Within-group feeding competition and socioecological factors influencing social organization of gorillas in the Kahuzi-Biega National Park, Democratic Republic of Congo

Yamagiwa, Juichi; Basabose, Kanyunyi; Kaleme, Kiswele; Yumoto, Takakazu

doi:10.1017/cbo9780511542558.015

Cited by 15 publications

(20 citation statements)

References 86 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although multi-male groups were rare in WLG, most of the subgrouping occurred in multi-male groups during the fruiting season (Goldsmith 1996;Remis 1997). Although no evidence of subgrouping was found in polygynous groups of ELG at Itebero, frequent subgrouping occurred in an ELG multi-male group during the fruiting season at Kahuzi (Yamagiwa et al 2003). These results suggest that a frugivorous diet may facilitate subgrouping in multi-male groups of WLGs and ELGs.…”

Section: Group Size and Compositionmentioning

confidence: 62%

See 1 more Smart Citation

Intra-specific variation in social organization of gorillas: implications for their social evolution

Yamagiwa

Kahekwa

Basabose³

2003

Primates

Self Cite

135

102

View full text Add to dashboard Cite

We analysed intra-specific variation in the social organization of gorillas and ecological and social factors influencing them, based on recent data on diet, day journey length, home range size, group size and proportion of multi-male groups in three subspecies [western lowland gorillas (WLG); eastern lowland gorillas (ELG); mountain gorillas (MG)]. Median group size was similar across subspecies and across habitats, but the extraordinarily large group including >30 gorillas was only found in habitat with dense terrestrial herbaceous vegetation. Within-group competition may determine the upper limit of group size in frugivorous WLGs and ELGs in lowland habitats with scarce undergrowth. A frugivorous diet may be a causal factor of subgrouping in multi-male groups of WLGs and ELGs, while a folivorous diet may prevent subgrouping in multi-male groups of MGs. Social factors, rather than ecological factors, may play an important role in the formation of multi-male groups and their cohesiveness in MGs. High gregariousness of female gorillas and their prolonged association with a protector male are explained by their vulnerability to both infanticide (MGs) and predators (ELGs). Comparison of long-term changes in group composition and individual movements between ELGs in Kahuzi and MGs in the Virungas suggest that the occurrence of infanticide may promote kin-male association within a group. Threat of infanticide may stimulate MG females to transfer into multi-male groups to seek reliable protection and maturing MG males to stay in their natal groups after maturity. By contrast, the absence of infanticide may facilitate ELG females to associate with infants and other females at transfer and ELG males to establish large groups in a short period by taking females from their natal groups, by luring females from neighbouring groups, or by takeover of a widow group after the death of its leading male. These conditions may prevent ELG and WLG maturing males from remaining to reproduce in their natal groups and possibly result in a rare occurrence of multi-male groups in their habitats. Similar reproductive features of MG and ELG females suggest both female strategies have been adaptive in their evolutionary history.

show abstract

Section: Group Size and Compositionmentioning

confidence: 62%

“…Tree density and species diversity in the Itebero region were about 3 times higher than those in the Kahuzi region (Yamagiwa et al 2003).…”

Section: Study Areamentioning

confidence: 74%

Intra-specific variation in social organization of gorillas: implications for their social evolution

Yamagiwa

Kahekwa

Basabose³

2003

Primates

Self Cite

135

102

View full text Add to dashboard Cite

show abstract

“…Western lowland gorillas commonly live in polygynous groups with a single silverback (Bradley, Doran-Sheehy, & Vigilant, 2007;Doran & McNeilage, 1998 Nadler, Herndon, & Wallis, 1986;Robbins, 2007;Robbins et al, 2004;Watts, 2012;Yamagiwa, Basabose, Kaleme, & Yumoto, 2003). While all females are submissive to the silverback, they also exercise considerable mate choice and may freely disperse to a new silverback during intergroup encounters.…”

Section: Allostatic Load During Growth a N D De V E L O P Me N Tmentioning

confidence: 99%

Allostatic load and biological anthropology

Edes

Crews

2017

American J Phys Anthropol

View full text Add to dashboard Cite

Multiple stressors affect developing and adult organisms, thereby partly structuring their phenotypes. Determining how stressors influence health, well-being, and longevity in human and nonhuman primate populations are major foci within biological anthropology. Although much effort has been devoted to examining responses to multiple environmental and sociocultural stressors, no holistic metric to measure stress-related physiological dysfunction has been widely applied within biological anthropology. Researchers from disciplines outside anthropology are using allostatic load indices (ALIs) to estimate such dysregulation and examine life-long outcomes of stressor exposures, including morbidity and mortality. Following allostasis theory, allostatic load represents accumulated physiological and somatic damage secondary to stressors and senescent processes experienced over the lifespan. ALIs estimate this wear-and-tear using a composite of biomarkers representing neuroendocrine, cardiovascular, metabolic, and immune systems. Across samples, ALIs are associated significantly with multiple individual characteristics (e.g., age, sex, education, DNA variation) of interest within biological anthropology. They also predict future outcomes, including aspects of life history variation (e.g., survival, lifespan), mental and physical health, morbidity and mortality, and likely health disparities between groups, by stressor exposures, ethnicity, occupations, and degree of departure from local indigenous life ways and integration into external and commodified ones. ALIs also may be applied to similar stress-related research areas among nonhuman primates. Given the reports from multiple research endeavors, here we propose ALIs may be useful for assessing stressors, stress responses, and stress-related dysfunction, current and long-term cognitive function, health and well-being, and risk of early mortality across many research programs within biological anthropology. K E Y W O R D Saging, allostasis, frailty, growth and development, nonhuman primates, senescence, stress | I N T R O D U C T I O NTraditional research foci within biological anthropology include variations in stress, morbidity, and mortality (for reviews, see Ice & James, 2007;Little, 2010). Despite this long-term focus, the field continues to pursue a reliable, relatively easy to apply metric for assessing lifetime stress and stress-related outcomes. We suggest incorporating the theory of allostasis and methods for assessing allostatic load within anthropological theory and methodology to aid in closing this gap. As a theory, allostasis was developed to explain how mammalian physiological responses to stressors in their environments evolved to maximize the probability of survival while limiting somatic damage (Korte, Koolhaas, Wingfield, & McEwen, 2005;McEwen & Stellar, 1993;McEwen & Wingfield, 2003;Sterling, 2004Sterling, , 2012Sterling & Eyer, 1988). Unfortunately, such beneficial defensive responses come at a cost and, over time, repeated allostatic activi...

show abstract

“…Males disperse on reaching adulthood, and may either wander alone or join an all-male bachelor group, some of which persist for years. While 97% of breeding groups contain only one adult male (Harcourt & Stewart, 2007), among mountain gorillas sons remain in their natal group 40% of the time, in which case they mate only with females bonded to them, and their father does the same (Fossey, 1984;Watts, 1991;Robbins, 2001;Yamagiwa et al 2003). Both father and son defend the social group.…”

Section: Gorillasmentioning

confidence: 99%

Why are there apes? Evidence for the co‐evolution of ape and monkey ecomorphology

Hunt

2016

Journal of Anatomy

View full text Add to dashboard Cite

Apes, members of the superfamily Hominoidea, possess a distinctive suite of anatomical and behavioral characters which appear to have evolved relatively late and relatively independently. The timing of paleontological events, extant cercopithecine and hominoid ecomorphology and other evidence suggests that many distinctive ape features evolved to facilitate harvesting ripe fruits among compliant terminal branches in tree edges. Precarious, unpredictably oriented, compliant supports in the canopy periphery require apes to maneuver using suspensory and non-sterotypical postures (i.e. postures with eccentric limb orientations or extreme joint excursions). Diet differences among extant species, extant species numbers and evidence of cercopithecoid diversification and expansion, in concert with a reciprocal decrease in hominoid species, suggest intense competition between monkeys and apes over the last 20 Ma. It may be that larger body masses allow great apes to succeed in contest competitions for highly desired food items, while the ability of monkeys to digest antifeedant-rich unripe fruits allows them to win scramble competitions. Evolutionary trends in morphology and inferred ecology suggest that as monkeys evolved to harvest fruit ever earlier in the fruiting cycle they broadened their niche to encompass first more fibrous, tannin-and toxin-rich unripe fruits and later, for some lineages, mature leaves. Early depletion of unripe fruit in the central core of the tree canopy by monkeys leaves a hollow sphere of ripening fruits, displacing antifeedant-intolerant, later-arriving apes to small-diameter, compliant terminal branches. Hylobatids, orangutans, Pan species, gorillas and the New World atelines may have each evolved suspensory behavior independently in response to local competition from an expanding population of monkeys. Genetic evidence of rapid evolution among chimpanzees suggests that adaptations to suspensory behavior, vertical climbing, knuckle-walking, consumption of terrestrial piths and intercommunity violence had not yet evolved or were still being refined when panins (chimpanzees and bonobos) and hominins diverged.

show abstract

Within-group feeding competition and socioecological factors influencing social organization of gorillas in the Kahuzi-Biega National Park, Democratic Republic of Congo

Cited by 15 publications

References 86 publications

Intra-specific variation in social organization of gorillas: implications for their social evolution

Intra-specific variation in social organization of gorillas: implications for their social evolution

Allostatic load and biological anthropology

Why are there apes? Evidence for the co‐evolution of ape and monkey ecomorphology

Contact Info

Product

Resources

About