A multi-level society comprised of one-male and multi-male core units in an African colobine (<i>Colobus angolensis ruwenzorii</i>)

Stead, Samantha M.; Teichroeb, Julie A.

doi:10.1101/641746

Cited by 3 publications

(16 citation statements)

References 76 publications

(125 reference statements)

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“…In contrast, other black‐and‐white colobus typically show group sizes around 10–15 individuals (Fashing, 2011). In C. angolensis ruwenzorii , we have observed male dispersal ( N = 9 males) to only occur within the band between core units and female dispersal to mostly occur to core units outside the band ( N = 3/4 (75%); Stead & Teichroeb, 2019; unpublished data).…”

Section: Methodsmentioning

confidence: 72%

“…C. angolensis (weight range: males, 7.6–12.6 kg; females, 6.4–9.2 kg; Mittermeier, Rylands, Wilson, & Nash, 2013) is relatively widespread from Angola in the west to Kenya and Tanzania in the east but the seven subspecies show discontinuous distributions. The subspecies we studied, Rwenzori Angolan colobus (AKA Adolf Friedrich's colobus, C. angolensis ruwenzorii ) is an outlier within its clade forming extremely large group sizes (300–500 individuals in montane areas; Fimbel, Vedder, Dierenfeld, & Mulindahabi, 2001; Miller et al, 2018) and the only multilevel societies identified in an African colobine species (Stead & Teichroeb, 2019). In contrast, other black‐and‐white colobus typically show group sizes around 10–15 individuals (Fashing, 2011).…”

Section: Methodsmentioning

confidence: 99%

“…Our study band (TR) ranged over a forested area of approximately 1.5 km 2 and was organized into 12 cohesive core units, consisting of seven MMUs and five OMUs. These core units fission and fuse into (typically to ~ 20 m) and out of proximity with one another throughout the day, however core units usually remain spatially distinct (Stead & Teichroeb, 2019). We collected data on 11 of the 12 core units in TR band (six MMUs and five OMUs).…”

Section: Methodsmentioning

confidence: 99%

“…Adult male C. angolensis ruwenzorii also use penile displays frequently, where the pink, erect penis against the black body hair appears to extend this white line in the AGD region (Figure 1a). This subspecies forms extremely large groups (up to 500 individuals in montane areas, Miller, Uwingeneye, Kaplin, Judge, & Grueter, 2018) and the fission‐fusion of social units can be frequent (Stead & Teichroeb, 2019). This is exactly the type of social organization that may favor the evolution of “badges of status” (Rohwer, 1982), which are defined as ornaments or signals that relate stable information about sender quality (Bergman & Sheehan, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…We have recently confirmed that the large groups formed by C. angolensis ruwenzorii are a unique multilevel society in the non‐human primates. Cohesive core units that can be unimale/multifemale (i.e., a “one‐male unit” [OMU]) or multimale/multifemale (i.e., a “multi‐male unit” [MMU]) aggregate into at least three tiers of social organization—“core units” share a range in a “band” and show preferential patterns of association among one another, which we term “clans” (Stead & Teichroeb, 2019). It is the presence of many MMUs with socially integrated, reproductive males that make this social organization unique in primates.…”

Section: Introductionmentioning

confidence: 99%

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Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus

Teichroeb

Stead

Edwards

et al. 2020

American J Primatol

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Anogenital distance (AGD) is positively correlated to fetal androgen exposure and developmental masculinization in mammals. Independent of overall body size, AGD shows a strong positive correlation with male fertility and in rodents, AGD is a good indicator of male competitive ability and is associated with female choice. We hypothesized that AGD will also predict male competitive ability in non‐human primates. To test this, we measured AGD noninvasively with a parallel laser in a wild population of Angolan colobus monkeys (Colobus angolensis ruwenzorii) in Uganda and correlated to it to their social structure. C. angolensis ruwenzorii form a multilevel society with both one‐male/multifemale units (OMUs) and multimale/multifemale units (MMUs). We compared AGD in males from five OMUs and six MMUs and related it to their fecal androgen metabolite concentrations, dominance rank and body size, and to the number of females in their unit. Males in OMUs had greater access to females, so were predicted to have longer AGDs, but this was not found. AGD also did not correlate overall with mean fecal androgen metabolites in MMUs. However, AGD was correlated with dominance rank in MMUs, demonstrating that higher‐ranking males in these multimale units had longer AGDs. Body size did not show the same relationship with dominance rank, suggesting that male rank was not just a reflection of absolute male size. Our findings indicate that AGD predicts male competitive ability in this species and that it may be a useful correlate throughout the non‐human primates. These results also support the idea that prenatal androgen exposure increases the likelihood of the expression of behaviors that maintain high dominance rank.

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Section: Methodsmentioning

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus

Teichroeb

Stead

Edwards

et al. 2020

American J Primatol

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Spatiotemporal association patterns in a supergroup of Rwenzori black‐and‐white colobus (Colobus angolensis ruwenzorii) are consistent with a multilevel society

Miller

Uddin

Judge

et al. 2020

American J Primatol

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Primates display broad diversity in their social organization. The social groups of a few primate species are organized in a multilevel fashion, with large groups composed of multiple, core one-male units (OMUs). A characteristic of multilevel societies is that the higher levels can include hundreds of individuals. The Rwenzori black-and-white colobus (Colobus angolensis ruwenzorii) in the montane forests of Rwanda form supergroups and have been suspected to exhibit multilevel social organization. Here we present the first data on the "anatomy" of a supergroup numbering 500+ individuals. We identified subgroups within the supergroup based on progression data, extracting the social network structure from the time-stamped spatiotemporal distribution of passing individuals identified to age-sex class, and selecting an optimal time window for each network using the two-step approach developed by Uddin, Choudhury, Farhad, and Rahman (2017). We detail the existence of core units-multi-male units (MMUs) with a mean of 1.7 adult males and 3.1 adult females, as well as OMUs, all-female units and bachelor units composed of adult and sub-adult males. More than two-thirds of units are MMUs. These grouping patterns conform to a multilevel society with predominantly multi-male core units, a social system that has recently also been described for a population of the same taxon in Uganda. Individual identification will be required to corroborate these interpretations. K E Y W O R D SColobus angolensis ruwenzorii, longitudinal social networks, multilevel societies, multi-male units, primates, Rwanda, social network analysis, spatiotemporal data streams

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Flexibility in the social structure of male chimpanzees (Pan troglodytes schweinfurthii) in the Budongo Forest, Uganda

Badihi

Bodden

Zuberbühler

et al. 2021

Preprint

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Individuals of social species face a trade-off between the competitive costs and social benefits of group living. Species show a range of social strategies to deal with this trade-off, for example atomistic fission-fusion dynamics in which temporary social groups of varying size and membership form and re-form; or molecular fission-fusion dynamics which contain stable sets of multilevel nested subgroups. Chimpanzees are considered an archetypical atomistic fission-fusion species, using dynamic changes in day-to-day association to moderate the costs of within-group competition. It has been argued that humans’ highly flexible social organisation allows us to live in extremely large groups. Using four years of association data from two neighbouring communities of East African chimpanzees (Pan troglodytes schweinfurthii), we describe new levels of flexibility in chimpanzee social organisation and confirm the presence of subgrouping in a second, large community of chimpanzees. We show that males from the larger Waibira community (N males 24-31) exhibited additional levels of semi-stable subgrouping, while males from the smaller Sonso community (N males 10-13) did not. Subgroup membership showed stability across some years, but flexibility across others. Our data support the hypothesis that chimpanzees can incorporate strategies other than fission-fusion to overcome costs of social living, and that their social organisation may be closer to that of modern humans than previously described.SIGNIFICANCE STATEMENTSocial living offers benefits and costs; groups can more easily locate and defend resources, but experience increased individual competition. Many species, or individuals, flexibly adjust their social organization when faced with different competitive pressures. It is argued that humans are unique among primates in combining multigroup social organisation with fission-fusion dynamics flexibly within and across groups, and that doing so allows us to live in extremely large groups. Using four-years of association data we show new levels of flexibility in chimpanzee social organization. Males from a typically-sized community employed atomistic fission-fusion dynamics, but males in an unusually large community incorporated additional semi-stable levels of subgrouping. Our data support the hypothesis that chimpanzee males combine social organization strategies, and that doing so may allow them, like humans, to mitigate individual costs at larger community sizes.

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A multi-level society comprised of one-male and multi-male core units in an African colobine (Colobus angolensis ruwenzorii)

Cited by 3 publications

References 76 publications

Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus

Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus

Spatiotemporal association patterns in a supergroup of Rwenzori black‐and‐white colobus (Colobus angolensis ruwenzorii) are consistent with a multilevel society

Flexibility in the social structure of male chimpanzees (Pan troglodytes schweinfurthii) in the Budongo Forest, Uganda

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