Socioecological influences on the reproductive success of female mountain gorillas (Gorilla beringei beringei)

Robbins, Martha M.; Robbins, Andrew M.; Gerald-Steklis, Netzin; Steklis, Horst D.

doi:10.1007/s00265-006-0321-y

Cited by 83 publications

(85 citation statements)

References 81 publications

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“…In combination with previous census data and analyses of female reproductive success (Kalpers et al 2003;Robbins et al 2007), this study has provided additional evidence that the second folivore paradox applies to mountain gorillas in the Virunga Volcano Region. Females were not more significantly likely to emigrate from larger groups, and the immigration rate was not significantly greater into smaller groups.…”

Section: Discussionmentioning

confidence: 77%

“…Infant mortality has been nearly twice as high in one-male groups, a significant difference that is at least partly due to infanticide (Fossey 1984;Watts 1989;Robbins et al 2007). For example, infanticide typically occurs when the silverback dies in one-male groups but not when the dominant male dies in multimale groups (ibid).…”

Section: Introductionmentioning

confidence: 99%

“…If the costs of dispersal are small, then females may leave groups as soon as within-group scramble competition begins to reduce their fitness (Gillespie and Chapman 2001;Dias and Strier 2003). If so, then studies of dispersal may provide a more sensitive measure of withingroup scramble competition than previous studies of female reproductive success (Watts 1990a(Watts , 1996Robbins et al 2007). This population has shown other evidence of withingroup scramble competition, such as longer feeding times in larger groups, but such increases were considered to be very small (Watts 1988(Watts , 1998.…”

Section: Introductionmentioning

confidence: 99%

“…For example, infanticide typically occurs when the silverback dies in one-male groups but not when the dominant male dies in multimale groups (ibid). Known cases of infanticide have claimed the lives of 10.4% of offspring born in onemale groups, which is significantly higher than 1.5% for offspring born in multimale groups (Fisher test, p=0.015, unpublished details from Robbins et al 2007). Infanticide protection has been considered as the main reason why gorillas form groups at all (Harcourt and Greenberg 2001;Harcourt and Stewart 2007).…”

Section: Introductionmentioning

confidence: 99%

“…Since then, the study groups have become three to five times larger than average, so this study should provide the clearest evidence of any effect from group size. However, no decline in female reproductive success was observed in those very large groups, thus providing no indication that group size is constrained by within-group scramble competition (Robbins et al 2007). For example, group size accounted for less than 0.1% of the variance in the average interbirth intervals of 39 females (p=0.87, ibid).…”

Section: Introductionmentioning

confidence: 99%

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Socioecological influences on the dispersal of female mountain gorillas—evidence of a second folivore paradox

Robbins

Stoinski

Fawcett

et al. 2008

Behav Ecol Sociobiol

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Socioecological models indicate that the group structure and female dispersal patterns of primates are determined primarily by the abundance and distribution of food, predation pressures, and infanticide risks. In response to those influences, females of folivorous primates are considered relatively free to disperse into groups with the optimal size and structure. Yet some folivores live in small groups despite a potentially higher risk of predation, an apparent inconsistency known as the folivore paradox. This paper examines the female dispersal of a folivorous primate, the Virunga mountain gorillas. Mountain gorillas currently have no natural predators, but this species presents a different version of the folivore paradox: why do 50-60% of females reside in smaller one-male groups despite a higher risk of infanticide? In this study, females left one-male groups more frequently than multimale groups, but transfer destinations were not consistently biased toward multimale groups and those groups did not have higher immigration rates. We found no evidence of dispersal to avoid feeding competition within large groups, even as they have become three to five times larger than average. Thus, the lack of a consistent bias toward multimale groups was not because they are typically larger than one-male groups. Instead, the apparent inconsistencies may reflect limited female transfer opportunities, other influences on dispersal, and possibly an evolutionary disequilibrium in which current behavior does not optimize fitness.

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Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Socioecological influences on the dispersal of female mountain gorillas—evidence of a second folivore paradox

Robbins

Stoinski

Fawcett

et al. 2008

Behav Ecol Sociobiol

Self Cite

View full text Add to dashboard Cite

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Maternal capital and the metabolic ghetto: An evolutionary perspective on the transgenerational basis of health inequalities

Wells¹

2009

American J Hum Biol

229

253

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There is particular interest in understanding socioeconomic and ethnic variability in health status. The developmental origins of disease hypothesis emphasize the importance of growth patterns across the life-course in relation to noncommunicable disease risk. The physiological components of cardiovascular risk, collectively termed the metabolic syndrome, derive in part from a disparity between the homeostatic "metabolic capacity" of vital organs and the "metabolic load" induced by large tissue masses, a rich diet and sedentary behavior. From an evolutionary perspective, the risk of such disparity is decreased by maternal physiology regulating offspring growth trajectory during gestation and lactation. Maternal capital, defined as phenotypic resources enabling investment in the offspring, allows effective buffering of the offspring from nutritional perturbations and represents the environmental niche initially occupied by the offspring. Offspring growth patterns are sensitive to the magnitude of maternal capital during early windows of plasticity. Offspring life-history strategy can then respond adaptively to further factors across the life-course, but only within the context of this initial maternal influence on growth. Maternal somatic capital is primarily gained or lost across generations, through variable rates of fetal and infant growth. I argue that the poor nutritional experience of populations subjected to colonialism resulted in a systematic loss of maternal capital, reflected in downward secular trends in stature. Accelerating the recovery of somatic capital within generations overloads metabolic capacity and exacerbates cardiovascular risk, reflected in increased disease rates in urbanizing and emigrant populations. Public health policies need to benefit metabolic capacity without exacerbating metabolic load.

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Physical maturation, life‐history classes and age estimates of free‐ranging western gorillas—insights from Mbeli Bai, Republic of Congo

Breuer

Hockemba

Olejniczak

et al. 2008

American J Primatol

156

138

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Physical maturation and life-history parameters are seen as evolutionary adaptations to different ecological and social conditions. Comparison of life-history patterns of closely related species living in diverse environments helps to evaluate the validity of these assumptions but empirical data are lacking. The two gorilla species exhibit substantial differences in their environment, which allows investigation into the role of increased frugivory in shaping western gorilla life histories. We present behavioral and morphological data on western gorilla physical maturation and life-history parameters from a 12.5-year study at Mbeli Bai, a forest clearing in the Nouabalé-Ndoki National Park in northern Congo. We assign photographs of known individuals to different life-history classes and propose new age boundaries for life-history classes in western gorillas, which can be used and tested at other western gorilla research sites. Our results show that western gorillas are weaned at a later age compared with mountain gorillas and indicate slower physical maturation of immatures. These findings support the risk-aversion hypothesis for more frugivorous species. However, our methods need to be applied and tested with other gorilla populations. The slow life histories of western gorillas could have major consequences for social structure, mortality patterns and population growth rates that will affect recovery from population crashes of this critically endangered species. We emphasize that long-term studies can provide crucial demographic and life-history data that improve our understanding of life-history evolution and adaptation and help to refine conservation strategies.

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Socioecological influences on the reproductive success of female mountain gorillas (Gorilla beringei beringei)

Cited by 83 publications

References 81 publications

Socioecological influences on the dispersal of female mountain gorillas—evidence of a second folivore paradox

Socioecological influences on the dispersal of female mountain gorillas—evidence of a second folivore paradox

Maternal capital and the metabolic ghetto: An evolutionary perspective on the transgenerational basis of health inequalities

Physical maturation, life‐history classes and age estimates of free‐ranging western gorillas—insights from Mbeli Bai, Republic of Congo

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