42 resultados para Vampire bats

em Université de Lausanne, Switzerland


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Most countries in Western Europe are currently free of rabies in terrestrial mammals. Nevertheless, rabies remains a residual risk to public health due to the natural circulation of bat-specific viruses, such as European bat lyssaviruses (EBLVs). European bat lyssavirus types 1 and 2 (EBLV-1 and EBLV-2) are widely distributed throughout Europe, but little is known of their true prevalence and epidemiology. We report that only three out of 837 brains taken from bats submitted to the Swiss Rabies Centre between 1976 and 2009 were found by immunofluorescence (FAT) to be positive for EBLVs. All three positive cases were in Myotis daubentoni, from 1992, 1993 and 2002. In addition to this passive surveillance, we undertook a targeted survey in 2009, aimed at detecting lyssaviruses in live bats in Switzerland. A total of 237 bats of the species M. daubentoni, Myotis myotis, Eptesicus serotinus and Nyctalus noctula were captured at different sites in western Switzerland. Oropharyngeal swabs and blood from each individual were analysed by RT-PCR and rapid fluorescent focus inhibition test (RFFIT), respectively. RNA corresponding to EBLV-2 was detected from oropharyngeal swabs of a single M. daubentoni bat, but no infectious virus was found. Molecular phylogenetic analysis revealed that the corresponding sequence was closely related to the other EBLV-2 sequences identified in previous rabies isolates from Swiss bats (particularly to that found at Geneva in 2002). Three M. daubentoni bats were found to be seropositive by RFFIT. In conclusion, even though the prevalence is low in Switzerland, continuous management and surveillance are required to assess the potential risk to public health.

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1. Landscape modification is often considered the principal cause of population decline in many bat species. Thus, schemes for bat conservation rely heavily on knowledge about species-landscape relationships. So far, however, few studies have quantified the possible influence of landscape structure on large-scale spatial patterns in bat communities. 2. This study presents quantitative models that use landscape structure to predict (i) spatial patterns in overall community composition and (ii) individual species' distributions through canonical correspondence analysis and generalized linear models, respectively. A geographical information system (GIS) was then used to draw up maps of (i) overall community patterns and (ii) distribution of potential species' habitats. These models relied on field data from the Swiss Jura mountains. 3. Fight descriptors of landscape structure accounted for 30% of the variation in bat community composition. For some species, more than 60% of the variance in distribution could be explained by landscape structure. Elevation, forest or woodland cover, lakes and suburbs, were the most frequent predictors. 4. This study shows that community composition in bats is related to landscape structure through species-specific relationships to resources. Due to their nocturnal activities and the difficulties of remote identification, a comprehensive bat census is rarely possible, and we suggest that predictive modelling of the type described here provides an indispensable conservation tool.

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Which of these two confounding factors, weather or food availability - that largely correlate and interact - controls the timing of parturition in insectivorous bats? To answer this question. we took advantage of a predator-prey system that offers a unique opportunity to perform natural experiments. The phenology of reproduction of two sibling bat species that inhabit the same colonial roosts, but exploit different feeding niches. was investigated. Myotis myotis feeds mainly on carabid beetles, a food source available from the end of hibernation onwards, whereas bush crickets, the main prey of M. blythii, are not available early in the season due to their successive instars; cockchafers are actually the sole possible alternative prey for M. blythii at that time of the year, but they occur every third year only, independently of local weather conditions. By comparing the species responses to the presence/absence of cockchafers, we could test the hypothesis that food availability, rather than climate. influences the timing of bat parturition. Our data show that Nt. blythii gave birth, on average. 10 d later than M. myotis in years without cockchafers, whilst parturition (1) was synchronous during cockchafer years, and (2) did not show much among-year time variation in M. myotis. This suggests that food availability is the chief factor regulating the timing of parturition in mouse-eared bats.

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Time-expanded echolocation calls were recorded from 29 species of Neotropical bats in lowland moist tropical forest in Trinidad, West Indies with three aims (I) to describe the echolocation calls of the members of a diverse Neotropical bat community, especially members of the family Phyllostomidae, whose calls are not well documented (2) to investigate whether multivariate analysis of calls allows species and foraging guilds to be identified and (3) to evaluate the use of bat detectors in surveying the phyllostomids of Neotropical forests. The calls of 12 species of the family Phyllostomidae are described here for the first time and a total of 29 species, belonging to five families (Emballonuridae, Mormoopidae, Phyllostomidae, Molossidae and Vespertilionidae) were recorded Quadratic discriminant function analysis (DFA) was used to obtain classification rates for each one of 11 individual species and for six guilds (based on diet, foraging mode and habitat) comprising 26 species Overall classification rates were low compared to similar studies conducted in the Palaeotropics We suggest that this may be due to a combination of ecological plasticity for certain species and a loose relationship between echolocation call shape, fine-grained resource partitioning and resource acquisition in phyllostomids

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Protected areas are valuable in conserving tropical biodiversity, but an insufficient understanding of species diversity and distributions makes it difficult to evaluate their effectiveness. This is especially true on Borneo, a species rich island shared by three countries, and is particularly concerning for bats, a poorly known component of mammal diversity that may be highly susceptible to landscape changes. We reviewed the diversity, distributions and conservation status of 54 bat species to determine the representation of these taxa in Borneo's protected areas, and whether these reserves complement each other in terms of bat diversity. Lower and upper bound estimates of bat species composition were characterised in 23 protected areas and the proposed boundaries of the Heart of Borneo conservation area. We used lower and upper bound estimates of species composition. By using actual inventories, species representation was highly irregular, and even if some reserves were included in the Heart of Borneo, the protected area network would still exhibit low complementarity. By inferring species presence from distributions, composition between most reserves was similar, and complementarity was much higher. Predicting species richness using abundance information suggested that bat species representation in reserves may lie between these two extremes. We recommend that researchers better sample biodiversity over the island and address the conservation threats faced in Borneo both within and outside protected areas. While the Heart of Borneo Initiative is commendable, it should not divert attention from other conservation areas.

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Investigating macro-geographical genetic structures of animal populations is crucial to reconstruct population histories and to identify significant units for conservation. This approach may also provide information about the intraspecific flexibility of social systems. We investigated the history and current structure of a large number of populations in the communally breeding Bechstein's bat (Myotis bechsteinii). Our aim was to understand which factors shape the species' social system over a large ecological and geographical range. Using sequence data from one coding and one noncoding mitochondrial DNA region, we identified the Balkan Peninsula as the main and probably only glacial refugium of the species in Europe. Sequence data also suggest the presence of a cryptic taxon in the Caucasus and Anatolia. In a second step, we used seven autosomal and two mitochondrial microsatellite loci to compare population structures inside and outside of the Balkan glacial refugium. Central European and Balkan populations both were more strongly differentiated for mitochondrial DNA than for nuclear DNA, had higher genetic diversities and lower levels of relatedness at swarming (mating) sites than in maternity (breeding) colonies, and showed more differentiation between colonies than between swarming sites. All these suggest that populations are shaped by strong female philopatry, male dispersal, and outbreeding throughout their European range. We conclude that Bechstein's bats have a stable social system that is independent from the postglacial history and location of the populations. Our findings have implications for the understanding of the benefits of sociality in female Bechstein's bats and for the conservation of this endangered species.

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For a better understanding of the complex coevolutionary processes between hosts and parasites, accurate identification of the actors involved in the interaction is of fundamental importance. Blood parasites of the Order Haemosporidia, responsible for malaria, have become the focus of a broad range of studies in evolutionary biology. Interestingly, molecular-based studies on avian malaria have revealed much higher species diversity than previously inferred with morphology. Meanwhile, studies on bat haemosporidian have been largely neglected. In Europe, only one genus (Polychromophilus) and two species have been morphologically described. To evaluate the presence of potential cryptic species and parasite prevalence, we undertook a molecular characterization of Polychromophilus in temperate zone bats. We used a nested-PCR approach on the cytochrome b mitochondrial gene to detect the presence of parasites in 237 bats belonging to four different species and in the dipteran bat fly Nycteribia kolenatii, previously described as being the vector of Polychromophilus. Polychromophilus murinus was found in the four bat species and in the insect vector with prevalence ranging from 4% for Myotis myotis to 51% for M. daubentoni. By sequencing 682 bp, we then investigated the phylogenetic relationships of Polychromophilus to other published malarial lineages. Seven haplotypes were found, all very closely related, suggesting the presence of a single species in our samples. These haplotypes formed a well-defined clade together with Haemosporidia of tropical bats, revealing a worldwide distribution of this parasite mostly neglected by malarial studies since the 1980s.

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Capsule We report a review of the occurrence of bats in the Barn Owl diet Tyto alba in Europe. Based on 802 studies reporting 4.02 million prey items identified in pellets, 4949 were bats (0.12%). We found that bat predation decreased during the last 150 years, is more frequent on islands than mainland, and is higher in eastern than western Europe and in southern than northern Europe. Although Barn Owls usually capture bats opportunistically, they can sometimes specialize on them.

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Cospeciation between host-parasite species is generally thought to result in mirror-image congruent phylogenies. Incongruence can be explained by mechanisms such as host switching, duplication, failure to speciate and sorting events. To investigate the level of association in the host-parasite relationship between Spinturnicid mites and their bat hosts, we constructed the phylogenetic tree of the genus Spinturnix (Acari, Mesostigmata) and compared it to the host phylogeny. We sequenced 938bp of the mitochondrial 16S rDNA and Cytochrome Oxydase subunit I (COI) genes among eleven morphospecies of Spinturnix collected on 20 European Vespertilionid and Rhinolophid bat species. Phylogenetic reconstruction of hosts and parasites showed statistical evidence for cospeciation and suggested that their evolutionary history involved also failure to speciate events and host switches. The latter seem to be mainly promoted by similar roosting habits of the host. As currently understood, host associations of Spinturnicid mites likely results from a complex interaction between the phylogenetic history of the host and the behaviour and the ecology of both parasite and host.

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The bat fauna of Mozambique is poorly documented. We conducted a series of inventories across the country between 2005 and 2009, resulting in the identification of 50 species from 41 sites. Of these, seven species represent new national records that increase the country total to 67 species. These data include results from the first detailed surveys across northern Mozambique, over an area representing almost 50% of the country. We detail information on new distribution records and measurements of these specimens. Special attention is paid to the Rhinolophidae, because these include several taxa that are currently in a state of taxonomic confusion. Furthermore, we also present some notes on taxonomy, ecology and echolocation calls. Finally, we combine modelled distributions to present predicted species richness across the country. Species richness was lowest across the coastal plain, to the east and far north, and is predicted to increase in association with rising altitude and higher topographic unevenness of the landscape.

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Parasite population structure is often thought to be largely shaped by that of its host. In the case of a parasite with a complex life cycle, two host species, each with their own patterns of demography and migration, spread the parasite. However, the population structure of the parasite is predicted to resemble only that of the most vagile host species. In this study, we tested this prediction in the context of a vector-transmitted parasite. We sampled the haemosporidian parasite Polychromophilus melanipherus across its European range, together with its bat fly vector Nycteribia schmidlii and its host, the bent-winged bat Miniopterus schreibersii. Based on microsatellite analyses, the wingless vector, and not the bat host, was identified as the least structured population and should therefore be considered the most vagile host. Genetic distance matrices were compared for all three species based on a mitochondrial DNA fragment. Both host and vector populations followed an isolation-by-distance pattern across the Mediterranean, but not the parasite. Mantel tests found no correlation between the parasite and either the host or vector populations. We therefore found no support for our hypothesis; the parasite population structure matched neither vector nor host. Instead, we propose a model where the parasite's gene flow is represented by the added effects of host and vector dispersal patterns.

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BackgroundThe great diversity of bat haemosporidians is being uncovered with the help of molecular tools. Yet most of these studies provide only snapshots in time of the parasites discovered. Polychromophilus murinus, a malaria-like blood parasite, specialised on temperate-zone bats is a species that is being `rediscovered¿. This study describes the infection dynamics over time and between host sex and age classes.MethodsFor three years we followed the members of three breeding colonies of Myotis daubentonii in Western Switzerland and screened them for the prevalence and parasitemia of P. murinus using both molecular tools and traditional microscopy. In order to identify more susceptible classes of hosts, we measured, sexed and aged all individuals. During one year, we additionally measured body temperature and haematocrit values.ResultsJuvenile bats demonstrated much higher parasitemia than any other age class sampled, suggesting that first exposure to the parasite is very early in life during which infections are also at their most intense. Moreover, in subadults there was a clear negative correlation between body condition and intensity of infection, whereas a weak positive correlation was observed in adults. Neither body temperature, nor haematocrit, two proxies used for pathology, could be linked to intensities of infection.ConclusionIf both weaker condition and younger age are associated with higher infection intensity, then the highest selection pressure exerted by P. murinus should be at the juvenile stage. Confusion over the identities and nomenclature of malarial-like parasites requires that molecular barcodes are coupled to accurate morphological descriptions.

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We assessed the effect of abandonment of sylvo-pastoral practices in chestnut orchards (Castanea sativa) on bats in southern Switzerland to determine practical recommendations for bat conservation. We compared bat species richness and foraging activities between traditionally managed and unmanaged chestnut orchards, testing the hypothesis that managed orchards provide better foraging opportunities and harbour more bat species. Echolocation calls of foraging bats were sampled simultaneously at paired sites of managed and unmanaged orchards using custom made recorders. Vegetation structure and aerial insect availability were sampled at the recording sites and used as explanatory variables in the model. In a paired sampling design, we found twice the number of bat species (12) and five times higher total foraging activity in the managed chestnut orchards compared to the unmanaged ones. Bat species with low flight manoeuvrability were 14 times more common in managed orchards, whereas bats with medium to high manoeuvrability were only 5 times more common than in abandoned orchards. The vegetation structure was less dense in managed orchards. However, management did not affect relative insect abundance. Bats primarily visited the most open orchards, free of undergrowth. As a result of restricted access into the overgrown forests, the abandonment of chestnut orchards leads to a decline in bat species richness and foraging activities. Continued management of chestnut orchards to maintain an open structure is important for the conservation of endangered bat species in the southern Swiss Alps.