Intergroup Associations Research Articles

Testing the information centre hypothesis in a multilevel society.

In various animal species conspecifics aggregate at sleeping sites. Such aggregations can act as information centres where individuals acquire up-to-date knowledge about their environment. In some species, communal sleeping sites comprise individuals from multiple groups, where each group maintains stable membership over time. We used GPS tracking to simultaneously record group movement in a population of wild vulturine guineafowl (Acryllium vulturinum) to investigate whether communal sleeping sites can facilitate the transfer of information among individuals across distinct groups. These birds live in large and stable groups that move both together and apart, often forming communal roosts containing up to five groups. We first test whether roosts provide the opportunity for individuals to acquire information from members of other groups by examining the spatial organization at roosts. The GPS data reveal that groups intermix, thereby providing an opportunity for individuals to acquire out-group information. We next conduct a field experiment to test whether naïve groups can locate novel food patches when co-roosting with knowledgeable groups. We find that co-roosting substantially increases the chances for the members of a naïve group to discover a patch known to individuals from other groups at the shared roost. Further, we find that the discovery of food patches by naïve groups subsequently shapes their space use and inter-group associations. We also draw on our long-term tracking to provide examples that demonstrate natural cases where communal roosting has preceded large-scale multi-group collective movements that extend into areas beyond the groups' normal ranges. Our findings support the extension of the information centre hypothesis to communal sleeping sites that consist of distinct social groups.

Canonical correlations between morphoagronomic and production traits in traditional cowpea varieties based on genotypic values

Obtaining information about the main morphoagronomic and yield components, as well as their interrelationships, is of utmost importance in cowpea breeding programs, aiming at the selection of superior genotypes. The analysis of canonical correlations allows us to predict and describe the relationship between groups of characters, allowing the indirect selection of superior genotypes. The objective of this work was to verify relationships between morphological characters and production components through the analysis of canonical correlations using genotypic values obtained via mixed REML/BLUP models in traditional cowpea varieties. The experiment was conducted in a randomized block design with three replications and 12 treatments. Traditional varieties were characterized and evaluated during the germination, seedling, flowering and harvest stages with data obtained from plants, pods and seeds. Using the genotypic correlation matrix, two sets of characteristics were established, Group I, formed by production components and Group II, formed by morphoagronomic characters. A second correlation analysis was performed to verify associations between morphoagronomic and seed traits (seed length, width and thickness). It was found that dependence between the groups evaluated and intergroup associations can be established, which allows the study of cause-effect and the practice of indirect selection between groups of variables studied. An increase in pod length, hundred-grain mass and seed size is achieved through the selection of early maturing plants, with greater width of the apical leaflet and length of the hypocotyl.

Preventing Communal Violence in Myanmar: Power and Legitimacy in Local Conflict Prevention

Violence between Buddhists and Muslims in Myanmar again reached international attention in 2017 when the newly elected democratic government failed to protect Rohingya Muslims from persecution. While inter-group violence is endemic, however, there are clear and strong examples of peaceful co-existence. This article draws on interview and ethnographic evidence from a case of prevented violence in Mingalar Taung Nyunt, Yangon, in 2017, to argue that engaging with the local, complex, and dynamic process of communal violence prevention can enrich contemporary theories of communal violence. The article draws specifically on insights from the theories of political manipulation and civic engagement to argue that the most effective analysis of communal violence will focus on the power dynamics that shape local responses to escalating threat. In Mingalar Taung Nyunt, violence was prevented through the concerted effort of individuals in unique positions that provided them with the legitimacy and political power that allowed them to successfully de-escalate tensions. The article contributes to the understanding of communal violence by emphasising how the role and importance of inter-group associations, government bodies, and others is shaped by the laws and norms of the community in which violence is escalating. The article’s conclusions furthermore outline how the recent military coup in the country will destabilise local peace-keeping efforts in central Myanmar and how such institutions may be rebuilt.

Variation in aggression rates and urinary cortisol levels indicates intergroup competition in wild bonobos

Intergroup competition is a widespread phenomenon across taxa and groups typically compete over access to limited resources, such as food and mates. Such competition may be quantified by changes in individuals' behavioral and physiological status in response to intergroup encounters (IGEs). Bonobos, one of our closest living relatives, are often regarded as xenophilic and exhibit high tolerance towards out-group individuals. This tolerance between groups may still be accompanied by intergroup competition over resources. We hereby compared variation in aggression rates and urinary cortisol levels of bonobos during and outside contexts of IGEs in the Kokolopori Bonobo Reserve and investigated whether food and mate availability influenced males' and females' aggression and cortisol levels, when controlling for dominance rank and the number of individuals present. We found that although females had higher aggression rates and urinary cortisol levels during than outside contexts of IGEs, these increases were not related to food availability or changes in between-group dynamics when maximally tumescent females were present, rather than absent. Furthermore, males showed higher aggression rates and urinary cortisol levels during than outside contexts of IGEs. However, males' responses during IGEs were not related to the presence of maximally tumescent females and food availability. Taken together, while competition intensified during seemingly tolerant IGEs in bonobos, such competition was unrelated to short-term changes in food and mate availability. Despite physical and physiological costs of aggression, bonobos associate with out-group individuals frequently and for extended periods. This suggests potential benefits of bonobo intergroup associations.

Better together? How intergroup associations affect energy balance and feeding behavior in wild bonobos

When the benefits of interacting with out-group members exceed the associated costs, social groups may be expected to be tolerant towards each other. However, in many species exhibiting intergroup tolerance, the nature of benefits gained from intergroup encounters remains unclear. We investigated the potential costs and benefits associated with intergroup associations in bonobos, a species with varying degrees of intergroup tolerance, by testing whether these associations conferred energetic benefits to participants under different socioecological contexts and whether the consequences of these associations substantially differed from within-group competition. We used measures of socioecological factors (fruit abundance and group size), feeding and ranging behaviors, and a physiological marker of energy balance (urinary c-peptide of insulin) collected over a 19-month period from two neighboring wild communities in the Kokolopori Bonobo Reserve, Democratic Republic of the Congo. We found that intergroup associations were not related to individuals’ energy balance, but they were related to variations in individuals’ ranging and feeding behavior. Specifically, bonobos traveled longer distances, visited larger fruit patches, and increased the time spent feeding on fruits on days they associated with the neighboring group. These adaptations in feeding behavior may be strategies to offset the energetic costs of increased travel distances. In the absence of obvious energetic benefits and with clear strategies employed to offset energetic costs, it is likely that intergroup associations in bonobos provide benefits unrelated to energy acquisition, such as social benefits. Our study sheds light on the potential incentives promoting social networks to extend beyond and across groups in a tolerant species.Significance statementIntergroup encounters can be energetically costly due to increased competition over resources. Yet, some species associate with out-group individuals for extended periods of time when the benefits of participating in these associations exceed the potential costs. Bonobos, a species exhibiting intergroup tolerance, modified their feeding behavior during intergroup associations by feeding on larger fruit patches and increasing their time spent feeding on fruits, likely to offset energetic costs of increased travel distances. As results, individuals’ energy balance was not related with intergroup associations. The employment of such strategies in addition to the absence of clear energetic benefits suggests that intergroup associations in bonobos provide social rather than ecological benefits.

Inter-group aggressive interaction patterns indicate male mate defense and female cooperation across bonobo groups at Wamba, Democratic Republic of the Congo.

Although conflicts between groups over valuable resources are common in the animal kingdom, an individual's strategy toward out-group individuals may differ according to the benefits and costs received from inter-group interactions. Groups of bonobos encounter each other frequently and may mingle and range together from a few hours to a few days. During these inter-group associations, individuals across groups exhibit both aggressive and affiliative interactions. This study aimed to examine the strategies that bonobos employ with other groups, by comparing the patterns of within- and inter-group aggression. We observed the aggressive interactions within a group of wild bonobos and between the group and three neighboring groups in Wamba, Luo Scientific Reserve, DR Congo. Bonobos increased the level of cooperation to attack out-group individuals more than they do to attack within-group individuals. Additionally, they reduced the aggression between within-group members during inter-group associations, compared to that when not associated with other groups. Males selectively and cooperatively attacked out-group males. Inter-group aggression among females was rare. Furthermore, females sometimes formed coalitions with out-group individuals to attack a common target. Our results support the hypothesis that inter-group competition occurs in bonobos, with males across groups competing over mates. Females across groups were tolerant and even cooperative with each other. Regardless of the ideal male strategy, female tolerant and cooperative relationships across groups and female within-group superiority over males could preserve tolerant inter-group relationships in bonobos.

Canonical correlations between agronomic traits and seed physiological quality in segregating soybean populations.

The objective of this study was to evaluate the relationship between agronomic traits and physiological traits of seeds in segregating soybean populations by canonical correlation analysis. Seven populations and two commercial cultivars in three generations were used: F3 plants and F4 seeds; F4 plants and F5 seeds, and F4 seeds and plants. The following agronomic traits (group I) were evaluated: number of days to maturity, plant height at maturity, insertion height of first pod, number of pods, grain yield, and oil content. The physiological quality of seeds (group II) was evaluated using germination, accelerated aging, emergence, and emergence rate index tests. The results showed that agronomic traits and physiological traits of seeds are not independent. Intergroup associations were established by the first canonical pair for the generation of F3 plants and F4 seeds, especially between more productive plants with a larger pod number and high oil content and seeds with a high germination percentage and emergence rate. For the generation of F4 plants and F5 seeds, the first canonical pair indicated an association between reduced maturity cycle, seeds with a high emergence percentage and a high percentage of normal seedlings after accelerated aging. According to the second canonical pair, more productive and taller plants were associated with seed vigor. For the generation of F4 seeds and plants, the associations established by the first canonical pair occurred between seed vigor and more productive plants with high oil content and reduced maturity cycle, and those established by the second canonical pair between seeds of high physiological quality and tall plants.

Relationships between Primary and Secondary Yield Components of a Maize Population after 13 Stratified Mass Selection Cycles

This research aimed to identify the relationships between the primary and secondary components of the maize yield using the techniques of canonical correlation and factors analysis. The base population was composed of nine randomized crossing hybrids in an isolated field, in the years 2006-2012. Canonical correlations were estimated between the variable group consisting of primary (GI) and secondary (GII) yield components. To Factor Analysis (FA), we chose a number of common factors equal to the number of eigen values higher than the existing unit in the phenotypic correlations matrix of variables and the orthogonal factor model was opted. Primary and secondary yield components of maize grains are not independent. Inter-group associations are established by plants with higher height, stem diameter, dry weight and lower ear height, which positively influence primary yield components (dry ear weight, ear length and hundred-grain weight). Factor analysis allowed to reduce a large number of original variables observed to a small number of abstract variables and can be used to complement the canonical variables technique.

Sympatric woodland Myotis bats form tight-knit social groups with exclusive roost home ranges.

BackgroundThe structuring of wild animal populations can influence population dynamics, disease spread, and information transfer. Social network analysis potentially offers insights into these processes but is rarely, if ever, used to investigate more than one species in a community. We therefore compared the social, temporal and spatial networks of sympatric Myotis bats (M. nattereri (Natterer's bats) and M. daubentonii (Daubenton's bats)), and asked: (1) are there long-lasting social associations within species? (2) do the ranges occupied by roosting social groups overlap within or between species? (3) are M. daubentonii bachelor colonies excluded from roosting in areas used by maternity groups?ResultsUsing data on 490 ringed M. nattereri and 978 M. daubentonii from 379 colonies, we found that both species formed stable social groups encompassing multiple colonies. M. nattereri formed 11 mixed-sex social groups with few (4.3%) inter-group associations. Approximately half of all M. nattereri were associated with the same individuals when recaptured, with many associations being long-term (>100 days). In contrast, M. daubentonii were sexually segregated; only a quarter of pairs were associated at recapture after a few days, and inter-sex associations were not long-lasting. Social groups of M. nattereri and female M. daubentonii had small roost home ranges (mean 0.2 km2 in each case). Intra-specific overlap was low, but inter-specific overlap was high, suggesting territoriality within but not between species. M. daubentonii bachelor colonies did not appear to be excluded from roosting areas used by females.ConclusionsOur data suggest marked species- and sex-specific patterns of disease and information transmission are likely between bats of the same genus despite sharing a common habitat. The clear partitioning of the woodland amongst social groups, and their apparent reliance on small patches of habitat for roosting, means that localised woodland management may be more important to bat conservation than previously recognised.

Modernization, Structural Characteristics, and Societal Rates of Crime: An Application of Blau's Macrosociological Theory

The objectives of this article are to examine the relationships between several structural characteristics associated with modernity and the ratio of property crimes to homicides, and to develop a theoretical interpretation for such relationships. The proposed interpretation involves an application of Blau's general macrosociological theory. Blau's (1977) theory is concerned with the determinants of intergroup associations. The key to applying his theory to the phenomenon of crime lies in the conceptualization of property crimes as characteristically intergroup interactions, and homicides as ingroup interactions. Blau's theorems concerning the structural determinants of rates of intergroup associations in general can then be extended to account for the relative frequency of these two types of crime. Several specific hypotheses are derived from Blau's theory and are tested with cross-national data. The results are for the most part in accord with theoretical expectations. Moreover, the proposed interpretation for the relationship between modern social structures and the ratio of property crimes to homicides is more consistent with the full pattern of results than are some plausible alternative interpretations.

A Macrosociological Theory of Social Structure

Social structure is conceptualized as the distributions of a population among social positions in a multidimensional space of positions. This quantitative conception of social structure is the basis for a deductive theory of the macrostructure of social associations in society. The likelihood that people engage in intergroup associations under specifiable structural conditions can bededuced from analaytic propositions about structural properties without any assumption about sociopsychological dispositions to establish intergroup associations, indeed, on the assumption that people prefer ingroup relations. Group size governs the probability of intergroup relations, a fact that has paradoxical implications for discrimination by a majority against a minority. Inequality impedes and heterogeneity promotes intergroup relations. The major structural condition that governs intergroup relations is the degree of connection of parameters. Intersecting parameters exert structural constraints to participate in interg...