Items 1-20 of 311

    • Journal Article

      Perspective review of optical imaging in welfare assessment in animal-based research 

      Pereira, Carina Barbosa; Kunczik, Janosch; Bleich, André; Haeger, Christine; Kiessling, Fabian; Thum, Thomas; Tolba, René; Lindauer, Ute; Treue, Stefan; Czaplik, Michael
      Journal of Biomedical Optics 2019; 24: Art. 070601
      To refine animal research, vital signs, activity, stress, and pain must be monitored. In chronic studies, some measures can be assessed using telemetry sensors. Although this methodology provides high-precision data, an initial surgery for device implantation is necessary, potentially leading to stress, wound infections, and restriction of motion. Recently, camera systems have been adapted for animal research. We give an overview of parameters that can be assessed using imaging in the visible, near-infrared, and thermal spectrum of light. It focuses on heart activity, respiration, oxygen saturation, and motion, as well as on wound analysis. For each parameter, we offer recommendations on the minimum technical requirements of appropriate systems, regions of interest, and light conditions, among others. In general, these systems demonstrate great performance. For heart and respiratory rate, the error was <4  beats  /  min and 5 breaths/min. Furthermore, the systems are capable of tracking animals during different behavioral tasks. Finally, studies indicate that inhomogeneous temperature distribution around wounds might be an indicator of (pending) infections. In sum, camera-based techniques have several applications in animal research. As vital parameters are currently only assessed in sedated animals, the next step should be the integration of these modalities in home-cage monitoring.
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    • Journal Article

      Spider Monkeys in Human-Modified Landscapes 

      Arroyo-Rodríguez, Víctor; Pérez-Elissetche, Gloria Karina; Ordóñez-Gómez, José D.; González-Zamora, Arturo; Chaves, Óscar M.; Sánchez-López, Sònia; Chapman, Colin A.; Morales-Hernández, Karenina; Pablo-Rodríguez, Miriam; Ramos-Fernández, Gabriel
      Tropical Conservation Science 2016; 10 p.1-13
      With the extant of tropical forest degradation, primates increasingly inhabit forest patches embedded in anthropogenic matrices. Such matrices are composed of different land cover types (e.g., agricultural lands and cattle pastures), but large uncertainty remains about the ability of primates to use these land covers. Here, we assessed the use of the landscape matrix by spider monkeys (Ateles geoffroyi) in 13 forest sites from three countries (Mexico, Costa Rica, and El Salvador). Based on ad libitum records from >212 months of field observations, we found that spider monkeys used four types of land covers for feeding or traveling: secondary vegetation, isolated trees, tree crops, and vegetation corridors. Secondary vegetation was more frequently used than the other land covers. The number of land covers present in the matrix was positively related to the number of land covers used for traveling and feeding. Monkeys consumed 53 plant species in the matrix, mostly native and old-growth or late-successional forest species, although they also used three cultivated tree species. Most species were trees, especially from preferred food species, although monkeys also used palms, lianas, and shrubs. Monkeys fed principally from fruits, but they also used leaves, wood, and flowers. Most species were used from secondary vegetation and isolated trees. These findings suggest that the landscape matrix can provide supplementary food sources for this endangered primate and opportunities for traveling (i.e., spatial connectivity) in human-modified landscapes—information that can be used to improve conservation strategies, especially under the context of land-sharing management strategies (e.g., agroforestry).
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    • Journal Article

      Highly variable lifespan in an annual reptile, Labord’s chameleon (Furcifer labordi) 

      Eckhardt, Falk; Kappeler, Peter M.; Kraus, Cornelia
      Scientific Reports 2017; 7(1)
      Among tetrapods, the current record holder for shortest lifespan is Labord's chameleon, Furcifer labordi. These reptiles from the arid southwest of Madagascar have a reported lifespan of 4-5 months during the annual rainy season and spend the majority of their life (8-9 months) as a developing embryo. This semelparous, annual life history is unique among tetrapods, but only one population (Ranobe) in the southernmost distribution range has been studied. We therefore investigated the potential for environmentally-dependent variability in lifespan in a population in Kirindy Forest, which has a much longer warm rainy season. While no adults were found after March in Ranobe, the disappearance of adults was delayed by several months in Kirindy. Our data also revealed sex-biased mortality, suggesting that females have a longevity advantage. Furthermore, we found that, after an unusually long previous rainy season, one female was capable of surviving until a second breeding season. Keeping F. labordi in cages under ambient conditions demonstrated that also males can also survive until the next season of activity under these conditions. Our study therefore revealed considerable variability in the extreme life history of this tetrapod that is linked to variation in ecological factors.
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    • Journal Article

      Strategic deployment of feature-based attentional gain in primate visual cortex 

      Kozyrev, Vladislav; Daliri, Mohammad Reza; Schwedhelm, Philipp; Treue, Stefan
      PLOS Biology 2019; 17(8): Art. e3000387
      Attending to visual stimuli enhances the gain of those neurons in primate visual cortex that preferentially respond to the matching locations and features (on-target gain). Although this is well suited to enhance the neuronal representation of attended stimuli, it is nonoptimal under difficult discrimination conditions, as in the presence of similar distractors. In such cases, directing attention to neighboring neuronal populations (off-target gain) has been shown to be the most efficient strategy, but although such a strategic deployment of attention has been shown behaviorally, its underlying neural mechanisms are unknown. Here, we investigated how attention affects the population responses of neurons in the middle temporal (MT) visual area of rhesus monkeys to bidirectional movement inside the neurons' receptive field (RF). The monkeys were trained to focus their attention onto the fixation spot or to detect a direction or speed change in one of the motion directions (the "target"), ignoring the distractor motion. Population activity profiles were determined by systematically varying the patterns' directions while maintaining a constant angle between them. As expected, the response profiles show a peak for each of the 2 motion directions. Switching spatial attention from the fixation spot into the RF enhanced the peak representing the attended stimulus and suppressed the distractor representation. Importantly, the population data show a direction-dependent attentional modulation that does not peak at the target feature but rather along the slopes of the activity profile representing the target direction. Our results show that attentional gains are strategically deployed to optimize the discriminability of target stimuli, in line with an optimal gain mechanism proposed by Navalpakkam and Itti.
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    • Journal Article

      Modulation of HIV-1 Gag/Gag-Pol frameshifting by tRNA abundance 

      Korniy, Natalia; Goyal, Akanksha; Hoffmann, Markus; Samatova, Ekaterina; Peske, Frank; Pöhlmann, Stefan; Rodnina, Marina V.
      Nucleic Acids Research 2019; 47(10) p.5210-5222
      A hallmark of translation in human immunodeficiency virus type 1 (HIV-1) is a -1 programmed ribosome frameshifting event that produces the Gag-Pol fusion polyprotein. The constant Gag to Gag-Pol ratio is essential for the virion structure and infectivity. Here we show that the frameshifting efficiency is modulated by Leu-tRNALeu that reads the UUA codon at the mRNA slippery site. This tRNALeu isoacceptor is particularly rare in human cell lines derived from T-lymphocytes, the cells that are targeted by HIV-1. When UUA decoding is delayed, the frameshifting follows an alternative route, which maintains the Gag to Gag-Pol ratio constant. A second potential slippery site downstream of the first one is normally inefficient but can also support -1-frameshifting when altered by a compensatory resistance mutation in response to current antiviral drug therapy. Together these different regimes allow the virus to maintain a constant -1-frameshifting efficiency to ensure successful virus propagation.
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    • Journal Article

      Long-tailed macaques extract statistical information from repeated types of events to make rational decisions under uncertainty 

      Placì, Sarah; Padberg, Marie; Rakoczy, Hannes; Fischer, Julia
      Scientific Reports 2019; 9(1): Art. 12107
      Human children and apes seem to be intuitive statisticians when making predictions from populations of objects to randomly drawn samples, whereas monkeys seem not to be. Statistical reasoning can also be investigated in tasks in which the probabilities of different possibilities must be inferred from relative frequencies of events, but little is known about the performance of nonhuman primates in such tasks. In the current study, we investigated whether long-tailed macaques extract statistical information from repeated types of events to make predictions under uncertainty. In each experiment, monkeys first experienced the probability of rewards associated with different factors separately. In a subsequent test trial, monkeys could then choose between the different factors presented simultaneously. In Experiment 1, we tested whether long-tailed macaques relied on probabilities and not on a comparison of absolute quantities to make predictions. In Experiment 2 and 3 we varied the nature of the predictive factors and the complexity of the covariation structure between rewards and factors. Results indicate that long-tailed macaques extract statistical information from repeated types of events to make predictions and rational decisions under uncertainty, in more or less complex scenarios. These findings suggest that the presentation format affects the monkeys' statistical reasoning abilities.
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    • Journal Article

      Routing information flow by separate neural synchrony frequencies allows for “functionally labeled lines” in higher primate cortex 

      Khamechian, Mohammad Bagher; Kozyrev, Vladislav; Treue, Stefan; Esghaei, Moein; Daliri, Mohammad Reza
      Proceedings of the National Academy of Sciences 2019; 116(25) p.12506-12515
      Efficient transfer of sensory information to higher (motor or associative) areas in primate visual cortical areas is crucial for transforming sensory input into behavioral actions. Dynamically increasing the level of coordination between single neurons has been suggested as an important contributor to this efficiency. We propose that differences between the functional coordination in different visual pathways might be used to unambiguously identify the source of input to the higher areas, ensuring a proper routing of the information flow. Here we determined the level of coordination between neurons in area MT in macaque visual cortex in a visual attention task via the strength of synchronization between the neurons' spike timing relative to the phase of oscillatory activities in local field potentials. In contrast to reports on the ventral visual pathway, we observed the synchrony of spikes only in the range of high gamma (180 to 220 Hz), rather than gamma (40 to 70 Hz) (as reported previously) to predict the animal's reaction speed. This supports a mechanistic role of the phase of high-gamma oscillatory activity in dynamically modulating the efficiency of neuronal information transfer. In addition, for inputs to higher cortical areas converging from the dorsal and ventral pathway, the distinct frequency bands of these inputs can be leveraged to preserve the identity of the input source. In this way source-specific oscillatory activity in primate cortex can serve to establish and maintain "functionally labeled lines" for dynamically adjusting cortical information transfer and multiplexing converging sensory signals.
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    • Journal Article

      One size fits all? Relationships among group size, health, and ecology indicate a lack of an optimal group size in a wild lemur population 

      Rudolph, Katja; Fichtel, Claudia; Schneider, Dominik; Heistermann, Michael; Koch, Flávia; Daniel, Rolf; Kappeler, Peter M.
      Behavioral Ecology and Sociobiology 2019; 73(9): Art. 132
      Group size is a key component of sociality and can affect individual health and fitness. However, proximate links explaining this relationship remain poorly understood, partly because previous studies neglected potential confounding effects of ecological factors. Here, we correlated group size with various measures of health while controlling for measures of seasonality and habitat quality, to explore trade-offs related to group living in a mainly folivorous primate—Verreaux’s sifakas (Propithecus verreauxi). Over a course of 2 years, we studied 42 individuals of 7 differently sized groups (range 2–10) and combined measures of faecal glucocorticoid metabolites (n > 2300 samples), parasitism (n > 500 samples), ranging and activity patterns, together with estimates of habitat quality (measures of ~ 7000 feeding trees). None of our measures was correlated with group size, while seasonality, but not habitat quality, impacted almost all examined variables. We conclude that group size alone might be insufficient to explain patterns in the sociality-health nexus or that the small range of group sizes in this species does not induce effects suggested for species living in larger groups. An optimal group size balancing the advantages and disadvantages of living in differently sized groups may not exist for Verreaux’s sifakas. Our results do not support predictions of the ecological constraints hypothesis or the optimal group size hypothesis as they may only account for species limited in group size by ecological factors—a condition that may not apply to the majority of folivorous mammals, which seem to be limited by social factors.
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    • Journal Article

      Small Neotropical primates promote the natural regeneration of anthropogenically disturbed areas 

      Heymann, Eckhard W.; Culot, Laurence; Knogge, Christoph; Smith, Andrew C.; Tirado Herrera, Emérita R.; Müller, Britta; Stojan-Dolar, Mojca; Lledo Ferrer, Yvan; Kubisch, Petra; Kupsch, Denis; et al.
      Slana, DarjaKoopmann, Mareike LenaZiegenhagen, BirgitBialozyt, RonaldMengel, ChristinaHambuckers, JulienHeer, Katrin
      Scientific Reports 2019; 9(1): Art. 10356
      Increasingly large proportions of tropical forests are anthropogenically disturbed. Where natural regeneration is possible at all, it requires the input of plant seeds through seed dispersal from the forest matrix. Zoochorous seed dispersal - the major seed dispersal mode for woody plants in tropical forests - is particularly important for natural regeneration. In this study, covering a period of more than 20 years, we show that small New World primates, the tamarins Saguinus mystax and Leontocebus nigrifrons, increase their use of an anthropogenically disturbed area over time and disperse seeds from primary forest tree species into this area. Through monitoring the fate of seeds and through parentage analyses of seedlings of the legume Parkia panurensis from the disturbed area and candidate parents from the primary forest matrix, we show that tamarin seed dispersal is effective and contributes to the natural regeneration of the disturbed area.
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    • Journal Article

      Is implicit Theory of Mind real but hard to detect? Testing adults with different stimulus materials 

      Kulke, Louisa; Wübker, Marieke; Rakoczy, Hannes
      Royal Society Open Science 2019; 6(7): Art. 190068
      Recently, Theory of Mind (ToM) research has been revolutionized by new methods. Eye-tracking studies measuring subjects' looking times or anticipatory looking have suggested that implicit and automatic forms of ToM develop much earlier in ontogeny than traditionally assumed and continue to operate outside of subjects’ awareness throughout the lifespan. However, the reliability of these implicit methods has recently been put into question by an increasing number of non-replications. What remains unclear from these accumulating non-replication findings, though, is whether they present true negatives (there is no robust phenomenon of automatic ToM) or false ones (automatic ToM is real but difficult to tap). In order to address these questions, the current study implemented conceptual replications of influential anticipatory looking ToM tasks with a new variation in the stimuli. In two separate preregistered studies, we used increasingly realistic stimuli and controlled for potential confounds. Even with these more realistic stimuli, previous results could not be replicated. Rather, the anticipatory looking pattern found here remained largely compatible with more parsimonious explanations. In conclusion, the reality and robustness of automatic ToM remains controversial.
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    • Journal Article

      Pro-Angiogenic Macrophage Phenotype to Promote Myocardial Repair 

      Ferraro, Bartolo; Leoni, Giovanna; Hinkel, Rabea; Ormanns, Steffen; Paulin, Nicole; Ortega-Gomez, Almudena; Viola, Joana R.; de Jong, Renske; Bongiovanni, Dario; Bozoglu, Tarik; et al.
      Maas, Sanne L.D’Amico, MicheleKessler, ThorstenZeller, TanjaHristov, MichaelReutelingsperger, ChrisSager, Hendrik B.Döring, YvonneNahrendorf, MatthiasKupatt, ChristianSoehnlein, Oliver
      Journal of the American College of Cardiology 2019; 73(23) p.2990-3002
      BACKGROUND: Heart failure following myocardial infarction (MI) remains one of the major causes of death worldwide, and its treatment is a crucial challenge of cardiovascular medicine. An attractive therapeutic strategy is to stimulate endogenous mechanisms of myocardial regeneration. OBJECTIVES: This study evaluates the potential therapeutic treatment with annexin A1 (AnxA1) to induce cardiac repair after MI. METHODS: AnxA1 knockout (AnxA1-/-) and wild-type mice underwent MI induced by ligation of the left anterior descending coronary artery. Cardiac functionality was assessed by longitudinal echocardiographic measurements. Histological, fluorescence-activated cell sorting, dot blot analysis, and in vitro/ex vivo studies were used to assess the myocardial neovascularization, macrophage content, and activity in response to AnxA1. RESULTS: AnxA1-/- mice showed a reduced cardiac functionality and an expansion of proinflammatory macrophages in the ischemic area. Cardiac macrophages from AnxA1-/- mice exhibited a dramatically reduced ability to release the proangiogenic mediator vascular endothelial growth factor (VEGF)-A. However, AnxA1 treatment enhanced VEGF-A release from cardiac macrophages, and its delivery in vivo markedly improved cardiac performance. The positive effect of AnxA1 treatment on cardiac performance was abolished in wild-type mice transplanted with bone marrow derived from Cx3cr1creERT2Vegfflox/flox or in mice depleted of macrophages. Similarly, cardioprotective effects of AnxA1 were obtained in pigs in which full-length AnxA1 was overexpressed by use of a cardiotropic adeno-associated virus. CONCLUSIONS: AnxA1 has a direct action on cardiac macrophage polarization toward a pro-angiogenic, reparative phenotype. AnxA1 stimulated cardiac macrophages to release high amounts of VEGF-A, thus inducing neovascularization and cardiac repair.
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    • Journal Article

      Future Directions for Personality Research: Contributing New Insights to the Understanding of Animal Behavior 

      Wilson, Vanessa; Guenther, Anja; Øverli, Øyvind; Seltmann, Martin W.; Altschul, Drew
      Animals 2019; 9(5): Art. 240
      As part of the European Conference on Behavioral Biology 2018, we organized a symposium entitled, "Animal personality: providing new insights into behavior?" The aims of this symposium were to address current research in the personality field, spanning both behavioral ecology and psychology, to highlight the future directions for this research, and to consider whether differential approaches to studying behavior contribute something new to the understanding of animal behavior. In this paper, we discuss the study of endocrinology and ontogeny in understanding how behavioral variation is generated and maintained, despite selection pressures assumed to reduce this variation. We consider the potential mechanisms that could link certain traits to fitness outcomes through longevity and cognition. We also address the role of individual differences in stress coping, mortality, and health risk, and how the study of these relationships could be applied to improve animal welfare. From the insights provided by these topics, we assert that studying individual differences through the lens of personality has provided new directions in behavioral research, and we encourage further research in these directions, across this interdisciplinary field.
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    • Journal Article

      Species-Specific Conservation of Linear Antigenic Sites on Vaccinia Virus A27 Protein Homologs of Orthopoxviruses 

      Ahsendorf, Henrike; Gan, Li; Eltom, Kamal; Abd El Wahed, Ahmed; Hotop, Sven-Kevin; Roper, Rachel; Beutling, Ulrike; Broenstrup, Mark; Stahl-Hennig, Christiane; Hoelzle, Ludwig; et al.
      Czerny, Claus-Peter
      Viruses 2019; 11(6): Art. 493
      The vaccinia virus (VACV) A27 protein and its homologs, which are found in a large number of members of the genus Orthopoxvirus (OPXV), are targets of viral neutralization by host antibodies. We have mapped six binding sites (epitopes #1A: aa 32-39, #1B: aa 28-33, #1C: aa 26-31, #1D: 28-34, #4: aa 9-14, and #5: aa 68-71) of A27 specific monoclonal antibodies (mAbs) using peptide arrays. MAbs recognizing epitopes #1A-D and #4 neutralized VACV Elstree in a complement dependent way (50% plaque-reduction: 12.5-200 µg/mL). Fusion of VACV at low pH was blocked through inhibition of epitope #1A. To determine the sequence variability of the six antigenic sites, 391 sequences of A27 protein homologs available were compared. Epitopes #4 and #5 were conserved among most of the OPXVs, while the sequential epitope complex #1A-D was more variable and, therefore, responsible for species-specific epitope characteristics. The accurate and reliable mapping of defined epitopes on immuno-protective proteins such as the A27 of VACV enables phylogenetic studies and insights into OPXV evolution as well as to pave the way to the development of safer vaccines and chemical or biological antivirals.
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    • Journal Article

      Ultrafast optogenetic stimulation of the auditory pathway by targeting‐optimized Chronos 

      Keppeler, Daniel; Merino, Ricardo Martins; Lopez de la Morena, David; Bali, Burak; Huet, Antoine Tarquin; Gehrt, Anna; Wrobel, Christian; Subramanian, Swati; Dombrowski, Tobias; Wolf, Fred; et al.
      Rankovic, VladanNeef, AndreasMoser, Tobias
      The EMBO Journal 2018; 37(24): Art. e99649
      Optogenetic tools, providing non‐invasive control over selected cells, have the potential to revolutionize sensory prostheses for humans. Optogenetic stimulation of spiral ganglion neurons (SGNs) in the ear provides a future alternative to electrical stimulation used in cochlear implants. However, most channelrhodopsins do not support the high temporal fidelity pertinent to auditory coding because they require milliseconds to close after light‐off. Here, we biophysically characterized the fast channelrhodopsin Chronos and revealed a deactivation time constant of less than a millisecond at body temperature. In order to enhance neural expression, we improved its trafficking to the plasma membrane (Chronos‐ES/TS). Following efficient transduction of SGNs using early postnatal injection of the adeno‐associated virus AAV‐PHP.B into the mouse cochlea, fiber‐based optical stimulation elicited optical auditory brainstem responses (oABR) with minimal latencies of 1 ms, thresholds of 5 μJ and 100 μs per pulse, and sizable amplitudes even at 1,000 Hz of stimulation. Recordings from single SGNs demonstrated good temporal precision of light‐evoked spiking. In conclusion, efficient virus‐mediated expression of targeting‐optimized Chronos‐ES/TS achieves ultrafast optogenetic control of neurons.
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    • Journal Article

      Guanylate-Binding Proteins 2 and 5 Exert Broad Antiviral Activity by Inhibiting Furin-Mediated Processing of Viral Envelope Proteins 

      Braun, Elisabeth; Hotter, Dominik; Koepke, Lennart; Zech, Fabian; Groß, Rüdiger; Sparrer, Konstantin M.J.; Müller, Janis A.; Pfaller, Christian K.; Heusinger, Elena; Wombacher, Rebecka; et al.
      Sutter, KathrinDittmer, UlfWinkler, MichaelSimmons, GrahamJakobsen, Martin R.Conzelmann, Karl-KlausPöhlmann, StefanMünch, JanFackler, Oliver T.Kirchhoff, FrankSauter, Daniel
      Cell Reports 2019; 27(7): Art. 2104.e10
      Guanylate-binding protein (GBP) 5 is an interferon (IFN)-inducible cellular factor reducing HIV-1 infectivity by an incompletely understood mechanism. Here, we show that this activity is shared by GBP2, but not by other members of the human GBP family. GBP2/5 decrease the activity of the cellular proprotein convertase furin, which mediates conversion of the HIV-1 envelope protein (Env) precursor gp160 into mature gp120 and gp41. Because this process primes HIV-1 Env for membrane fusion, viral particles produced in the presence of GBP2/5 are poorly infectious due to increased incorporation of non-functional gp160. Furin activity is critical for the processing of envelope glycoproteins of many viral pathogens. Consistently, GBP2/5 also inhibit Zika, measles, and influenza A virus replication and decrease infectivity of viral particles carrying glycoproteins of Marburg and murine leukemia viruses. Collectively, our results show that GPB2/5 exert broad antiviral activity by suppressing the activity of the virus-dependency factor furin.
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    • Journal Article

      Catalyzing Transitions to Sociality: Ecology Builds on Parental Care 

      Socias-Martínez, Lluís; Kappeler, Peter M.
      Frontiers in Ecology and Evolution 2019; 7: Art. 160
      In the context of social evolution research, great emphasis on kin-selected benefits has led to an understanding of parental care as one of the activities that helpers can perform in extended cooperative families. Nevertheless, this perspective might have precluded a deeper understanding of the implications of parental care for social evolution. We argue that parental care is a broader set of processes playing a key role both before and during the emergence of sociality. The care system of a species may be understood as the result of long coevolutionary processes with environmental pressures during presocial stages that impact transitions to sociality. We evaluate the present framework against evidence on the evolution of parental care and transitions toward sociality in subsocial and parasocial vertebrate and invertebrate species. Moreover, following previous evidence for the importance of modes of foraging and resting, we structure our inquiry by classifying societies into three types. Our results suggest that in “central place foragers” and “fortress defenders”, ecological factors promoting the evolution of parental care foster a set of coevolutionary feedback loops resulting in increases in parental effort and offspring needs. Offspring needs alone or in combination with limited breeding options enhance the relative benefits of positive social interactions, catalyzing transitions to sociality. In “itinerant foragers”, sociality is associated with colonizing new niches. Changes in predation pressure entail changes in the modes of care or selection for certain types of care already present in solitary ancestors. Further changes in the form of collective defense may be needed for permanent sociality to evolve. We conclude that there is evidence that social transitions to different types of societies are the result of long coevolutionary processes between environmental pressures and the care systems in a wide variety of taxa. Therefore, advances in the study of the origins of sociality may require further investigation of parental care evolution in solitary ancestors of today’s social species.
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    • Journal Article

      Thalamus exhibits less sensory variability quenching than cortex 

      Poland, E.; Donner, T. H.; Müller, K. -M.; Leopold, D. A.; Wilke, M.
      Scientific Reports 2019; 9(1): Art. 7590
      Spiking activity exhibits a large degree of variability across identical trials, which has been shown to be significantly reduced by stimulus onset in a wide range of cortical areas. Whether similar dynamics apply to the thalamus and in particular to the pulvinar is largely unknown. Here, we examined electrophysiological recordings from two adult rhesus macaques performing a perceptual task and comparatively investigated trial-to-trial variability in higher-order thalamus (ventral and dorsal pulvinar), the lateral geniculate nucleus (LGN) and visual cortex (area V4) prior to and following the presentation of a visual stimulus. We found spiking variability during stable fixation prior to stimulus onset to be considerably lower in both pulvinar and the LGN as compared to area V4. In contrast to the prominent variability reduction in V4 upon stimulus onset, variability in the thalamic nuclei was largely unaffected by visual stimulation. There was a small but significant variability decrease in the dorsal pulvinar, but not in the ventral portion of the pulvinar, which is closely connected to visual cortices and would thus have been expected to reflect cortical response properties. This dissociation did not stem from differences in response strength or mean firing rates and indicates fundamental differences in variability quenching between thalamus and cortex.
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    • Journal Article

      Right on track? Performance of satellite telemetry in terrestrial wildlife research 

      Hofman, M. P. G.; Hayward, M. W.; Heim, M.; Marchand, P.; Rolandsen, C. M.; Mattisson, J.; Urbano, F.; Heurich, M.; Mysterud, A.; Melzheimer, J.; et al.
      Morellet, N.Voigt, U.Allen, B. L.Gehr, B.Rouco, C.Ullmann, W.Holand, Ø.Jørgensen, N. H.Steinheim, G.Cagnacci, F.Kroeschel, M.Kaczensky, P.Buuveibaatar, B.Payne, J. C.Palmegiani, I.Jerina, K.Kjellander, P.Johansson, Ö.LaPoint, S.Bayrakcismith, R.Linnell, J. D. C.Zaccaroni, M.Jorge, M. L. S.Oshima, J. E. F.Songhurst, A.Fischer, C.Mc Bride, R. T.Thompson, J. J.Streif, S.Sandfort, R.Bonenfant, C.Drouilly, M.Klapproth, M.Zinner, D.Yarnell, R.Stronza, A.Wilmott, L.Meisingset, E.Thaker, M.Vanak, A. T.Nicoloso, S.Graeber, R.Said, S.Boudreau, M. R.Devlin, A.Hoogesteijn, R.May-Junior, J. A.Nifong, J. C.Odden, J.Quigley, H. B.Tortato, F.Parker, D. M.Caso, A.Perrine, J.Tellaeche, C.Zieba, F.Zwijacz-Kozica, T.Appel, C. L.Axsom, I.Bean, W. T.Cristescu, B.Périquet, S.Teichman, K. J.Karpanty, S.Licoppe, A.Menges, V.Black, K.Scheppers, T. L.Schai-Braun, S. C.Azevedo, F. C.Lemos, F. G.Payne, A.Swanepoel, L. H.Weckworth, B. V.Berger, A.Bertassoni, A.McCulloch, G.Šustr, P.Athreya, V.Bockmuhl, D.Casaer, J.Ekori, A.Melovski, D.Richard-Hansen, C.van de Vyver, D.Reyna-Hurtado, R.Robardet, E.Selva, N.Sergiel, A.Farhadinia, M. S.Sunde, P.Portas, R.Ambarli, H.Berzins, R.Kappeler, P. M.Mann, G. K.Pyritz, L.Bissett, C.Grant, T.Steinmetz, R.Swedell, L.Welch, R. J.Armenteras, D.Bidder, O. R.González, T. M.Rosenblatt, A.Kachel, S.Balkenhol, N.
      PLOS ONE 2019; 14(5): Art. e0216223
      Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.
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    • Journal Article

      Near physiological spectral selectivity of cochlear optogenetics 

      Dieter, Alexander; Duque-Afonso, Carlos J.; Rankovic, Vladan; Jeschke, Marcus; Moser, Tobias
      Nature Communications 2019; 10(1): Art. 1962
      Cochlear implants (CIs) electrically stimulate spiral ganglion neurons (SGNs) and partially restore hearing to half a million CI users. However, wide current spread from intracochlear electrodes limits spatial selectivity (i.e. spectral resolution) of electrical CIs. Optogenetic stimulation might become an alternative, since light can be confined in space, promising artificial sound encoding with increased spectral selectivity. Here we compare spectral selectivity of optogenetic, electric, and acoustic stimulation by multi-channel recordings in the inferior colliculus (IC) of gerbils. When projecting light onto tonotopically distinct SGNs, we observe corresponding tonotopically ordered IC activity. An activity-based comparison reveals that spectral selectivity of optogenetic stimulation is indistinguishable from acoustic stimulation for modest intensities. Moreover, optogenetic stimulation outperforms bipolar electric stimulation at medium and high intensities and monopolar electric stimulation at all intensities. In conclusion, we demonstrate better spectral selectivity of optogenetic over electric SGN stimulation, suggesting the potential for improved hearing restoration by optical CIs.
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    • Journal Article

      Acoustic variation of spider monkey (Ateles geoffroyi) contact calls is related to caller isolation and affects listeners’ responses 

      Ordóñez-Gómez, José D.; Santillan-Doherty, Ana M.; Hammerschmidt, Kurt
      PLOS ONE 2019; 14(4): Art. e0213914
      Group living animals produce vocalizations denominated "contact calls" to maintain contact with out-of-sight group members. These calls have been shown to vary with caller identity and distance to potential listeners. However, it is not clear whether the acoustic variation of contact calls is related to caller social isolation (e.g., inside or outside a subgroup) and listeners' responses that can be helpful to maintain contact. Here, we addressed these questions in spider monkeys (Ateles geoffroyi), a Neotropical primate that exchanges contact calls denominated "whinnies", which show graded variation related to caller immediate behavior and distance between callers. Using 566 whinnies produced by 35 free-ranging adult spider monkeys recorded at ≤ 20 m from microphones, we first analyzed whether the acoustic variation of spontaneous whinnies (i.e., whinnies that are not responses to previous whinnies) is related to caller social isolation or whether acoustic variation is related to the likelihood of eliciting a response whinny from another individual. Secondly, we assessed whether listeners' responses (i.e., time to respond vocally, acoustic characteristics of response whinnies, orienting behaviors) were related to the acoustic variation of previous whinnies. Our study revealed that callers that were outside a subgroup produced whinnies with a lower fundamental frequency (F0), which travels longer distances, and increases the likelihood of producing a response whinny. Moreover, listeners (i.e., responders) responded faster to lower F0 whinnies. However, the acoustic variation (i.e., F0 variation) in response whinnies was better explained by the separation distance between callers, than by the acoustic variation of the previous whinny. Overall, our results suggest that whinny variation facilitates vocal contact to callers that are outside a subgroup, and that context and whinny variation affect listeners' responses.
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