Variation In Social Organization Research Articles

Spatio-temporal vigilance architecture of an Australian flying-fox colony

The social structure of animal aggregations may vary considerably in both space and time, yet little is known about how this affects vigilance. Here, we investigate the vigilance architecture of a colony of wild-living grey-headed flying-foxes (Pteropus poliocephalus) in Australia and examine how spatial as well as temporal variation in social organization influences social and environmental vigilance. We sampled color-marked individuals at different stages of the reproductive cycle and the year and at different locations in the colony to examine the effects of temporal and spatial factors on social and environmental vigilance. We found that vigilance architecture reflected the social structure of the colony, with the highest environmental vigilance being displayed by bats at the periphery of the colony, and the highest social vigilance by bats that roosted at intermediate distances from the colony’s edge. Furthermore, we found that vigilance levels reflected changes in reproductive state, with social vigilance increasing toward the mating season, particularly in males. Our findings show that spatial and temporal variation in social structure can have differential effects on social and environmental vigilance. This highlights the necessity to differentiate between functions of vigilance to understand fully vigilance architecture in aggregations of social animals.

Convergence in Relation To Level of Societal Development

A classic version of convergence theory was proposed by Marion Levy as part of his theory of modernization: If and as the level of modernization increases (defined as a higher ratio of reliance upon inanimate energy and tools relative to animate energy), the level of structural uniformity among relatively modernized societies continually increases. I test this hypothesis by using the coefficient of variation (V) as the measure of convergence. I analyze a wide range of variables: level of economic development, capitalist market economy, demographic variables, technology, the state and political democracy, cognitive modernization, health, income inequality and poverty, gender particularism–universalism, and information and communications. Each variable is treated as one test of the hypothesis. The hypothesis is first tested by dividing 201 societies into quartiles representing four levels of development as of 1990, and comparing their V scores at one point in time (around the year 2000). Full confirmation of the hypothesis is a monotonic decline in V scores as we move from the least to the most developed societies; this is observed in 19 out of 51, or 37 percent, of the tests. The second set of tests is a stricter, longitudinal test of the hypothesis. Among the 21 societies already developed in 1965, as their level of development continued to rise from 1965 to the present, they became more convergent in 32 out of 45, or 71 percent, of the tests. Thus, variation in social structure is greater among less modernized than among more modernized societies, and this has implications for theories of globalization.

Genome-Wide Expression Patterns and the Genetic Architecture of a Fundamental Social Trait

Explaining how interactions between genes and the environment influence social behavior is a fundamental research goal, yet there is limited relevant information for species exhibiting natural variation in social organization. The fire ant Solenopsis invicta is characterized by a remarkable form of social polymorphism, with the presence of one or several queens per colony and the expression of other phenotypic and behavioral differences being completely associated with allelic variation at a single Mendelian factor marked by the gene Gp-9. Microarray analyses of adult workers revealed that differences in the Gp-9 genotype are associated with the differential expression of an unexpectedly small number of genes, many of which have predicted functions, implying a role in chemical communication relevant to the regulation of colony queen number. Even more surprisingly, worker gene expression profiles are more strongly influenced by indirect effects associated with the Gp-9 genotypic composition within their colony than by the direct effect of their own Gp-9 genotype. This constitutes an unusual example of an “extended phenotype” and suggests a complex genetic architecture with a single Mendelian factor, directly and indirectly influencing the individual behaviors that, in aggregate, produce an emergent colony-level phenotype.

Seasonal variation in social organisation and diurnal activity budget of the Greater Rhea (Rhea americana) in the Argentinean pampas

We analysed seasonal variation in the size and composition of groups, and individual behaviour, of a wild population of Greater Rheas (Rhea americana) in the Argentinean pampas. We performed seasonal censuses over 8 years, and made focal observations on 59 individuals from different groups to assess the proportion of time spent in vigilance, feeding, walking, preening or resting, and noted the number of courtship displays, copulations and aggressive interactions. Rheas were solitary or formed groups of 2–20 individuals. Mean typical group-size (TGS) over the year was 7.61 birds but varied significantly with season, TGS decreasing during the breeding season (spring), possibly owing to formation of harems. TGS of males decreased in spring whereas TGS of females did not vary seasonally. During spring, individuals spent more time vigilant and less time feeding, and were involved in many courtship interactions. Most aggression (72%) was between males and mainly occurred during winter and spring, suggesting strong intrasexual competition. Social organisation and group dynamics appear to be profoundly affected by the mating system of the Greater Rhea.

Molecular variation at a candidate gene implicated in the regulation of fire ant social behavior.

The fire ant Solenopsis invicta and its close relatives display an important social polymorphism involving differences in colony queen number. Colonies are headed by either a single reproductive queen (monogyne form) or multiple queens (polygyne form). This variation in social organization is associated with variation at the gene Gp-9, with monogyne colonies harboring only B-like allelic variants and polygyne colonies always containing b-like variants as well. We describe naturally occurring variation at Gp-9 in fire ants based on 185 full-length sequences, 136 of which were obtained from S. invicta collected over much of its native range. While there is little overall differentiation between most of the numerous alleles observed, a surprising amount is found in the coding regions of the gene, with such substitutions usually causing amino acid replacements. This elevated coding-region variation may result from a lack of negative selection acting to constrain amino acid replacements over much of the protein, different mutation rates or biases in coding and non-coding sequences, negative selection acting with greater strength on non-coding than coding regions, and/or positive selection acting on the protein. Formal selection analyses provide evidence that the latter force played an important role in the basal b-like lineages coincident with the emergence of polygyny. While our data set reveals considerable paraphyly and polyphyly of S. invicta sequences with respect to those of other fire ant species, the b-like alleles of the socially polymorphic species are monophyletic. An expanded analysis of colonies containing alleles of this clade confirmed the invariant link between their presence and expression of polygyny. Finally, our discovery of several unique alleles bearing various combinations of b-like and B-like codons allows us to conclude that no single b-like residue is completely predictive of polygyne behavior and, thus, potentially causally involved in its expression. Rather, all three typical b-like residues appear to be necessary.

Controversy over the application of current socioecological models to folivorous primates: Colobus vellerosus fits the predictions

We explore the applicability of the current socio-ecological model to characterize the social structure of Colobus vellerosus, a folivorous primate. The current socio-ecological model predicts that female social relationships should respond in predictable ways to food abundance and distribution and associated competitive regimes. It appears to successfully explain variation in social structure in some primate species; however, recent research indicates that several folivorous or folivore-frugivorous species seem to be exceptions. We present data on social relationships and social structure in two groups of C. vellerosus over 15 months at Boabeng-Fiema, Ghana. As predicted by the model, our results indicate the co-occurrence of 1) low levels of grooming between female C. vellerosus when compared with other species, 2) an absence of female coalitions over food, and 3) female dispersal. Taken together, these traits suggest a "Dispersal-Egalitarian" species. However, our results also indicate female-female affiliation was higher than male-female affiliation, which was more indicative of a "female resident" species. Our data also suggests inter-sexual affiliation varied among groups. This variation in inter-sexual affiliation could be due to variation in the intensity of infanticidal threats between groups. The combination of these social characteristics lead us to conclude that C. vellerosus' social structure is largely congruent with the ecological indicators of food distribution and female competitive regime that we have previously documented, which indicated high quality foods were not monopolizable or usurpable and behavioral evidence of within-group contest competition (i.e. supplantations over food) was rare. But the combination of higher female-female affiliation (compared to male-female) and female dispersal is difficult to explain in light of predictions, unless future work reveals female residency is more predominant than female dispersal in our population. We also discuss reasons why some folivores do not appear to fit the predictions of the current socio-ecological model.

Primate group size and interpreting socioecological models: Do folivores really play by different rules?

Because primates display such remarkable diversity, they are an ideal taxon within which to examine the evolutionary significance of group living and the ecological factors responsible for variation in social organization. However, as with any social vertebrate, the ecological determinants of primate social variability are not easily identified. Interspecific variation in group size and social organization results from the compromises required to accommodate the associative and dissociative forces of many factors, including predation,1–3 conspecific harassment and infanticide,4–6 foraging competition1, 7 and cooperation,8 dominance interactions,9 reproductive strategies, and socialization.10–12 Causative explanations have emerged primarily through the construction of theoretical models that organize the observed variation in primate social organization and group size relative to measurable ecological variation.

CHANGES IN MATING SYSTEM AND SOCIAL STRUCTURE OF THE ANT PETALOMYRMEX PHYLAX ARE ASSOCIATED WITH RANGE EXPANSION IN CAMEROON

Past climate shifts have led to major oscillations in species distributions. Hence historical contingencies and selective processes occurring during such phases may be determinants for understanding the forces that have shaped extant phenotypes. In the plant-ant Petalomyrmex phylax (Formicinae), we observed spatial variation in number of queens in mature colonies, from several queens (high polygyny) in the median part of its distribution to a moderate number of queens (weak polygyny) or even only a single queen (monogyny) in the southwesternmost populations. This variation did not correlate with indicators of variation in current nest site availability and colony turnover, the supposedly determinant selective forces acting on gyny in ants. We show here that the variation in social structure correlates with a historical process corresponding to a progressive colonization of coastal southern Cameroon by the ant. Using microsatellite markers, we observed a clear pattern of isolation by distance except for the southernmost populations. Measures of genetic variability that do not take into account allele size were at equilibrium in all except the southernmost populations, suggesting recent foundation of the latter. Measures of genetic diversity taking into account allele size showed a clinal north-south decrease in variance of allele size. We propose that southern populations have yet to regain allele size variance after bottlenecks associated with the foundation of new populations, and that this variance is regained over time. Hence variation in social structure mirrors an old but still active southward colonization process or metapopulation dynamics, possibly in association with an expansion of the rain forest habitat during the late Holocene. A low number of queens in ant colonies is typically associated with strong dispersal capacity. We therefore suggest that the initial founders of new populations belong to the monogynous to weakly polygynous phenotype, and that queen number progressively increases in older populations.

A New Test of Convergence Theory

AbstractA classic version of convergence theory was proposed by Marion Levy (1966) as part of his theory of modernization: if and as the level of modernization increases (defined as a higher ratio of reliance upon inanimate energy and tools, relative to animate energy), the level of structural uniformity among relatively modernized societies continually increases. This hypothesis that there is more uniformity among modernized than among non-modernized societies is tested here with cross-national data from 148 non-modernized and 52 modernized societies. Using the coefficient of variation (V) as the measure of convergence, I analyze a wide range of variables: level of economic development, capitalist market economy, demographic variables, technology, the state and political democracy, cognitive modernization, health, income inequality and poverty, gender particularism-universalism, and information and communications. I find that the modernized societies do show more convergence (lower V scores) than the non-modernized societies on 49 of the 51 variables tested. Among the 21 societies that were already modernized in 1965, as they became more modernized during the period from1965 to the present, they also became more convergent on 32 of the 45 variables analyzed. Thus, variation in social structure is greater among less modernized than among more modernized societies, and this has implications for theories of globalization.

Studying the individual within the peer context: Are we on target?

The methodological and theoretical advances in this volume provide new perspectives on longstanding questions about the extent to which both complementarity and reciprocity underlie social relationships. These chapters highlight innovative approaches for clarifying the role of contextual and developmental variations in social structures and processes that are at the core of developmental social network science.

Alternative life-histories in a socially polymorphic ant

Social organisms vary greatly in the number of breeders per group; yet, the causes and consequences of this variation remain poorly known. Here, we show that variation in social structure is tightly linked with changes in several fundamental life-history traits within one population of ants. Multiple-queen colonies of Formica selysi were much more populous than single-queen ones. They also occurred in areas of higher nest density, had longer colony lifespan, produced smaller queens that presumably disperse less, and invested less in reproductive individuals relative to workers. These multiple changes in life histories are consistent with a shift in the mode of colony foundation and the degree of philopatry of queens. They may also provide various fitness benefits to members of multiple-queen colonies and are likely to play a central role in the evolution and maintenance of polymorphic social structures.

BREEDING SYSTEM, COLONY STRUCTURE, AND GENETIC DIFFERENTIATION IN THE CAMPONOTUS FESTINATUS SPECIES COMPLEX OF CARPENTER ANTS

All social insects live in highly organized societies. However, different social insect species display striking variation in social structure. This variation can significantly affect the genetic structure within populations and, consequently, the divergence between species. The purpose of this study was to determine if variation in social structure was associated with species diversification in the Camponotus festinatus desert carpenter ant species complex. We used polymorphic DNA microsatellite markers to dissect the breeding system of these ants and to determine if distinct C. festinatus forms hybridized in their natural range. Our analysis of single-queen colonies established in the laboratory revealed that queens typically mated with only a single male. The genotypes of workers sampled from a field population suggested that multiple, related queens occasionally reproduced within colonies and that colonies inhabited multiple nests. Camponotus festinatus workers derived from colonies of the same form originating at different locales were strongly differentiated, suggesting that gene flow was geographically restricted. Overall, our data indicate that C. festinatus populations are highly structured. Distinct C. festinatus forms possess similar social systems but are genetically isolated. Consequently, our data suggest that diversification in the C. festinatus species complex is not necessarily associated with a shift in social structure.

Molecular Evolutionary Analyses of the Odorant-Binding Protein Gene Gp-9 in Fire Ants and Other Solenopsis Species

The fire ant Solenopsis invicta exists in two social forms, one with colonies headed by a single reproductive queen (monogyne form) and the other with colonies containing multiple queens (polygyne form). This variation in social organization is associated with variation at the gene Gp-9, with monogyne colonies harboring only the B allelic variant and polygyne colonies containing b-like variants as well. We generated new Gp-9 sequences from 15 Solenopsis species and combined these with previously published sequences to conduct a comprehensive, phylogenetically based study of the molecular evolution of this important gene. The exon/intron structure and the respective lengths of the five exons of Gp-9 are identical across all species examined, and we detected no evidence for intragenic recombination. These data conform to a previous suggestion that Gp-9 lies in a genomic region with low recombination, and they indicate that evolution of the coding region in Solenopsis has involved point substitutions only. Our results confirm a link between the presence of b-like alleles and the expression of polygyny in all South American fire ant species known to possess colonies of both social forms. Moreover, phylogenetic analyses show that b-like alleles comprise a derived clade of Gp-9 sequences within the socially polymorphic species, lending further support to the hypothesis that monogyny preceded polygyny in this group of fire ants. Site-specific maximum likelihood tests identified several amino acids that have experienced positive selection, two of which are adjacent to the inferred binding-pocket residues in the GP-9 protein. Four other binding-pocket residues are variable among fire ant species, although selection is not implicated in this variation. Branch-specific tests revealed strong positive selection on the stem lineage of the b-like allele clade, as expected if selection drove the amino acid replacements crucial to the expression of polygyne social organization. Such selection may have operated via the ligand-binding properties of GP-9, as one of the two amino acids uniquely shared by all b-like alleles is predicted to be a binding-pocket residue.

On Hunting and Virilocality

Previous articleNext article No AccessDiscussionOn Hunting and Virilocality1KeithF.OtterbeinKeithF.OtterbeinDepartment of Anthropology, State University of New York at Buffalo, Amherst, NY 14261, U.S.A ([email protected]). 6 viii 04 Search for more articles by this author Department of Anthropology, State University of New York at Buffalo, Amherst, NY 14261, U.S.A ([email protected]). 6 viii 04PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Current Anthropology Volume 46, Number 1February 2005 Sponsored by the Wenner-Gren Foundation for Anthropological Research Article DOIhttps://doi.org/10.1086/427097 Views: 23Total views on this site Citations: 6Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:William P. Mitchell, Conrad P. Kottak Keith F. Otterbein (1936-2015), American Anthropologist 118, no.11 (Feb 2016): 229–231.https://doi.org/10.1111/aman.12499Karen L. Kramer, Russell D. Greaves Postmarital Residence and Bilateral Kin Associations among Hunter-Gatherers, Human Nature 22, no.1-21-2 (Jun 2011): 41–63.https://doi.org/10.1007/s12110-011-9115-7Carol R. Ember What We Know and What We Don’t Know About Variation in Social Organization: Melvin Ember’s Approach to the Study of Kinship, Cross-Cultural Research 45, no.11 (Nov 2010): 16–36.https://doi.org/10.1177/1069397110383947Keith F. Otterbein Clan and Tribal Conflict, (Jan 2008): 660–666.https://doi.org/10.1016/B978-0-12-820195-4.00005-4Keith F. Otterbein Clan and Tribal Conflict, (Jan 2008): 268–275.https://doi.org/10.1016/B978-012373985-8.00025-8 J. Patrick Gray / Andre Costopoulos On Artificial Trends in Comparative Studies using Standard Cross‐Cultural Sample Data: Possibility and Probability Gray, Current Anthropology 47, no.11 (Jul 2015): 149–151.https://doi.org/10.1086/498954

BREEDING SYSTEM, COLONY STRUCTURE, AND GENETIC DIFFERENTIATION IN THE CAMPONOTUS FESTINATUS SPECIES COMPLEX OF CARPENTER ANTS

All social insects live in highly organized societies. However, different social insect species display striking variation in social structure. This variation can significantly affect the genetic structure within populations and, consequently, the divergence between species. The purpose of this study was to determine if variation in social structure was associated with species diversification in the Camponotus festinatus desert carpenter ant species complex. We used polymorphic DNA microsatellite markers to dissect the breeding system of these ants and to determine if distinct C. festinatus forms hybridized in their natural range. Our analysis of single-queen colonies established in the laboratory revealed that queens typically mated with only a single male. The genotypes of workers sampled from a field population suggested that multiple, related queens occasionally reproduced within colonies and that colonies inhabited multiple nests. Camponotus festinatus workers derived from colonies of the same form originating at different locales were strongly differentiated, suggesting that gene flow was geographically restricted. Overall, our data indicate that C. festinatus populations are highly structured. Distinct C. festinatus forms possess similar social systems but are genetically isolated. Consequently, our data suggest that diversification in the C. festinatus species complex is not necessarily associated with a shift in social structure.

INTRASEXUAL TERRITORIALITY IN WOODCHUCKS (MARMOTA MONAX)

Species demonstrating intraspecific variation in social systems can be powerful models for understanding evolution of those systems. As a group, marmots exhibit several types of spacing systems, usually involving some degree of territoriality. Researchers have described populations of 1 species, the woodchuck, Marmota monax, as territorial and as nonterritorial, and such variation has been linked to ecological conditions. I used direct observations of individually recognized animals to describe the spacing system of a high-density population of Marmota monax in southern Maine. This population exhibited intrasexual territoriality. Home range overlap generally was higher between males and females than between same-sex individuals, and woodchucks tended to approach more members of the same sex more quickly compared with members of the opposite sex. Time spent scent marking varied across the active season but did not vary by sex. Males had larger home ranges than females, and home range sizes varied over time, perhaps in response to resources. Amount of overlap also was greater in some years than others, and such changes may be related to kinship. Philopatry and timing of dispersal also vary in this species and have implications for the evolution of sociality.

Variation in mating system and group structure in two populations of swift foxes, Vulpes velox

We studied 26 reproductive groups of swift foxes, Vulpes velox, from both high- and low-density areas during three field seasons in northwestern Texas, U.S.A., to examine whether differences in population density affect mating system and group structure. Although high- and low-density populations were only separated by 40 km and vegetation and diets were similar between sites, polygynous groups, communal denning and nonbreeding females occurred in the area of high density, whereas only monogamous pairs occurred in the area of low density. Annual survival of adult swift foxes was 66% in the area of high density, but 44% in the area of low density. Predation from coyotes, Canis latrans, was the only mortality factor that differed ( P=0.01) between sites and contributed most to differences in survival. Although previous research indicated that variation in social systems among canids is related to bottom–up forces (i.e. food, habitat), the results of our study indicate that variation in social systems can also be related to top–down forces (i.e. predation, displacement by larger competitor).

Speckled warblers break cooperative rules: absence of helping in a group-living member of the Pardalotidae

In the majority of cooperatively breeding bird species, subordinates help the dominant pair to provision the young, regardless of the origin of groups and relatedness between members. Within the family that includes speckled warblers, Chthonicola sagittata, there is considerable variation in social organization and parental behaviour, but the societies of other group-living species in this family are of kin, and subordinates provision the young of breeders. Speckled warblers differ in that offspring are never philopatric, and breeding groups comprise unrelated individuals. We used behavioural observations and DNA fingerprinting to examine genetic parentage and the mating system of the group-living speckled warbler in Canberra, Australia. Speckled warblers breed as pairs or in trios consisting of a female with two males. Alpha males are socially dominant to beta males and maintain dominance through aggression. Beta males never helped to feed nestlings or fledglings, even though they competed for copulations and in one case gained paternity of two of three young in a brood. The social system is therefore polyandrous but not cooperative. As well as competing for copulations with females on their own territories, beta males and single males (those that had lost their breeding partner) regularly undertook extraterritorial forays, most often when the neighbouring female was fertile. Failure by beta males to help even with broods containing their own offspring may be adaptive in this species and may result from increased opportunity for extrapair fertilizations or enhancement of prospects for future reproduction through the formation of alliances with females.

Adult male emigration and a female-based social organization in swift foxes, Vulpes velox

Members of the family Canidae are distinguished from other carnivore families by pair bonding and male care of the young. Because of the importance of food provisioning and territorial defence by males, social structure among canids is shared or even dominated by males. However, small, insectivorous species of canids show little male parental care, although whether social structure differs from other canids is unknown. We combined data from three independent research projects on a small canid, the swift fox, to help elucidate the social organization of this species. Based on data on movements of 35 adult mated pairs and the fate of litters, we found that adult females maintained territories and family structure, whereas adult males tended to emigrate. This is the first evidence of a female-based social organization among any canid species. This type of social organization probably resulted from the decreased importance of territorial defence and food provisioning by males, as their diet is primarily insectivorous during summer when young are weaned. Our results, along with others, indicate that variations in social structure among canid species are strongly influenced by the importance of food provisioning and territorial defence by males.

VARIABLE QUEEN NUMBER IN ANT COLONIES: NO IMPACT ON QUEEN TURNOVER, INBREEDING, AND POPULATION GENETIC DIFFERENTIATION IN THE ANT FORMICA SELYSI

Variation in queen number alters the genetic structure of social insect colonies, which in turn affects patterns of kin-selected conflict and cooperation. Theory suggests that shifts from single- to multiple-queen colonies are often associated with other changes in the breeding system, such as higher queen turnover, more local mating, and restricted dispersal. These changes may restrict gene flow between the two types of colonies and it has been suggested that this might ultimately lead to sympatric speciation. We performed a detailed microsatellite analysis of a large population of the ant Formica selysi, which revealed extensive variation in social structure, with 71 colonies headed by a single queen and 41 by multiple queens. This polymorphism in social structure appeared stable over time, since little change in the number of queens per colony was detected over a five-year period. Apart from queen number, single- and multiple-queen colonies had very similar breeding systems. Queen turnover was absent or very low in both types of colonies. Single- and multiple-queen colonies exhibited very small but significant levels of inbreeding, which indicates a slight deviation from random mating at a local scale and suggests that a small proportion of queens mate with related males. For both types of colonies, there was very little genetic structuring above the level of the nest, with no sign of isolation by distance. These similarities in the breeding systems were associated with a complete lack of genetic differentiation between single- and multiple-queen colonies, which provides no support for the hypothesis that change in queen number leads to restricted gene flow between social forms. Overall, this study suggests that the higher rates of queen turnover, local mating, and population structuring that are often associated with multiple-queen colonies do not appear when single- and multiple-queen colonies still coexist within the same population, but build up over time in populations consisting mostly of multiple-queen colonies.