Project description:The European badger (Meles meles) is of considerable interest in the UK as it is both a protected species and the main wildlife reservoir for bovine tuberculosis infection in cattle. While there have been three national badger surveys in the 1980s, 1990s and 2011-13, using the number of badger main setts as a proxy for the abundance of badger social groups, none has combined contemporary data on social group size at landscape and national scales. We estimated social group size by genotyping hair samples collected at 120 main setts across England and Wales and employing a capture-mark-recapture method based on genotypes. The estimated mean social group size in England and Wales was 6.74 (±0.63) badgers. There was considerable variation in badger social group size among Land Class Groups (LCGs), with a low of 2.67 in LCG3 and a high of 7.92 in LCG4. Combining these results with the recent Badger Sett Survey of England and Wales, we estimate there are approximately 485,000 badgers (95% confidence intervals 391,000-581,000) in England and Wales. Although direct comparison with previous estimates is not ideal owing to methodological differences, our results are consistent with a marked increase in the badger population of England and Wales since the 1980s.
Project description:Bovine tuberculosis (bTB), caused by Mycobacterium bovis, continues to be a serious economic problem for the British cattle industry. The Eurasian badger (Meles meles) is partly responsible for maintenance of the disease and its transmission to cattle. Previous attempts to manage the disease by culling badgers have been hampered by social perturbation, which in some situations is associated with increases in the cattle herd incidence of bTB. Following the licensing of an injectable vaccine, we consider the relative merits of management strategies to reduce bTB in badgers, and thereby reduce cattle herd incidence. We used an established simulation model of the badger-cattle-TB system and investigated four proposed strategies: business as usual with no badger management, large-scale proactive badger culling, badger vaccination, and culling with a ring of vaccination around it. For ease of comparison with empirical data, model treatments were applied over 150 km(2) and were evaluated over the whole of a 300 km(2) area, comprising the core treatment area and a ring of approximately 2 km. The effects of treatment were evaluated over a 10-year period comprising treatment for five years and the subsequent five year period without treatment. Against a background of existing disease control measures, where 144 cattle herd incidents might be expected over 10 years, badger culling prevented 26 cattle herd incidents while vaccination prevented 16. Culling in the core 150 km(2) plus vaccination in a ring around it prevented about 40 cattle herd breakdowns by partly mitigating the negative effects of culling, although this approach clearly required greater effort. While model outcomes were robust to uncertainty in parameter estimates, the outcomes of culling were sensitive to low rates of land access for culling, low culling efficacy, and the early cessation of a culling strategy, all of which were likely to lead to an overall increase in cattle disease.
Project description: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 ?1 and ?2/?3 domains. In the ?1 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 ?1 domain, evidenced by the detection of positive selection and a recombination event. By comparison, two recombination breakpoints indicate that the ?2/?3 domains have most likely undergone concerted evolution, where recombination has homogenized the ?2/?3 domains between genes, leading to species-specific clusters of sequences. Our findings highlight the importance of analyzing MHC domains separately.
Project description:Estimates of population size and trappability inform vaccine efficacy modelling and are required for adaptive management during prolonged wildlife vaccination campaigns. We present an analysis of mark-recapture data from a badger vaccine (Bacille Calmette-Guérin) study in Ireland. This study is the largest scale (755 km(2)) mark-recapture study ever undertaken with this species. The study area was divided into three approximately equal-sized zones, each with similar survey and capture effort. A mean badger population size of 671 (SD: 76) was estimated using a closed-subpopulation model (CSpM) based on data from capturing sessions of the entire area and was consistent with a separate multiplicative model. Minimum number alive estimates calculated from the same data were on average 49-51% smaller than the CSpM estimates, but these are considered severely negatively biased when trappability is low. Population densities derived from the CSpM estimates were 0.82-1.06 badgers km(-2), and broadly consistent with previous reports for an adjacent area. Mean trappability was estimated to be 34-35% per session across the population. By the fifth capture session, 79% of the adult badgers caught had been marked previously. Multivariable modelling suggested significant differences in badger trappability depending on zone, season and age-class. There were more putatively trap-wary badgers identified in the population than trap-happy badgers, but wariness was not related to individual's sex, zone or season of capture. Live-trapping efficacy can vary significantly amongst sites, seasons, age, or personality, hence monitoring of trappability is recommended as part of an adaptive management regime during large-scale wildlife vaccination programs to counter biases and to improve efficiencies.