1
|
Pietrangeli E, Saldaña-Sánchez AA, Spaan D, Aureli F. Let's not use it! A dynamic no-use zone between the home ranges of two spider monkey groups. Primates 2024; 65:173-181. [PMID: 38436838 DOI: 10.1007/s10329-024-01119-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 01/21/2024] [Indexed: 03/05/2024]
Abstract
It is common that neighboring groups of the same species use some of the same areas, resulting in home-range overlap. Areas between the home ranges of neighboring groups not used by either group (no-use zone or NUZ) are rarely reported. Here, we report the existence of a NUZ between the home ranges of two Geoffroy's spider monkey groups, and examine its spatial changes over time and the ecological and behavioral underpinnings of such phenomenon. Although its size and location changed between 2017 and 2022, the NUZ was always present. We did not find any differences in the vegetation structure and composition between the NUZ and the ranging areas and in the monkeys' activity patterns between areas adjacent to the NUZ and the other parts of the ranging areas. The number of monkey vocalizations was lower and subgroup size was smaller (although the number of males did not differ) in areas adjacent to the NUZ than in the other parts of the ranging areas. Both changes possibly reflect the tendency to conceal their presence to the neighboring group. Our findings contribute to the understanding of primate space use and highlight the need to focus on the areas delimiting home ranges.
Collapse
Affiliation(s)
- Edoardo Pietrangeli
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Mexico.
- ConMonoMaya A.C, Chemax, Mexico.
| | | | - Denise Spaan
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Mexico.
- ConMonoMaya A.C, Chemax, Mexico.
| | - Filippo Aureli
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Mexico
- ConMonoMaya A.C, Chemax, Mexico
- Research Centre in Evolutionary Anthropology and Palaeoecology, Liverpool John Moores University, Liverpool, UK
| |
Collapse
|
2
|
Pavez-Fox MA, Siracusa ER, Ellis S, Kimock CM, Rivera-Barreto N, Negron-Del Valle JE, Phillips D, Ruiz-Lambides A, Snyder-Mackler N, Higham JP, Brent LJ, De Moor D. Socioecological drivers of injuries in female and male rhesus macaques ( Macaca mulatta). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.20.563310. [PMID: 38559204 PMCID: PMC10979908 DOI: 10.1101/2023.10.20.563310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Competition over access to resources, such as food and mates, is believed to be one of the major costs associated with group living. Two socioecological factors suggested to predict the intensity of competition are group size and the relative abundance of sexually active individuals. However, empirical evidence linking these factors to injuries and survival costs is scarce. Here, we leveraged 10 years of data from free-ranging rhesus macaques where injuries inflicted by conspecifics are associated with a high mortality risk. We tested if group size and adult sex ratio predicted the occurrence of injuries and used data on physical aggression to contextualise these results. We found that males were less likely to be injured when living in larger groups, potentially due to advantages in intergroup encounters. Females, instead, had higher injury risk when living in larger groups but this was not explained by within-group aggression among females. Further, male-biased sex ratios predicted a weak increase in injury risk in females and were positively related to male-female aggression, indicating that male coercion during mating competition may be a cause of injuries in females. Overall, our results provide insights into sex differences in the fitness-related costs of competition and empirical evidence for long-standing predictions on the evolution of group living.
Collapse
Affiliation(s)
- Melissa A. Pavez-Fox
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom EX4 4QG
- Department of Psychology and Neuroscience, University of St Andrews, United Kingdom KY16 9JP
| | - Erin R. Siracusa
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom EX4 4QG
| | - Samuel Ellis
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom EX4 4QG
| | - Clare M. Kimock
- Department of Anthropology, New York University, New York, NY 10003
- Department of Psychology, Nottingham Trent University, Nottingham, United Kingdom NG1 4FQ
| | - Nahiri Rivera-Barreto
- Caribbean Primate Research Center, University of Puerto Rico, San Juan, Puerto Rico 00936-5067
| | | | - Daniel Phillips
- Center for Evolution and Medicine, Arizona State University, Temple, AZ 85281, United States
| | - Angelina Ruiz-Lambides
- Caribbean Primate Research Center, University of Puerto Rico, San Juan, Puerto Rico 00936-5067
| | - Noah Snyder-Mackler
- Center for Evolution and Medicine, Arizona State University, Temple, AZ 85281, United States
- School of Life Sciences, Arizona State University, Temple, AZ 85281
- School for Human Evolution and Social Change, Arizona State University, Temple, AZ 85281
| | - James P. Higham
- Department of Anthropology, New York University, New York, NY 10003
| | - Lauren J.N. Brent
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom EX4 4QG
| | - Delphine De Moor
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, United Kingdom EX4 4QG
| |
Collapse
|
3
|
Gussone L, García de la Chica A, Fernandez-Duque E. Intergroup encounters in pair-living primates: Comparative analysis and a case study of pair-living and monogamous owl monkeys (Aotus azarae) of Argentina. Am J Primatol 2024; 86:e23572. [PMID: 37919869 DOI: 10.1002/ajp.23572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/28/2023] [Accepted: 10/20/2023] [Indexed: 11/04/2023]
Abstract
The function of intergroup encounters (IGEs) may differ substantially among species of different group sizes and social organizations. Research in group-living primates has shown that the behavioral responses during IGEs can vary widely from affiliative to neutral or aggressive interactions; still, little is known about IGEs in pair-living taxa. We conducted a systematic literature review to find relevant studies on the functions of IGEs in pair-living nonhuman primates that could inform analyses of IGE data (n = 242 IGEs, 21 groups and 10 solitary individuals, 1997-2020) from wild owl monkeys, a pair-living, monogamous primate with extensive biparental care. We identified 1315 studies published between 1965 and 2021; only 13 of them (n = 10 species) contained raw data on the number of IGEs. Our review of those studies showed that IGEs are common, but highly variable in their nature and characteristics in pair-living primates. To examine the non-mutually exclusive hypotheses of resource-, and mate defense, and infanticide avoidance we analyzed data from the Owl Monkey Project 27-year long database to build first an a priori model set. To incorporate prior knowledge from the literature review, we conducted our analyses as a consecutive series of binomial logistic regressions. All IGEs including all biologically relevant parameters (N = 156) were codified into three different behavioral categories (Reaction, Agonism, and Physical Aggression). The analysis showed that owl monkeys regularly engaged in IGEs, most of which were agonistic. They showed more reaction when infants were present, but reactions were less physically aggressive when infants and pregnant females were involved. Overall, our results lend more support for the infant and mate defense hypotheses than they do for the resource defense one.
Collapse
Affiliation(s)
- Leonie Gussone
- Institute for Evolutionary Biology and Ecology, Bonn University, Bonn, Germany
- Department of Anthropology, University of Minnesota, Twin-Cities, Minnesota, USA
| | - Alba García de la Chica
- Instituto de Ecología, Genética y Evolución, Universidad de Buenos Aires, Buenos Aires, Argentina
- Owl Monkey Project-Fundación ECO, Formosa, Argentina
| | - Eduardo Fernandez-Duque
- Owl Monkey Project-Fundación ECO, Formosa, Argentina
- Department of Anthropology and School of the Environment, Yale University, New Haven, Connecticut, USA
- Facultad de Recursos Naturales, Universidad Nacional de Formosa, Formosa, Argentina
| |
Collapse
|
4
|
Lousa TC, Mendes FDC. Disputes over provisioned resources are no more intense between groups than within groups in free-ranging Sapajus libidinosus. Primates 2024; 65:61-68. [PMID: 37938471 DOI: 10.1007/s10329-023-01105-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 10/27/2023] [Indexed: 11/09/2023]
Abstract
Socioecological models predict that disputes between primate groups will be more intense than those within groups, given that the systematic loss of contests over a given resource will restrict the access of all of the members of that group to that resource. Higher levels of aggression are also expected for provisioned resources that have a more lucrative cost:benefit ratio. The levels of aggression in and between two free-ranging tufted capuchin monkey (Sapajus libidinosus) groups in the context of daily provisioning with bananas were evaluated. The aim of a complementary analysis was to identify possible predictors of the frequency of disputes at the site of the provisioned resource. The disputes were recorded using all-events sampling, while the social behaviour of the study groups was recorded by instantaneous scan sampling. The data were analysed using t-test, Mann-Whitney's U, and generalised linear modelling. Between-group disputes were no more intense than within-group events, and did not involve more individuals, or more adult females. The frequency of disputes increased as the number of individuals eating bananas increased. No evidence was found that disputes between groups were any more intense than those within groups. Dominance patterns may have affected these findings, by mediating intergroup disputes. An increase in the number of competitors affected the frequency of disputes at the site of the provisioned resource.
Collapse
Affiliation(s)
- Túlio Costa Lousa
- Department of Basic Psychological Processes, Institute of Psychology, University of Brasília, Brasília, DF, 70910-900, Brazil.
| | - Francisco D C Mendes
- Department of Basic Psychological Processes, Institute of Psychology, University of Brasília, Brasília, DF, 70910-900, Brazil
| |
Collapse
|
5
|
Smith JE, Jaeggi AV, Holmes RK, Silk JB. Sex differences in cooperative coalitions: a mammalian perspective. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210426. [PMID: 36440559 PMCID: PMC9703251 DOI: 10.1098/rstb.2021.0426] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 08/09/2022] [Indexed: 11/29/2022] Open
Abstract
In group-living species, cooperative tactics can offset asymmetries in resource-holding potential between individuals and alter the outcome of intragroup conflicts. Differences in the kinds of competitive pressures that males and females face might influence the benefits they gain from forming intragroup coalitions. We predicted that there would be a female bias in intragroup coalitions because females (1) are more like to live with kin than males are, and (2) compete over resources that are more readily shared than resources males compete over. We tested this main prediction using information about coalition formation across mammalian species and phylogenetic comparative analyses. We found that for nearly all species in which intragroup coalitions occur, members of both sexes participate, making this the typical mammalian pattern. The presence and frequency of female or male coalitions were not strongly associated with key socio-ecological factors like resource defensibility, sexual dimorphism or philopatry. This suggests that once the ability to form intragroup coalitions emerges in one sex, it is likely to emerge in the other sex as well and that there is no strong phylogenetic legacy of sex differences in this form of cooperation. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.
Collapse
Affiliation(s)
- Jennifer E. Smith
- Biology Department, University of Wisconsin Eau Claire, 105 Garfield Avenue, Eau Claire, WI 54702, USA
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Adrian V. Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich 8057, Switzerland
| | - Rose K. Holmes
- Biology Department, University of Wisconsin Eau Claire, 105 Garfield Avenue, Eau Claire, WI 54702, USA
| | - Joan B. Silk
- School of Human Evolution and Social Change, Institute of Human Origins, Arizona State University, Tempe, AZ 85287-2402, USA
| |
Collapse
|
6
|
McGuire KM, Sauther ML. Characterizing group and individual engagement in intergroup encounters between small groups of ring-tailed lemurs (Lemur catta) on St. Catherines Island, USA. Primates 2023; 64:161-176. [PMID: 36418748 DOI: 10.1007/s10329-022-01036-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 11/02/2022] [Indexed: 11/25/2022]
Abstract
Primate species exhibit considerable variation in behavior and outcomes during intergroup encounters (IGEs). Social group characteristics, like group size, and individual traits, such as sex, rank, and reproductive status, within those groups can influence both IGE engagement and outcomes. To better understand the impact of group heterogeneity on IGEs, we must examine individual strategies to elucidate individual costs and benefits of engaging in these interactions. Here, we present a descriptive study of the IGEs between two small social groups of ring-tailed lemurs (Lemur catta) on St. Catherines Island, GA, USA. We distinguish between dyadic and multiple-individual interactions between groups to compare collective and individual agonistic engagement. All encounters occurred when the East Road group (N = 7 individuals) traveled from the center of their home range to the boundary with Windmill group's (N = 5 individuals) home range, indicating that East Road might have been actively testing this boundary for access to food resources, sleeping trees, and mating opportunities. We also found notable individual variation in participation during IGEs. The daughters of the highest-ranking females were the most-engaged in dyadic intergroup and intragroup aggression, had high "win" rates during intergroup dyadic encounters, and engaged in intergroup multiple-individual interactions at high levels. These findings indicate that they might value their home range more as "potential alphas" compared to other group members. Dominant females were the most engaged in multiple-individual interactions, suggesting that they contribute heavily to collective action that might result in a gain or loss of access to resources. Finally, these two small groups might be equally matched despite the two-individual group size disparity due to individual free-riding strategies. Future research should focus on individual strategies during IGEs to characterize the complex decisions and trade-offs that influence participation.
Collapse
Affiliation(s)
- Kathleen M McGuire
- Department of Anthropology, University of Colorado Boulder, Boulder, CO, 80302, USA.
| | - Michelle L Sauther
- Department of Anthropology, University of Colorado Boulder, Boulder, CO, 80302, USA
| |
Collapse
|
7
|
McCormick SK, Laubach ZM, Strauss ED, Montgomery TM, Holekamp KE. Evaluating drivers of female dominance in the spotted hyena. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.934659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
IntroductionDominance relationships in which females dominate males are rare among mammals. Mechanistic hypotheses explaining the occurrence of female dominance suggest that females dominate males because (1) they are intrinsically more aggressive or less submissive than males, and/or (2) they have access to more social support than males.MethodsHere, we examine the determinants of female dominance across ontogenetic development in spotted hyenas (Crocuta crocuta) using 30 years of detailed behavioral observations from the Mara Hyena Project to evaluate these two hypotheses.ResultsAmong adult hyenas, we find that females spontaneously aggress at higher rates than males, whereas males spontaneously submit at higher rates than females. Once an aggressive interaction has been initiated, adult females are more likely than immigrant males to elicit submission from members of the opposite sex, and both adult natal and immigrant males are more likely than adult females to offer submission in response to an aggressive act. We also find that adult male aggressors are more likely to receive social support than are adult female aggressors, and that both adult natal and immigrant males are 2–3 times more likely to receive support when attacking a female than when attacking another male. Across all age classes, females are more likely than males to be targets of aggressive acts that occur with support. Further, receiving social support does slightly help immigrant males elicit submission from adult females compared to immigrant males acting alone, and it also helps females elicit submission from other females. However, adult females can dominate immigrant males with or without support far more often than immigrant males can dominate females, even when the immigrants are supported against females.DiscussionOverall, we find evidence for both mechanisms hypothesized to mediate female dominance in this species: (1) male and female hyenas clearly differ in their aggressive and submissive tendencies, and (2) realized social support plays an important role in shaping dominance relationships within a clan. Nevertheless, our results suggest that social support alone cannot explain sex-biased dominance in spotted hyenas. Although realized social support can certainly influence fight outcomes among females, adult females can easily dominate immigrant males without any support at all.
Collapse
|
8
|
Fighting force and experience combine to determine contest success in a warlike mammal. Proc Natl Acad Sci U S A 2022; 119:e2119176119. [PMID: 35700363 PMCID: PMC9231503 DOI: 10.1073/pnas.2119176119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Intergroup conflict has been proposed as a major influence in social evolution. Understanding how intergroup contests exert selection on group living requires determining what properties of groups and their members drive contest success. We analyzed 19 y of data on intergroup fighting in wild banded mongooses to disentangle the factors that determine victory. Two factors, the number of males in the group and the age of the oldest “senior” male, most strongly influence the probability of victory. Senior males may be a benefit because of their disproportionate fighting experience. As in human societies, strength in numbers and the presence of key individuals are critical for success in violent intergroup contests, perhaps influencing selection on individual life history and social behavior. Conflicts between social groups or “intergroup contests” are proposed to play a major role in the evolution of cooperation and social organization in humans and some nonhuman animal societies. In humans, success in warfare and other collective conflicts depends on both fighting group size and the presence and actions of key individuals, such as leaders or talismanic warriors. Understanding the determinants of intergroup contest success in other warlike animals may help to reveal the role of these contests in social evolution. Using 19 y of data on intergroup encounters in a particularly violent social mammal, the banded mongoose (Mungos mungo), we show that two factors, the number of adult males and the age of the oldest male (the “senior” male), have the strongest impacts on the probability of group victory. The advantage conferred by senior males appears to stem from their fighting experience. However, the galvanizing effect of senior males declines as they grow old until, at very advanced ages, senior males become a liability rather than an asset and can be evicted. As in human conflict, strength in numbers and the experience of key individuals combine to determine intergroup contest success in this animal society. We discuss how selection arising from intergroup contests may explain a suite of features of individual life history and social organization, including male eviction, sex-assortative alloparental care, and adult sex ratio.
Collapse
|
9
|
Smith JE, Fichtel C, Holmes RK, Kappeler PM, van Vugt M, Jaeggi AV. Sex bias in intergroup conflict and collective movements among social mammals: male warriors and female guides. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210142. [PMID: 35369756 DOI: 10.1098/rstb.2021.0142] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Intergroup conflict is a major evolutionary force shaping animal and human societies. Males and females should, on average, experience different costs and benefits for participating in collective action. Specifically, among mammals, male fitness is generally limited by access to mates whereas females are limited by access to food and safety. Here we analyse sex biases among 72 species of group-living mammals in two contexts: intergroup conflict and collective movements. Our comparative phylogenetic analyses show that the modal mammalian pattern is male-biased participation in intergroup conflict and female-biased leadership in collective movements. However, the probability of male-biased participation in intergroup conflicts decreased and female-biased participation increased with female-biased leadership in movements. Thus, female-biased participation in intergroup conflict only emerged in species with female-biased leadership in collective movements, such as in spotted hyenas and some lemurs. Sex differences are probably attributable to costs and benefits of participating in collective movements (e.g. towards food, water, safety) and intergroup conflict (e.g. access to mates or resources, risk of injury). Our comparative review offers new insights into the factors shaping sex bias in leadership across social mammals and is consistent with the 'male warrior hypothesis' which posits evolved sex differences in human intergroup psychology. This article is part of the theme issue 'Intergroup conflict across taxa'.
Collapse
Affiliation(s)
- Jennifer E Smith
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Claudia Fichtel
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
| | - Rose K Holmes
- Biology Department, Mills College, 5000 MacArthur Boulevard, Oakland, CA 94631, USA
| | - Peter M Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany.,Department Anthropology/Sociobiology, University of Göttingen, Göttingen, Germany
| | - Mark van Vugt
- Department of Experimental and Applied Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Adrian V Jaeggi
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland
| |
Collapse
|
10
|
De Dreu CKW, Triki Z. Intergroup conflict: origins, dynamics and consequences across taxa. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210134. [PMID: 35369751 PMCID: PMC8977662 DOI: 10.1098/rstb.2021.0134] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although uniquely destructive and wasteful, intergroup conflict and warfare are not confined to humans. They are seen across a range of group-living species, from social insects, fishes and birds to mammals, including nonhuman primates. With its unique collection of theory, research and review contributions from biology, anthropology and economics, this theme issue provides novel insights into intergroup conflict across taxa. Here, we introduce and organize this theme issue on the origins and consequences of intergroup conflict. We provide a coherent framework by modelling intergroup conflicts as multi-level games of strategy in which individuals within groups cooperate to compete with (individuals in) other groups for scarce resources, such as territory, food, mating opportunities, power and influence. Within this framework, we identify cross-species mechanisms and consequences of (participating in) intergroup conflict. We conclude by highlighting crosscutting innovations in the study of intergroup conflict set forth by individual contributions. These include, among others, insights on how within-group heterogeneities and leadership relate to group conflict, how intergroup conflict shapes social organization and how climate change and environmental degradation transition intergroup relations from peaceful coexistence to violent conflict. This article is part of the theme issue ‘Intergroup conflict across taxa’.
Collapse
Affiliation(s)
- Carsten K W De Dreu
- Institute of Psychology, Leiden University, Leiden, The Netherlands.,Center for Research in Experimental Economics and Political Decision Making, University of Amsterdam, Amsterdam, The Netherlands
| | - Zegni Triki
- Department of Zoology, Stockholm University, Stockholm, Sweden
| |
Collapse
|
11
|
García MG, de Guinea M, Bshary R, van de Waal E. Drivers and outcomes of between-group conflict in vervet monkeys. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210145. [PMID: 35369750 PMCID: PMC8977665 DOI: 10.1098/rstb.2021.0145] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neighbouring groups compete over access to resources and territories in between-group encounters, which can escalate into between-group conflicts (BGCs). Both the ecological characteristics of a territory and the rival's fighting ability shape the occurrence and outcome of such contests. What remains poorly understood, however, is how seasonal variability in the ecological value of a territory together with fighting ability related to the likelihood of between-group encounters and the extent to which these escalate into conflicts. To test this, we observed and followed four vervet monkey groups in the wild, and recorded the group structure (i.e. size, composition), the locations and the outcomes of 515 BGCs. We then assessed key ecological measures at these locations, such as vegetation availability (estimated from Copernicus Sentinel 2 satellite images) and the intensity of usage of these locations. We tested to what extent these factors together influenced the occurrence and outcomes of BGCs. We found that the occurrence of BGCs increased at locations with higher vegetation availability relative to the annual vegetation availability within the group's home territory. Also, groups engaging in a BGC at locations far away from their home territory were less likely to win a BGC. Regarding group structure, we found that smaller groups systematically won BGCs against larger groups, which can be explained by potentially higher rates of individual free-riding occurring in larger groups. This study sheds light on how the ecology of encounter locations in combination with a group's social characteristics can critically impact the dynamics of BGCs in a non-human primate species. This article is part of the theme issue ‘Intergroup conflict across taxa’.
Collapse
Affiliation(s)
- Miguel Gareta García
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal 3115, South Africa.,Department of Eco-Ethology, Faculty of Biology, University of Neuchâtel, Rue Emile Argand 11, Neuchâtel 2000, Switzerland
| | - Miguel de Guinea
- Movement Ecology Laboratory, Alexander Silverman Institute of Life Sciences, Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Redouan Bshary
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal 3115, South Africa.,Department of Eco-Ethology, Faculty of Biology, University of Neuchâtel, Rue Emile Argand 11, Neuchâtel 2000, Switzerland
| | - Erica van de Waal
- Inkawu Vervet Project, Mawana Game Reserve, KwaZulu Natal 3115, South Africa.,Department of Ecology and Evolution, Faculty of Biology and Medicine, University of Lausanne, Lausanne 1015, Switzerland
| |
Collapse
|
12
|
Moscovice LR, Hohmann G, Trumble BC, Fruth B, Jaeggi AV. Dominance or Tolerance? Causes and consequences of a period of increased intercommunity encounters among bonobos (Pan paniscus) at LuiKotale. INT J PRIMATOL 2022. [DOI: 10.1007/s10764-022-00286-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractGroup-living primates exhibit variable reactions to intergroup encounters (or IGEs), reflecting species-specific strategies and individual motivations. In chimpanzees (Pan troglodytes), dominating in IGEs provides fitness benefits. Less is known about responses to IGEs in bonobos (Pan paniscus) despite their equal relevance for understanding the origins of human intergroup relations. We observed the Bompusa West (WBp) bonobo community at LuiKotale during a 2-month shift in ranging resulting in frequent IGEs with the smaller Bompusa East (EBp) community. We tested whether incursions provided ecological benefits, and whether responses to IGEs were consistent with inter-community dominance or tolerance. We measured fruit availability and collected activity scans from 26 mature WBp community members when in their core ranging area, during incursions into the EBp ranging area, and during IGEs. We collected data on sexual interactions and aggression with in-group and out-group members during 19 independent IGEs. During their shift in ranging, fruit availability was greater in the EBp ranging area, and WBp bonobos consumed more fruit during incursions than when in their core ranging area. Coalitionary intergroup aggression occurred during nine IGEs, and outcomes were consistent with imbalances in fighting power, in that larger WBp parties supplanted smaller EBp parties from the immediate area. However, communities reformed associations following 70% of coalitionary conflicts, and prolonged IGEs facilitated out-group sexual interactions and female transfers. The WBp community shift in ranging was likely motivated by ecological factors and responses to increased IGEs reflected a mixture of competitive and tolerant strategies.
Collapse
|
13
|
Lousa TC, Mendes FDC. Inter-group conflicts involving adult female and male bearded capuchins, Sapajus libidinosus (Primates: Cebidae), in the context of provisioned resources: resource defense or sexual selection? ZOOLOGIA 2022. [DOI: 10.1590/s1984-4689.v39.e21020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
14
|
Feder JA, Beehner JC, Baniel A, Bergman TJ, Snyder-Mackler N, Lu A. OUP accepted manuscript. Behav Ecol 2022; 33:654-664. [PMID: 35600996 PMCID: PMC9113362 DOI: 10.1093/beheco/arac028] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 01/10/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
Female reproductive maturation is a critical life-history milestone, initiating an individual's reproductive career. Studies in social mammals have often focused on how variables related to nutrition influence maturation age in females. However, parallel investigations have identified conspicuous male-mediated effects in which female maturation is sensitive to the presence and relatedness of males. Here, we evaluated whether the more "classic" socioecological variables (i.e., maternal rank, group size) predict maturation age in wild geladas-a primate species with known male-mediated effects on maturation and a grassy diet that is not expected to generate intense female competition. Females delayed maturation in the presence of their fathers and quickly matured when unrelated, dominant males arrived. Controlling for these male effects, however, higher-ranking daughters matured at earlier ages than lower-ranking daughters, suggesting an effect of within-group contest competition. However, contrary to predictions related to within-group scramble competition, females matured earliest in larger groups. We attribute this result to either: 1) a shift to "faster" development in response to the high infant mortality risk posed by larger groups; or 2) accelerated maturation triggered by brief, unobserved male visits. While earlier ages at maturation were indeed associated with earlier ages at first birth, these benefits were occasionally offset by male takeovers, which can delay successful reproduction via spontaneous abortion. In sum, rank-related effects on reproduction can still occur even when socioecological theory would predict otherwise, and males (and the risks they pose) may prompt female maturation even outside of successful takeovers.
Collapse
Affiliation(s)
- Jacob A Feder
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Circle Rd, Stony Brook, NY, USA
- Address Correspondence to J. A. Feder. E-mail: ; A. Lu. E-mail:
| | - Jacinta C Beehner
- Department of Anthropology, University of Michigan, S. University Ave, Ann Arbor, MI, USA
- Department of Psychology, University of Michigan, Church St, Ann Arbor, MI, USA
| | - Alice Baniel
- School of Life Sciences, Arizona State University, E. Tyler Mall, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, E. Tyler Mall, Tempe, AZ, USA
| | - Thore J Bergman
- Department of Psychology, University of Michigan, Church St, Ann Arbor, MI, USA
- Department of Ecology and Evolutionary Biology, University of Michigan, N. University Ave, Ann Arbor, MI, USA
| | - Noah Snyder-Mackler
- School of Life Sciences, Arizona State University, E. Tyler Mall, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, E. Tyler Mall, Tempe, AZ, USA
- School of Human Evolution and Social Change, Arizona State University, S. Cady Mall, Tempe, AZ, USA
| | - Amy Lu
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Circle Rd, Stony Brook, NY, USA
- Department of Anthropology, Stony Brook University, Circle Rd, Stony Brook, NY, USA
| |
Collapse
|
15
|
|
16
|
Smith JE, von Rueden CR, van Vugt M, Fichtel C, Kappeler PM. An Evolutionary Explanation for the Female Leadership Paradox. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.676805] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Social influence is distributed unequally between males and females in many mammalian societies. In human societies, gender inequality is particularly evident in access to leadership positions. Understanding why women historically and cross-culturally have tended to be under-represented as leaders within human groups and organizations represents a paradox because we lack evidence that women leaders consistently perform worse than men. We also know that women exercise overt influence in collective group-decisions within small-scale human societies, and that female leadership is pervasive in particular contexts across non-human mammalian societies. Here, we offer a transdisciplinary perspective on this female leadership paradox. Synthesis of social science and biological literatures suggests that females and males, on average, differ in why and how they compete for access to political leadership in mixed-gender groups. These differences are influenced by sexual selection and are moderated by socioecological variation across development and, particularly in human societies, by culturally transmitted norms and institutions. The interplay of these forces contributes to the emergence of female leaders within and across species. Furthermore, females may regularly exercise influence on group decisions in less conspicuous ways and different domains than males, and these underappreciated forms of leadership require more study. We offer a comprehensive framework for studying inequality between females and males in access to leadership positions, and we discuss the implications of this approach for understanding the female leadership paradox and for redressing gender inequality in leadership in humans.
Collapse
|
17
|
Group-level cooperation in chimpanzees is shaped by strong social ties. Nat Commun 2021; 12:539. [PMID: 33483482 PMCID: PMC7822919 DOI: 10.1038/s41467-020-20709-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 12/07/2020] [Indexed: 01/30/2023] Open
Abstract
Humans maintain extensive social ties of varying preferences, providing a range of opportunities for beneficial cooperative exchange that may promote collective action and our unique capacity for large-scale cooperation. Similarly, non-human animals maintain differentiated social relationships that promote dyadic cooperative exchange, but their link to cooperative collective action is little known. Here, we investigate the influence of social relationship properties on male and female chimpanzee participations in a costly form of group action, intergroup encounters. We find that intergroup encounter participation increases with a greater number of other participants as well as when participants are maternal kin or social bond partners, and that these effects are independent from one another and from the likelihood to associate with certain partners. Together, strong social relationships between kin and non-kin facilitate group-level cooperation in one of our closest living relatives, suggesting that social bonds may be integral to the evolution of cooperation in our own species.
Collapse
|
18
|
Green PA, Briffa M, Cant MA. Assessment during Intergroup Contests. Trends Ecol Evol 2020; 36:139-150. [PMID: 33187729 DOI: 10.1016/j.tree.2020.09.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 12/11/2022]
Abstract
Research on how competitors assess (i.e., gather information on) fighting ability and contested resources, as well as how assessment impacts on contest processes and outcomes, has been fundamental to the field of dyadic (one-on-one) contests. Despite recent growth in studies of contests between social-living groups, there is limited understanding of assessment during these intergroup contests. We adapt current knowledge of dyadic contest assessment to the intergroup case, describing what traits of groups, group members, and resources are assessed, and how assessment is manifested in contest processes (e.g., behaviors) and outcomes. This synthesis helps to explain the role of individual heterogeneity in assessment and how groups are shaped by the selective pressure of contests.
Collapse
Affiliation(s)
- P A Green
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9FE, UK.
| | - M Briffa
- School of Biological and Marine Sciences, Plymouth University, Drake Circus, Plymouth PL3 8AA, UK
| | - M A Cant
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9FE, UK
| |
Collapse
|
19
|
Fighting for what it’s worth: participation and outcome of inter-group encounters in a pair-living primate, the Javan gibbon (Hylobates moloch). Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02879-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
20
|
Lewis RJ, Sandel AA, Hilty S, Barnett SE. The Collective Action Problem but Not Numerical Superiority Explains Success in Intergroup Encounters in Verreaux’s Sifaka (Propithecus verreauxi): Implications for Individual Participation and Free-Riding. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00155-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
21
|
Van Belle S, Grueter CC, Furuichi T. Dynamics of Intergroup Relationships in Primates: Introduction to the Special Issue. INT J PRIMATOL 2020. [DOI: 10.1007/s10764-020-00159-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
22
|
Samuni L, Mielke A, Preis A, Crockford C, Wittig RM. Intergroup Competition Enhances Chimpanzee (Pan troglodytes verus) In-group Cohesion. INT J PRIMATOL 2019. [DOI: 10.1007/s10764-019-00112-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractIn-group cohesion is an essential component of successful intergroup competition in both human and nonhuman animals, likely facilitating group members access to potential benefits. However, when benefits are equally shared among group members, group defense becomes a collective action problem, which might subvert cohesive participation during intergroup competition. There is a lack of consensus across studies and species with regard to the link between in-group cohesion and intergroup competition, likely as a result of species differences in managing the collective action problem. Here, we examine this link in a species with a striking example of collective action during intergroup competition, chimpanzees (Pan troglodytes verus). Using two years of focal-follow data on males and females in two groups at the Taï Forest, Côte d’Ivoire, we investigated the immediate and long-term effects of intergroup competition (border patrols and intergroup encounters) on measures of in-group cohesion, namely modularity, party size, and intergroup aggression. We found that groups’ association patterns were less modular (more cohesive) in months in which they engaged in more border patrols and intergroup encounters. We found that current and greater prior engagement in intergroup competition predicted larger party sizes. Furthermore, current, but not prior engagement in intergroup competition, predicted reduced intragroup aggression by males but not by females. Increased in-group cohesion in chimpanzees likely reduces potential costs of intergroup competition engagement, by facilitating joint participation in current and future intergroup conflicts, overcoming the collective action problem.
Collapse
|