importance of 0.50 and overlapped zero slightly. First-year survival probabilities were not correlated with the inbreeding coefficient (f); however, small sample sizes limited the power to detect inbreeding depression. Correlations between individual heterozygosity and inbreeding were weak, in line with published meta-analyses showing that HFCs tend to be weak. We found support for general rather than local heterozygosity effects on first-year survival probability, and g2 indicated that our markers had power to detect inbreeding. We emphasize the importance of assessing how environmental stressors can influence the magnitude and direction of HFCs and of considering how parental genetic diversity can affect fitness-related traits, which could play an important role in the evolution of mate choice.

A multi-metric approach to investigate the effects of weather conditions on the demographic of a terrestrial mammal, the european badger (Meles meles)

Models capturing the full effects of weather conditions on animal populations are scarce. Here we decompose yearly temperature and rainfall into mean trends, yearly amplitude of change and residual variation, using daily records. We establish from multi-model inference procedures, based on 1125 life histories (from 1987 to 2008), that European badger (Meles meles) annual mortality and recruitment rates respond to changes in mean trends and to variability in proximate weather components. Variation in mean rainfall was by far the most influential predictor in our analysis. Juvenile survival and recruitment rates were highest at intermediate levels of mean rainfall, whereas low adult survival rates were associated with only the driest, and not the wettest, years. Both juvenile and adult survival rates also exhibited a range of tolerance for residual standard deviation around daily predicted temperature values, beyond which survival rates declined. Life-history parameters, annual routines and adaptive behavioural responses, which define the badgers’ climatic niche, thus appear to be predicated upon a bounded range of climatic conditions, which support optimal survival and recruitment dynamics. That variability in weather conditions is influential, in combination with mean climatic trends, on the vital rates of a generalist, wide ranging and K-selected medium-sized carnivore, has major implications for evolutionary ecology and conservation.

Evolution of MHC class I genes in the European badger (Meles meles)

The major histocompatibility complex (MHC) plays a central role in the adaptive immune system and provides a good model with which to understand the evolutionary processes underlying functional genes. Trans-species polymorphism and orthology are both commonly found in MHC genes; however, mammalian MHC class I genes tend to cluster by species. Concerted evolution has the potential to homogenize different loci, whereas birth-and-death evolution can lead to the loss of orthologs; both processes result in monophyletic groups within species. Studies investigating the evolution of MHC class I genes have been biased toward a few particular taxa and model species. We present the first study of MHC class I genes in a species from the superfamily Musteloidea. The European badger (Meles meles) exhibits moderate variation in MHC class I sequences when compared to other carnivores. We identified seven putatively functional sequences and nine pseudogenes from genomic (gDNA) and complementary (cDNA) DNA, signifying at least two functional class I loci. We found evidence for separate evolutionary histories of the α1 and α2/α3 domains. In the α1 domain, several sequences from different species were more closely related to each other than to sequences from the same species, resembling orthology or trans-species polymorphism. Balancing selection and probable recombination maintain genetic diversity in the α1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the α2/α3 domains have most likely undergone concerted evolution, where recombination has homogenized the α2/α3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.

Year-long presence of Eimeria echidnae and absence of Eimeria tachyglossi in captive short-beaked echidnas ( Tachyglossus aculeatus )

The short-beaked echidna ( Tachyglossus aculeatus ) is 1 of 5 extant species of monotreme, found only in Australia and Papua New Guinea. The aim of this study was to identify the species of coccidia present and establish a range of subclinical Eimeria spp. (Coccidia: Apicomplexa) oocyst shedding in echidnas from eastern Australia over 18 mo. The coccidia were detected in 89% (49/55) of fecal samples from 12 long-term monitored and healthy captive echidnas, 75% (3/4) of 4 healthy long-term captive echidnas, 83% (5/6) of 6 short-term captive echidnas, and 60% (6/10) of 10 wild echidnas. Echidnas captive for 4 to 23 yr shed 100-46,000 oocysts g(-1) of E. echidnae and remained clinically healthy during this study. Sub-adult and adult wild, and short-term captive, echidnas shed oocysts of both E. echidnae and E. tachyglossi . The lack of coccidia in juvenile short-beaked echidnas suggests these animals are probably non-immune and should not be placed in environments heavily contaminated with oocysts. In addition, no oocysts were found in captive long-beaked echidnas ( Zaglossus bartoni bartoni , n  =  2) housed at Taronga Zoo. This study represents an important step in understanding the host-parasite interaction between coccidia and short-beaked echidnas.

Evidence for a role of the host-specific flea (Paraceras melis) in the transmission of Trypanosoma (Megatrypanum) pestanai to the European badger

We investigated the epidemiology of Trypanosoma pestanai infection in European badgers (Meles meles) from Wytham Woods (Oxfordshire, UK) to determine prevalence rates and to identify the arthropod vector responsible for transmission. A total of 245 badger blood samples was collected during September and November 2009 and examined by PCR using primers derived from the 18S rRNA of T. pestanai. The parasite was detected in blood from 31% of individuals tested. T. pestanai was isolated from primary cultures of Wytham badger peripheral blood mononuclear cells and propagated continually in vitro. This population was compared with cultures of two geographically distinct isolates of the parasite by amplified fragment length polymorphism (AFLP) and PCR analysis of 18S rDNA and ITS1 sequences. High levels of genotypic polymorphism were observed between the isolates. PCR analysis of badger fleas (Paraceras melis) collected from infected individuals at Wytham indicated the presence of T. pestanai and this was confirmed by examination of dissected specimens. Wet smears and Giemsa-stained preparations from dissected fleas revealed large numbers of trypanosome-like forms in the hindgut, some of which were undergoing binary fission. We conclude that P. melis is the primary vector of T. pestanai in European badgers.

Variations in Badger (Meles meles) Sett Microclimate: Differential Cub Survival between Main and Subsidiary Setts, with Implications for Artificial Sett Construction

Maintaining homeothermy is essential for mammals, but has considerable energetic costs. In this study, we monitored the internal conditions of setts within five European badger (Meles meles) social groups during the cub-rearing season, that is, February to July, in 2004. Sett temperature showed substantial and significant variation over this period, while relative humidity remained stable throughout. Microclimate was least stable during the period for which cubs remain entirely below ground between February and April; however here the instrumented main sett demonstrated a much warmer and more stable temperature regime than did nearby subsidiary outliers. We thus postulate that the energy budget of reproducing females could be affected by even small temperature fluctuations, militating for optimal sett choice. For comparison we also report microclimatic data from two artificial setts and found them to be markedly inferior in terms of thermal insulative properties, suggesting that man-made setts may need more careful consideration in both thermal and spatial setts network in each territory to adequately compensate the loss (e.g., destruction due to development) of a natural sett, especially as a breeding den.

Environmental variation at the onset of independent foraging affects full-grown body mass in the red fox

The period following the withdrawal of parental care has been highlighted as a key developmental period for juveniles. One reason for this is that juveniles cannot forage as competently as adults, potentially placing them at greater risk from environmentally-induced changes in food availability. However, no study has examined this topic. Using a long-term dataset on red foxes (Vulpes vulpes), we examined (i) dietary changes that occurred in the one-month period following the attainment of nutritional independence, (ii) diet composition in relation to climatic variation, and (iii) the effect of climatic variation on subsequent full-grown mass. Diet at nutritional independence contained increased quantities of easy-to-catch food items (earthworms and insects) when compared with pre-independence. Interannual variation in the volume of rainfall at nutritional independence was positively correlated to the proportion of earthworms in cub diet. Pre-independence cub mass and rainfall immediately following nutritional independence explained a significant proportion of variance in full-grown mass, with environmental variation affecting full-grown mass of the entire cohorts. Thus, weather-mediated availability of easy-to-catch food items at a key developmental stage has lifelong implications for the development of juvenile foxes by affecting full-grown mass, which in turn appears to be an important component of individual reproductive potential.

Epidemiology of parasitic protozoan infections in Soay sheep (Ovis aries L.) on St Kilda

The feral Soay sheep (Ovis aries L.) population on Hirta, St Kilda, is host to a diverse component parasite community, but previous parasitological studies of the population have only focussed on the metazoan species. This paper reports the first epidemiological study of the protozoan species comprising Cryptosporidium parvum, Giardia duodenalis and 11 species of Eimeria in Soay sheep across 3 years of varying host population density. Prevalence and intensity of almost all species of protozoa significantly decreased with host age, with the exception of E. granulosa, which increased in prevalence with host age. The prevalence of C. parvum appeared to vary positively with host population density but that of G. duodenalis did not vary significantly with density. Most species of Eimeria showed a distinct lag in infection level following the host population crash of 2002, taking up to 2 years to decrease. Mixed Eimeria species intensity and diversity were highest in 2002, a year of low host density. Parasite diversity decreased with host age and was higher in males. There were 5 positive pair-wise associations between protozoa species in terms of prevalence. The results of this study highlight the potential for protozoal infection to shape the evolution of parasite resistance in wild host populations harbouring diverse parasite species.

Eimeria-parasites are associated with a lowered mother's and offspring's body condition in island and mainland populations of the bank vole

This study, based on correlative data, tests the hypothesis that infections withEimeriaspp. parasites exert a significant loss of fitness of bank voles (Clethrionomys glareolus) reflected in lower reproductive success and survival, declining host population densities and are associated positively with population size. The study was conducted in 20 mainland and 27 island populations in central Finland during May–September in 1999. Faecal samples showed that 28% of 767 individuals were infected withEimeriaspp. The presence ofEimeriaparasites was higher in dense mainland populations than in sparsely populated islands. Eimerian infections increased during the course of the breeding season, probably as a result of the high infection rate of young individuals. Accordingly, the body masses of bank voles were negatively related to the presence ofEimeriaspp. Reproductive output, as measured by the breeding probability of females and litter size, was not associated with the presence of eimerian infection. Interestingly, the body condition of the infected mothers appeared to be low. Moreover, mother's body condition was the single most important variable studied that showed a positive correlation to pup's body condition at birth. On small islands ([les ]3·2 ha) that were comprehensively trapped, the mean number ofEimeriaspp. in the bank vole population was negatively related to density changes of the bank vole population during the study. Our data are consistent with the idea that infection with coccidian parasites may be one of the factors responsible for declining host populations in small, isolated populations.

Female Receptiveity, Embryonic Diapause, and Superfetation in the European Badger (Meles Meles: Implications for the Reproductive Tactics of Males and Females

The European badger Meles meles is thought to mate throughout the year with two mating peaks occurring in late winter/spring and summer/autumn. After mating, fertilized ova enter embryonic diapause (delayed implantation) at the blastocyst stage, which lasts up to eleven months. Even if mating is successful, however, the estrous cycle may continue during embryonic diapause, which suggests that female badgers are capable of superfetation (conception during pregnancy). This may increase female fitness by facilitating polyandry, and reduce the risk of infanticide by resident males through paternity confusion. Detailed understanding of female receptivity, specifically the association of superfetation with embryonic diapause, may explain field observations of seemingly inconsistent reproductive tactics of male badgers with regard to, for instance, whether or not they guard mates or defend territories. The combination of embryonic diapause and superfetation may occur in other mustelids; if so, the sociobiology of mustelids will need reevaluating, and the Mustelidae may prove to be a good model taxon for studies of sexual conflict in the reproduction of eutherian mammals.

Use of an electronic nose to diagnose Mycobacterium bovis infection in badgers and cattle

It is estimated that more than 50 million cattle are infected with Mycobacterium bovis worldwide, resulting in severe economic losses. Current diagnosis of tuberculosis (TB) in cattle relies on tuberculin skin testing, and when combined with the slaughter of test-positive animals, it has significantly reduced the incidence of bovine TB. The failure to eradicate bovine TB in Great Britain has been attributed in part to a reservoir of the infection in badgers (Meles meles). Accurate and reliable diagnosis of infection is the cornerstone of TB control. Bacteriological diagnosis has these characteristics, but only with samples collected postmortem. Unlike significant wild animal reservoirs of M. bovis that are considered pests in other countries, such as the brushtail possum (Trichosurus vulpecula) in New Zealand, the badger and its sett are protected under United Kingdom legislation (The Protection of Badgers Act 1992). Therefore, an accurate in vitro test for badgers is needed urgently to determine the extent of the reservoir of infection cheaply and without destroying badgers. For cattle, a rapid on-farm test to complement the existing tests (the skin test and gamma interferon assay) would be highly desirable. To this end, we have investigated the potential of an electronic nose (EN) to diagnose infection of cattle or badgers with M. bovis, using a serum sample. Samples were obtained from both experimentally infected badgers and cattle, as well as naturally infected badgers. Without exception, the EN was able to discriminate infected animals from controls as early as 3 weeks after infection with M. bovis, the earliest time point examined postchallenge. The EN approach described here is a straightforward alternative to conventional methods of TB diagnosis, and it offers considerable potential as a sensitive, rapid, and cost-effective means of diagnosing M. bovis infection in cattle and badgers.