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Eli Geffen - One of the best experts on this subject based on the ideXlab platform.
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Sexually opposite effects of testosterone on mating success in wild Rock Hyrax
Behavioral Ecology, 2019Co-Authors: Lee Koren, Amiyaal Ilany, Adi Barocas, Yishai Weissman, Inbar Schnitzer, Rosanne Beukeboom, Vlad Demartsev, Eli GeffenAbstract:Abstract Although males and females share traits, their motivations and needs may be different, due to life-history disparities that lead to divergent selection pressures. Proximate mechanisms underlying differences between the sexes include hormones that mediate the development and activation of suites of traits. Testosterone is associated with morphological features, physiological processes, and social behaviors in both sexes. However, even if present in similar concentrations in the circulation, testosterone often affects males and females differently. We combined behavioral mating observations of the wild polygynandrous Rock Hyrax (Procavia capensis) with hair testosterone that represents long-term integrated levels. We found that whereas copulation success increases with the rise in testosterone in males it decreases in females. We did not find an association between testosterone and choosiness in either sex. However, we found that males with higher testosterone mate-guarded females with lower testosterone. Our findings show disassortative mating and mate-guarding in respect to testosterone and provide clues to the cost of testosterone for females, in terms of copulation success. These results open up intriguing questions relating to the role of testosterone in mediating a similar trade-off in male and female reproductive success.
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a mixed strategy of counter singing behavior in male Rock Hyrax vocal competitions
Behavioral Ecology and Sociobiology, 2016Co-Authors: Vlad Demartsev, Amiyaal Ilany, Adi Barocas, Lee Koren, Inbar Schnitzer, Eli GeffenAbstract:Maynard-Smith’s game-theoretical framework suggests that conflicts should be resolved through an exchange of agonistic displays which can be as effective as physical attack in securing contested resources. Hence, participants use signaling tactics that are governed by game-theoretical competition rules to maximize their benefit from the interaction. In Rock Hyraxes, males initiate singing in response to conspecific male songs, possibly to self-advertise and to facilitate comparison of performance by receivers. We hypothesized that Hyrax counter-singing strategy can be explained by resident-intruder model and its outcome is determined by the identity and ability of the participants. Natural Hyrax singing events and playback-induced events were classified according to the participants’ residence status—resident or bachelor (i.e., non-resident). As predicted by the resident-intruder model, resident listeners tended to reply to conspecific males at high rates (≈40 %), while bachelors showed low reply rates (17 %) to resident initiators. Unexpectedly, the lowest-ranking bachelors showed a tendency to reply to the highest-ranking residents. One possible explanation for this counter-intuitive behavior might be that weaker individuals exploit a situation in which it is unremunerated for a stronger opponent to retaliate (i.e., Napoleon strategy) and seize a self-advertisement opportunity in front of a large audience attending to the high-ranking males’ signal. Overall, we show that male Hyraxes employ different counter-singing tactics depending on the residence and rank differences between the participants. This choice of competition tactics can be based on opponents’ individual recognition or/and on direct decoding of opponents’ traits encoded in the song. In nature, conflicts are usually resolved through signaling rather than by actual fighting. Rock Hyrax males often participate in vocal competitions, possibly to reduce the need for physical confrontations. During our study on the dynamics of male Hyrax vocal competition, we discovered that Hyraxes employ mixed counter-singing strategy dependent on the residence status and social rank differences between the participants. A paradoxical “Napoleon-complex” tactic was observed in interactions between males, when low ranking bachelors were found to interact and challenge the highest-ranking residents. On the other hand, residents were found to interact with opponents regardless of residency and/or rank. On top of the cognitive abilities required to individually recognize an opponent and possibly decode its vocal signals, our results suggest that male Hyraxes compare own individual traits to those of the opponent in a mutual signal assessment interaction.
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harsh vocal elements affect counter singing dynamics in male Rock Hyrax
Behavioral Ecology, 2016Co-Authors: Vlad Demartsev, Lee Koren, Uria Shani, Yael Goll, Eli GeffenAbstract:Morton’s motivation-structural (MS) rules suggest that the acoustic structure of a signal can reflect the caller’s motivation and internal state. In many species, low-frequency and noisy (harsh) sounds have been found to comply with MS rules, accompanying agonistic interactions and functioning as a badge of aggression and dominance. Male Rock Hyraxes (Procavia capensis) often produce long and complex advertisement calls (songs) both "spontaneously" and in counter-singing sessions with other males. Hyrax songs include a "snort" vocal element, which is a harsh sound produced only by mature, dominant males. We predicted that the number of snort elements in the song would affect the dynamics of male Hyrax counter-singing. We performed 3 series of playback experiments of natural and artificially manipulated songs on a wild Hyrax population. We found that the probability of initiating counter-singing by nearby males increased together with the number of snorts in the stimulus song. Furthermore, the receivers replied to the synthetic "snort-only" vocal sequences at an equal rate as to their origin song as long as the snort elements maintained their original position within the signal. Our findings suggest that the snort component is one of the main information transfer channels in male Hyrax singing and can elicit conspecific singing even when isolated from other vocal elements. In addition, the position of snort elements (their temporal pattern and rhythm) bears a possible significance in keeping the overall signal meaningful. Finally, our findings support previous claims that harsh sounds constitute one of the key components in vocal communication.
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the energy cost of singing in wild Rock Hyrax males evidence for an index signal
Animal Behaviour, 2013Co-Authors: Amiyaal Ilany, Tchia Ilany, Adi Barocas, Eli GeffenAbstract:In many species individuals advertise their quality via vocal communication. Although sound production requires energy, it is still unclear to what extent vocalizing increases metabolic rate. A substantial energetic cost of vocalization may suggest that it serves as a handicap. In this study, we evaluated the energetic cost of vocalization in the context of other activities in a free-living mammal. In the Rock Hyrax, Procavia capensis, males produce loud complex songs that convey multiple types of information about the singer. We used the doubly labelled water method to estimate field metabolic rate (FMR), in males that were collar-fitted with miniaturized recorders. Higher-ranked males sang longer songs, which also featured higher sound energy. However, contrary to our predictions, the duration of singing was negatively correlated with FMR, whereas the duration of other social sounds, typically associated with social conflicts, had a positive effect on FMR. We suggest that higher-ranking males expend overall less energy due to lower intrinsic metabolism, and thus the singing duration effect on FMR is a reflection of social rank. Rock Hyrax singing is therefore assessed as requiring a high effort over a short period but not as a lengthy activity, matching the category of index signals. Singing may also serve as a handicap to the signaller, not because of its energetic cost but because it exposes the singer to potential predation. Our study is the first to record the activities and vocalizations of a free-living mammal in such detail. We discuss the costs and benefits of Hyrax songs, suggesting that singing males trade safety from predators for increasing their reputation.
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The energy cost of singing in wild Rock Hyrax males: Evidence for an index signal
Animal Behaviour, 2013Co-Authors: Amiyaal Ilany, Tchia Ilany, Adi Barocas, Michael Kam, Eli GeffenAbstract:In many species individuals advertise their quality via vocal communication. Although sound production requires energy, it is still unclear to what extent vocalizing increases metabolic rate. A substantial energetic cost of vocalization may suggest that it serves as a handicap. In this study, we evaluated the energetic cost of vocalization in the context of other activities in a free-living mammal. In the Rock Hyrax, Procavia capensis, males produce loud complex songs that convey multiple types of information about the singer. We used the doubly labelled water method to estimate field metabolic rate (FMR), in males that were collar-fitted with miniaturized recorders. Higher-ranked males sang longer songs, which also featured higher sound energy. However, contrary to our predictions, the duration of singing was negatively correlated with FMR, whereas the duration of other social sounds, typically associated with social conflicts, had a positive effect on FMR. We suggest that higher-ranking males expend overall less energy due to lower intrinsic metabolism, and thus the singing duration effect on FMR is a reflection of social rank. Rock Hyrax singing is therefore assessed as requiring a high effort over a short period but not as a lengthy activity, matching the category of index signals. Singing may also serve as a handicap to the signaller, not because of its energetic cost but because it exposes the singer to potential predation. Our study is the first to record the activities and vocalizations of a free-living mammal in such detail. We discuss the costs and benefits of Hyrax songs, suggesting that singing males trade safety from predators for increasing their reputation. © 2013 The Association for the Study of Animal Behaviour.
Lee Koren - One of the best experts on this subject based on the ideXlab platform.
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Sexually opposite effects of testosterone on mating success in wild Rock Hyrax
Behavioral Ecology, 2019Co-Authors: Lee Koren, Amiyaal Ilany, Adi Barocas, Yishai Weissman, Inbar Schnitzer, Rosanne Beukeboom, Vlad Demartsev, Eli GeffenAbstract:Abstract Although males and females share traits, their motivations and needs may be different, due to life-history disparities that lead to divergent selection pressures. Proximate mechanisms underlying differences between the sexes include hormones that mediate the development and activation of suites of traits. Testosterone is associated with morphological features, physiological processes, and social behaviors in both sexes. However, even if present in similar concentrations in the circulation, testosterone often affects males and females differently. We combined behavioral mating observations of the wild polygynandrous Rock Hyrax (Procavia capensis) with hair testosterone that represents long-term integrated levels. We found that whereas copulation success increases with the rise in testosterone in males it decreases in females. We did not find an association between testosterone and choosiness in either sex. However, we found that males with higher testosterone mate-guarded females with lower testosterone. Our findings show disassortative mating and mate-guarding in respect to testosterone and provide clues to the cost of testosterone for females, in terms of copulation success. These results open up intriguing questions relating to the role of testosterone in mediating a similar trade-off in male and female reproductive success.
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a mixed strategy of counter singing behavior in male Rock Hyrax vocal competitions
Behavioral Ecology and Sociobiology, 2016Co-Authors: Vlad Demartsev, Amiyaal Ilany, Adi Barocas, Lee Koren, Inbar Schnitzer, Eli GeffenAbstract:Maynard-Smith’s game-theoretical framework suggests that conflicts should be resolved through an exchange of agonistic displays which can be as effective as physical attack in securing contested resources. Hence, participants use signaling tactics that are governed by game-theoretical competition rules to maximize their benefit from the interaction. In Rock Hyraxes, males initiate singing in response to conspecific male songs, possibly to self-advertise and to facilitate comparison of performance by receivers. We hypothesized that Hyrax counter-singing strategy can be explained by resident-intruder model and its outcome is determined by the identity and ability of the participants. Natural Hyrax singing events and playback-induced events were classified according to the participants’ residence status—resident or bachelor (i.e., non-resident). As predicted by the resident-intruder model, resident listeners tended to reply to conspecific males at high rates (≈40 %), while bachelors showed low reply rates (17 %) to resident initiators. Unexpectedly, the lowest-ranking bachelors showed a tendency to reply to the highest-ranking residents. One possible explanation for this counter-intuitive behavior might be that weaker individuals exploit a situation in which it is unremunerated for a stronger opponent to retaliate (i.e., Napoleon strategy) and seize a self-advertisement opportunity in front of a large audience attending to the high-ranking males’ signal. Overall, we show that male Hyraxes employ different counter-singing tactics depending on the residence and rank differences between the participants. This choice of competition tactics can be based on opponents’ individual recognition or/and on direct decoding of opponents’ traits encoded in the song. In nature, conflicts are usually resolved through signaling rather than by actual fighting. Rock Hyrax males often participate in vocal competitions, possibly to reduce the need for physical confrontations. During our study on the dynamics of male Hyrax vocal competition, we discovered that Hyraxes employ mixed counter-singing strategy dependent on the residence status and social rank differences between the participants. A paradoxical “Napoleon-complex” tactic was observed in interactions between males, when low ranking bachelors were found to interact and challenge the highest-ranking residents. On the other hand, residents were found to interact with opponents regardless of residency and/or rank. On top of the cognitive abilities required to individually recognize an opponent and possibly decode its vocal signals, our results suggest that male Hyraxes compare own individual traits to those of the opponent in a mutual signal assessment interaction.
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harsh vocal elements affect counter singing dynamics in male Rock Hyrax
Behavioral Ecology, 2016Co-Authors: Vlad Demartsev, Lee Koren, Uria Shani, Yael Goll, Eli GeffenAbstract:Morton’s motivation-structural (MS) rules suggest that the acoustic structure of a signal can reflect the caller’s motivation and internal state. In many species, low-frequency and noisy (harsh) sounds have been found to comply with MS rules, accompanying agonistic interactions and functioning as a badge of aggression and dominance. Male Rock Hyraxes (Procavia capensis) often produce long and complex advertisement calls (songs) both "spontaneously" and in counter-singing sessions with other males. Hyrax songs include a "snort" vocal element, which is a harsh sound produced only by mature, dominant males. We predicted that the number of snort elements in the song would affect the dynamics of male Hyrax counter-singing. We performed 3 series of playback experiments of natural and artificially manipulated songs on a wild Hyrax population. We found that the probability of initiating counter-singing by nearby males increased together with the number of snorts in the stimulus song. Furthermore, the receivers replied to the synthetic "snort-only" vocal sequences at an equal rate as to their origin song as long as the snort elements maintained their original position within the signal. Our findings suggest that the snort component is one of the main information transfer channels in male Hyrax singing and can elicit conspecific singing even when isolated from other vocal elements. In addition, the position of snort elements (their temporal pattern and rhythm) bears a possible significance in keeping the overall signal meaningful. Finally, our findings support previous claims that harsh sounds constitute one of the key components in vocal communication.
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variance in centrality within Rock Hyrax social networks predicts adult longevity
PLOS ONE, 2011Co-Authors: Adi Barocas, Amiyaal Ilany, Lee Koren, Eli GeffenAbstract:BACKGROUND: In communal mammals the levels of social interaction among group members vary considerably. In recent years, biologists have realized that within-group interactions may affect survival of the group members. Several recent studies have demonstrated that the social integration of adult females is positively associated with infant survival, and female longevity is affected by the strength and stability of the individual social bonds. Our aim was to determine the social factors that influence adult longevity in social mammals. METHODOLOGY/PRINCIPAL FINDINGS: As a model system, we studied the social Rock Hyrax (Procavia capensis), a plural breeder with low reproductive skew, whose groups are mainly composed of females. We applied network theory using 11 years of behavioral data to quantify the centrality of individuals within groups, and found adult longevity to be inversely correlated to the variance in centrality. In other words, animals in groups with more equal associations lived longer. Individual centrality was not correlated with longevity, implying that social tension may affect all group members and not only the weakest or less connected ones. CONCLUSIONS/SIGNIFICANCE: Our novel findings support previous studies emphasizing the adaptive value of social associations and the consequences of inequality among adults within social groups. However, contrary to previous studies, we suggest that it is not the number or strength of associations that an adult individual has (i.e. centrality) that is important, but the overall configuration of social relationships within the group (i.e. centrality SD) that is a key factor in influencing longevity.
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Variance in Centrality within Rock Hyrax Social Networks Predicts Adult Longevity
PLOS ONE, 2011Co-Authors: Adi Barocas, Amiyaal Ilany, Lee Koren, Eli GeffenAbstract:Background: In communal mammals the levels of social interaction among group members vary considerably. In recent years, biologists have realized that within-group interactions may affect survival of the group members. Several recent studies have demonstrated that the social integration of adult females is positively associated with infant survival, and female longevity is affected by the strength and stability of the individual social bonds. Our aim was to determine the social factors that influence adult longevity in social mammals. Methodology/Principal Findings: As a model system, we studied the social Rock Hyrax (Procavia capensis), a plural breeder with low reproductive skew, whose groups are mainly composed of females. We applied network theory using 11 years of behavioral data to quantify the centrality of individuals within groups, and found adult longevity to be inversely correlated to the variance in centrality. In other words, animals in groups with more equal associations lived longer. Individual centrality was not correlated with longevity, implying that social tension may affect all group members and not only the weakest or less connected ones. Conclusions/Significance: Our novel findings support previous studies emphasizing the adaptive value of social associations and the consequences of inequality among adults within social groups. However, contrary to previous studies, we suggest that it is not the number or strength of associations that an adult individual has (i.e. centrality) that is important, but the overall configuration of social relationships within the group (i.e. centrality SD) that is a key factor in influencing longevity.
Nicolaas Gey C Van Pittius - One of the best experts on this subject based on the ideXlab platform.
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pulmonary infection due to the dassie bacillus mycobacterium tuberculosis complex sp in a free living dassie Rock Hyrax procavia capensis from south africa
Tuberculosis, 2008Co-Authors: Sven D C Parsons, Sarah Smith, Quinton E Martins, William G C Horsnell, Tertius A Gous, E M Streicher, Robin M Warren, Paul D Van Helden, Nicolaas Gey C Van PittiusAbstract:Summary We report a case of extensive necrogranulomatous pneumonia due to infection with the dassie bacillus ( Mycobacterium tuberculosis complex sp.) in a free-living pregnant adult female dassie (Rock Hyrax— Procavia capensis ). A juvenile female dassie from the same colony also showed a focal lesion in the lungs suggestive of mycobacterial pneumonia. Our findings indicate the widespread occurrence of the dassie bacillus in free-living dassies and suggest very high infection rates in some populations. The introduction of South African dassies into novel environments should be considered in this light.
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Pulmonary infection due to the dassie bacillus (Mycobacterium tuberculosis complex sp.) in a free-living dassie (Rock Hyrax—Procavia capensis) from South Africa
Tuberculosis, 2007Co-Authors: Sven D C Parsons, Quinton E Martins, William G C Horsnell, Tertius A Gous, E M Streicher, Robin M Warren, Paul D Van Helden, Sarah G.d. Smith, Nicolaas Gey C Van PittiusAbstract:Summary We report a case of extensive necrogranulomatous pneumonia due to infection with the dassie bacillus ( Mycobacterium tuberculosis complex sp.) in a free-living pregnant adult female dassie (Rock Hyrax— Procavia capensis ). A juvenile female dassie from the same colony also showed a focal lesion in the lungs suggestive of mycobacterial pneumonia. Our findings indicate the widespread occurrence of the dassie bacillus in free-living dassies and suggest very high infection rates in some populations. The introduction of South African dassies into novel environments should be considered in this light.
Amiyaal Ilany - One of the best experts on this subject based on the ideXlab platform.
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Sexually opposite effects of testosterone on mating success in wild Rock Hyrax
Behavioral Ecology, 2019Co-Authors: Lee Koren, Amiyaal Ilany, Adi Barocas, Yishai Weissman, Inbar Schnitzer, Rosanne Beukeboom, Vlad Demartsev, Eli GeffenAbstract:Abstract Although males and females share traits, their motivations and needs may be different, due to life-history disparities that lead to divergent selection pressures. Proximate mechanisms underlying differences between the sexes include hormones that mediate the development and activation of suites of traits. Testosterone is associated with morphological features, physiological processes, and social behaviors in both sexes. However, even if present in similar concentrations in the circulation, testosterone often affects males and females differently. We combined behavioral mating observations of the wild polygynandrous Rock Hyrax (Procavia capensis) with hair testosterone that represents long-term integrated levels. We found that whereas copulation success increases with the rise in testosterone in males it decreases in females. We did not find an association between testosterone and choosiness in either sex. However, we found that males with higher testosterone mate-guarded females with lower testosterone. Our findings show disassortative mating and mate-guarding in respect to testosterone and provide clues to the cost of testosterone for females, in terms of copulation success. These results open up intriguing questions relating to the role of testosterone in mediating a similar trade-off in male and female reproductive success.
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a mixed strategy of counter singing behavior in male Rock Hyrax vocal competitions
Behavioral Ecology and Sociobiology, 2016Co-Authors: Vlad Demartsev, Amiyaal Ilany, Adi Barocas, Lee Koren, Inbar Schnitzer, Eli GeffenAbstract:Maynard-Smith’s game-theoretical framework suggests that conflicts should be resolved through an exchange of agonistic displays which can be as effective as physical attack in securing contested resources. Hence, participants use signaling tactics that are governed by game-theoretical competition rules to maximize their benefit from the interaction. In Rock Hyraxes, males initiate singing in response to conspecific male songs, possibly to self-advertise and to facilitate comparison of performance by receivers. We hypothesized that Hyrax counter-singing strategy can be explained by resident-intruder model and its outcome is determined by the identity and ability of the participants. Natural Hyrax singing events and playback-induced events were classified according to the participants’ residence status—resident or bachelor (i.e., non-resident). As predicted by the resident-intruder model, resident listeners tended to reply to conspecific males at high rates (≈40 %), while bachelors showed low reply rates (17 %) to resident initiators. Unexpectedly, the lowest-ranking bachelors showed a tendency to reply to the highest-ranking residents. One possible explanation for this counter-intuitive behavior might be that weaker individuals exploit a situation in which it is unremunerated for a stronger opponent to retaliate (i.e., Napoleon strategy) and seize a self-advertisement opportunity in front of a large audience attending to the high-ranking males’ signal. Overall, we show that male Hyraxes employ different counter-singing tactics depending on the residence and rank differences between the participants. This choice of competition tactics can be based on opponents’ individual recognition or/and on direct decoding of opponents’ traits encoded in the song. In nature, conflicts are usually resolved through signaling rather than by actual fighting. Rock Hyrax males often participate in vocal competitions, possibly to reduce the need for physical confrontations. During our study on the dynamics of male Hyrax vocal competition, we discovered that Hyraxes employ mixed counter-singing strategy dependent on the residence status and social rank differences between the participants. A paradoxical “Napoleon-complex” tactic was observed in interactions between males, when low ranking bachelors were found to interact and challenge the highest-ranking residents. On the other hand, residents were found to interact with opponents regardless of residency and/or rank. On top of the cognitive abilities required to individually recognize an opponent and possibly decode its vocal signals, our results suggest that male Hyraxes compare own individual traits to those of the opponent in a mutual signal assessment interaction.
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the energy cost of singing in wild Rock Hyrax males evidence for an index signal
Animal Behaviour, 2013Co-Authors: Amiyaal Ilany, Tchia Ilany, Adi Barocas, Eli GeffenAbstract:In many species individuals advertise their quality via vocal communication. Although sound production requires energy, it is still unclear to what extent vocalizing increases metabolic rate. A substantial energetic cost of vocalization may suggest that it serves as a handicap. In this study, we evaluated the energetic cost of vocalization in the context of other activities in a free-living mammal. In the Rock Hyrax, Procavia capensis, males produce loud complex songs that convey multiple types of information about the singer. We used the doubly labelled water method to estimate field metabolic rate (FMR), in males that were collar-fitted with miniaturized recorders. Higher-ranked males sang longer songs, which also featured higher sound energy. However, contrary to our predictions, the duration of singing was negatively correlated with FMR, whereas the duration of other social sounds, typically associated with social conflicts, had a positive effect on FMR. We suggest that higher-ranking males expend overall less energy due to lower intrinsic metabolism, and thus the singing duration effect on FMR is a reflection of social rank. Rock Hyrax singing is therefore assessed as requiring a high effort over a short period but not as a lengthy activity, matching the category of index signals. Singing may also serve as a handicap to the signaller, not because of its energetic cost but because it exposes the singer to potential predation. Our study is the first to record the activities and vocalizations of a free-living mammal in such detail. We discuss the costs and benefits of Hyrax songs, suggesting that singing males trade safety from predators for increasing their reputation.
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The energy cost of singing in wild Rock Hyrax males: Evidence for an index signal
Animal Behaviour, 2013Co-Authors: Amiyaal Ilany, Tchia Ilany, Adi Barocas, Michael Kam, Eli GeffenAbstract:In many species individuals advertise their quality via vocal communication. Although sound production requires energy, it is still unclear to what extent vocalizing increases metabolic rate. A substantial energetic cost of vocalization may suggest that it serves as a handicap. In this study, we evaluated the energetic cost of vocalization in the context of other activities in a free-living mammal. In the Rock Hyrax, Procavia capensis, males produce loud complex songs that convey multiple types of information about the singer. We used the doubly labelled water method to estimate field metabolic rate (FMR), in males that were collar-fitted with miniaturized recorders. Higher-ranked males sang longer songs, which also featured higher sound energy. However, contrary to our predictions, the duration of singing was negatively correlated with FMR, whereas the duration of other social sounds, typically associated with social conflicts, had a positive effect on FMR. We suggest that higher-ranking males expend overall less energy due to lower intrinsic metabolism, and thus the singing duration effect on FMR is a reflection of social rank. Rock Hyrax singing is therefore assessed as requiring a high effort over a short period but not as a lengthy activity, matching the category of index signals. Singing may also serve as a handicap to the signaller, not because of its energetic cost but because it exposes the singer to potential predation. Our study is the first to record the activities and vocalizations of a free-living mammal in such detail. We discuss the costs and benefits of Hyrax songs, suggesting that singing males trade safety from predators for increasing their reputation. © 2013 The Association for the Study of Animal Behaviour.
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variance in centrality within Rock Hyrax social networks predicts adult longevity
PLOS ONE, 2011Co-Authors: Adi Barocas, Amiyaal Ilany, Lee Koren, Eli GeffenAbstract:BACKGROUND: In communal mammals the levels of social interaction among group members vary considerably. In recent years, biologists have realized that within-group interactions may affect survival of the group members. Several recent studies have demonstrated that the social integration of adult females is positively associated with infant survival, and female longevity is affected by the strength and stability of the individual social bonds. Our aim was to determine the social factors that influence adult longevity in social mammals. METHODOLOGY/PRINCIPAL FINDINGS: As a model system, we studied the social Rock Hyrax (Procavia capensis), a plural breeder with low reproductive skew, whose groups are mainly composed of females. We applied network theory using 11 years of behavioral data to quantify the centrality of individuals within groups, and found adult longevity to be inversely correlated to the variance in centrality. In other words, animals in groups with more equal associations lived longer. Individual centrality was not correlated with longevity, implying that social tension may affect all group members and not only the weakest or less connected ones. CONCLUSIONS/SIGNIFICANCE: Our novel findings support previous studies emphasizing the adaptive value of social associations and the consequences of inequality among adults within social groups. However, contrary to previous studies, we suggest that it is not the number or strength of associations that an adult individual has (i.e. centrality) that is important, but the overall configuration of social relationships within the group (i.e. centrality SD) that is a key factor in influencing longevity.
Paul R Manger - One of the best experts on this subject based on the ideXlab platform.
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sociality affects rem sleep episode duration under controlled laboratory conditions in the Rock Hyrax procavia capensis
Frontiers in Neuroanatomy, 2017Co-Authors: Nadine Gravett, Adhil Bhagwandin, Oleg I Lyamin, Jerome M Siegel, Paul R MangerAbstract:The Rock Hyrax, Procavia capensis, is a highly social, diurnal mammal. In the current study several physiologically measurable parameters of sleep, as well as the accompanying behaviour, were recorded continuously from five Rock Hyraxes, for 72 h under solitary (experimental animal alone in the recording chamber), and social conditions (experimental animal with 1 or 2 additional, non-implanted animals in the recording chamber). The results revealed no significant differences between solitary and social conditions for total sleep times, number of episodes, episode duration or slow wave activity (SWA) for all states examined. The only significant difference observed between social and solitary conditions was the average duration of rapid eye movement (REM) sleep episodes. REM sleep episode duration was on average 20 sec and 40 sec longer under social conditions daily and during the dark period, respectively. It is hypothesized that the increase in REM sleep episode duration under social conditions could possibly be attributed to improved thermoregulation strategies, however considering the limited sample size and design of the current study further investigations are needed to confirm this finding. Whether the conclusions and the observations made in this study can be generalised to all naturally socially sleeping mammals remains an open question.
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nuclear organization of the Rock Hyrax procavia capensis amygdaloid complex
Brain Structure & Function, 2016Co-Authors: Audemarie Limacherburrell, Adhil Bhagwandin, Nadine Gravett, Busisiwe C Maseko, Paul R MangerAbstract:The current study details the nuclear organization of the Rock Hyrax amygdaloid complex using both Nissl and myelin stains, along with a range of immunohistochemical stains. The Rock Hyrax appears to be the least derived of the Afrotherians, a group with a huge range of body phenotypes, life histories and specialized behaviours, brain sizes, and ecological niches. In this sense, the Rock Hyrax represents a species where the organization of the amygdaloid complex may be reflective of that in stem Eutherian mammals. Our analysis indicates that the nuclear organization of the Rock Hyrax amygdaloid complex is indeed very similar to that in other mammals studied, with four major nuclear groupings (the deep or basolateral group; the superficial or cortical-like or corticomedial group; the centromedial group; and the other amygdaloid nuclei) being observed, which is typical of Eutherian mammals. Moreover, each of these groupings is composed of several nuclei, the vast majority of which were readily identified in the Rock Hyrax. Small nuclei identified in rodents and primates were absent in the superficial and centromedial groups, seemingly involved with olfaction. A novel shell-like nucleus of the accessory basal nuclear cluster was observed in the Rock Hyrax, again, likely to be involved in olfaction. The current study underlines the conserved nature of nuclear parcellation in the Eutherian mammal amygdaloid complex and indicates that across most species, the flow of information processing related to species-specific affective-laden stimuli and the resultant physiological and behavioural outcomes are likely to be similar across species.
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the distribution of doublecortin immunopositive cells in the brains of four afrotherian mammals the hottentot golden mole amblysomus hottentotus the Rock Hyrax procavia capensis the eastern Rock sengi elephantulus myurus and the four toed sengi petro
Brain Behavior and Evolution, 2014Co-Authors: Nina Patzke, Nadine Gravett, Nigel C Bennett, Andrea Leroy, Nhlanhla W Ngubane, Katarina Medger, Consolate Kaswerakyamakya, Emmanuel Gilissen, Richard Chawana, Paul R MangerAbstract:Adult neurogenesis in the mammalian brain is now a widely accepted phenomenon, typically occurring in two forebrain structures: the subgranular zone (SGZ) of the hippocampal dentate gyrus and the subventricular zone (SVZ). Until recently, the majority of studies have focused on laboratory rodents, and it is under debate whether the process of adult neurogenesis occurs outside of the SGZ and the SVZ in other mammalian species. In the present study, we investigated potential adult neurogenetic sites in the brains of two elephant shrews/sengis, a golden mole and a Rock Hyrax, all members of the superorder Afrotheria. Doublecortin (DCX) immunoreactivity was used as a proxy to visualise adult neurogenesis, which is expressed in neuronal precursor cells and immature neurons. In all four species, densely packed DCX-positive cells were present in the SVZ, from where cells appear to migrate along the rostral migratory stream towards the olfactory bulb (OB). DCX-immunopositive cells were present in the granular cell layer and the glomerular layer of the OB. In the hippocampus, DCX-immunopositive cells were observed in the SGZ and in the granular layer of the dentate gyrus, with DCX-immunopositive processes extending into the molecular layer. In addition to these well-established adult neurogenic regions, DCX-immunopositive cells were also observed in layer II of the neocortex and the piriform cortex. While the present study reveals a similar pattern of adult neurogenesis to that reported previously in other mammals, further studies are needed to clarify if the cortical DCX-immunopositive cells are newly generated neurons or cells undergoing cortical remodelling.
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sleep in the Rock Hyrax procavia capensis
Brain Behavior and Evolution, 2012Co-Authors: Nadine Gravett, Adhil Bhagwandin, Oleg I Lyamin, Jerome M Siegel, Paul R MangerAbstract:We investigated sleep in theRock Hyrax, Procavia capensis, a social mammal that typically lives in colonies on Rocky outcrops throughout most parts of Southern Africa. The sleep of 5 wild-captured, adult Rock Hyraxes was recorded continuously for 72 h using telemetric relay of signals and allowing unimpeded movement. In addition to waking, slow wave sleep (SWS) and an unambiguous rapid eye movement (REM) state, a sleep state termed somnus innominatus (SI), characterized by low-voltage, high-frequency electroencephalogram, an electromyogram that stayed at the same amplitude as the preceding SWS episode and a mostly regular heart rate, were identified. If SI can be considered a form of low-voltage non-REM, the implication would be that the Rock Hyrax exhibits the lowest amount of REM recorded for any terrestrial mammal studied to date. Conversely, if SI is a form of REM sleep, it would lead to the classification of a novel subdivision of this state; however, further investigation would be required. The Hyraxes spent on average 15.89 h (66.2%) of the time awake, 6.02 h (25.1%) in SWS, 43 min (3%) in SI and 6 min (0.4%) in REM. The unambiguous REM sleep amounts were on average less than 6 min/day. The most common state transition pathway in these animals was found to be wake → SWS → wake. No significant differences were noted with regard to total sleep time, number of episodes and episode duration for all states between the light and dark periods.Thus, prior classification of the Rock Hyrax as strongly diurnal does not appear to hold under controlled laboratory conditions.
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Sleep in the Rock Hyrax, Procavia capensis
Brain Behavior and Evolution, 2012Co-Authors: Nadine Gravett, Adhil Bhagwandin, Oleg I Lyamin, Jerome M Siegel, Paul R MangerAbstract:We investigated sleep in theRock Hyrax, Procavia capensis , a social mammal that typically lives in colonies on Rocky outcrops throughout most parts of Southern Africa. The sleep of
