Project description:Distress calls are a vocalization type widespread across the animal kingdom, emitted when the animals are under duress, e.g. when captured by a predator. Here, we report on an observation we came across serendipitously while recording distress calls from the bat species Carollia perspicillata, i.e. the existence of sex difference in the distress calling behaviour of this species. We show that in C. perspicillata bats, males are more likely to produce distress vocalizations than females when hand-held. Male bats call more, their calls are louder, harsher (faster amplitude modulated) and cover lower carrier frequencies than female vocalizations. We discuss our results within a framework of potential hormonal, neurobiological and behavioural differences that could explain our findings, and open multiple paths to continue the study of sex-related differences in vocal behaviour in bats.
Project description:Most mammals rely on the extraction of acoustic information from the environment in order to survive. However, the mechanisms that support sound representation in auditory neural networks involving sensory and association brain areas remain underexplored. In this study, we address the functional connectivity between an auditory region in frontal cortex (the frontal auditory field, FAF) and the auditory cortex (AC) in the bat Carollia perspicillata. The AC is a classic sensory area central for the processing of acoustic information. On the other hand, the FAF belongs to the frontal lobe, a brain region involved in the integration of sensory inputs, modulation of cognitive states, and in the coordination of behavioral outputs. The FAF-AC network was examined in terms of oscillatory coherence (local-field potentials, LFPs), and within an information theoretical framework linking FAF and AC spiking activity. We show that in the absence of acoustic stimulation, simultaneously recorded LFPs from FAF and AC are coherent in low frequencies (1-12 Hz). This "default" coupling was strongest in deep AC layers and was unaltered by acoustic stimulation. However, presenting auditory stimuli did trigger the emergence of coherent auditory-evoked gamma-band activity (>25 Hz) between the FAF and AC. In terms of spiking, our results suggest that FAF and AC engage in distinct coding strategies for representing artificial and natural sounds. Taken together, our findings shed light onto the neuronal coding strategies and functional coupling mechanisms that enable sound representation at the network level in the mammalian brain.
Project description:In 2012 and 2013, the genomic sequences of two novel influenza A virus (IAV) subtypes, designated H17N10 and H18N11, were identified via next-generation sequencing in the feces of the little yellow-shouldered fruit bat (Sturnira lilium) and the flat-faced fruit-eating bat (Artibeus planirostris), respectively. The pathogenesis caused by these viruses in their respective host species is currently insufficiently understood, which is primarily due to the inability to obtain and keep these bat species under appropriate environmental and biosafety conditions. Seba's short-tailed bats (Carollia perspicillata), in contrast, are close relatives and a natural H18N11 reservoir species, with the advantage of established animal husbandry conditions in academic research. To study viral pathogenesis in more detail, we here oro-nasally inoculated Seba's short-tailed bats with the bat IAV H18N11 subtype. Following inoculation, bats appeared clinically healthy, but the histologic examination of tissues revealed a mild necrotizing rhinitis. Consistently, IAV-matrix protein and H18-RNA positive cells were seen in lesioned respiratory and olfactory nasal epithelia, as well as in intestinal tissues. A RT-qPCR analysis confirmed viral replication in the conchae and intestines as well as the presence of viral RNA in the excreted feces, without horizontal transmission to naïve contact animals. Moreover, all inoculated animals seroconverted with low titers of neutralizing antibodies.
Project description:Aerodynamic theory has long been used to predict the power required for animal flight, but widely used models contain many simplifications. It has been difficult to ascertain how closely biological reality matches model predictions, largely because of the technical challenges of accurately measuring the power expended when an animal flies. We designed a study to measure flight speed-dependent aerodynamic power directly from the kinetic energy contained in the wake of bats flying in a wind tunnel. We compared these measurements with two theoretical predictions that have been used for several decades in diverse fields of vertebrate biology and to metabolic measurements from a previous study using the same individuals. A high-accuracy displaced laser sheet stereo particle image velocimetry experimental design measured the wake velocities in the Trefftz plane behind four bats flying over a range of speeds (3-7 m s(-1)). We computed the aerodynamic power contained in the wake using a novel interpolation method and compared these results with the power predicted by Pennycuick's and Rayner's models. The measured aerodynamic power falls between the two theoretical predictions, demonstrating that the models effectively predict the appropriate range of flight power, but the models do not accurately predict minimum power or maximum range speeds. Mechanical efficiency--the ratio of aerodynamic power output to metabolic power input--varied from 5.9% to 9.8% for the same individuals, changing with flight speed.
Project description:The major histocompatibility complex (MHC) is one of the most diverse genetic regions under pathogen-driven selection because of its central role in antigen binding and immunity. The highest MHC variability, both in terms of the number of individual alleles and gene copies, has so far been found in passerine birds; this is probably attributable to passerine adaptation to both a wide geographic range and a diverse array of habitats. If extraordinary high MHC variation and duplication rates are adaptive features under selection during the evolution of ecologically and taxonomically diverse species, then similarly diverse MHC architectures should be found in bats. Bats are an extremely species-rich mammalian group that is globally widely distributed. Many bat species roost in multitudinous groups and have high contact rates with pathogens, conspecifics, and allospecifics. We have characterized the MHC class I diversity in 116 Panamanian Seba's short-tailed bats (Carollia perspicillata), a widely distributed, generalist, neotropical species. We have detected a remarkable individual and population-level diversity of MHC class I genes, with between seven and 22 alleles and a unique genotype in each individual. This diversity is comparable with that reported in passerine birds and, in both taxonomic groups, further variability has evolved through length polymorphisms. Our findings support the hypothesis that, for species with a geographically broader range, high MHC class I variability is particularly adaptive. Investigation of the details of the underlying adaptive processes and the role of the high MHC diversity in pathogen resistance are important next steps for a better understanding of the role of bats in viral evolution and as carriers of several deadly zoonotic viruses.