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The robust masticatory system of mountain gorillas is thought to have evolved for the comminution of tough vegetation, yet, compared to other primates, the toughness of the mountain gorilla diet is unremarkable. This may be a result of low plant toughness in the mountain gorilla environment or of mountain gorillas feeding selectively on low‐toughness foods. The goal of this paper is to determine how the toughness of the mountain gorilla diet varies across their habitat, which spans a large altitudinal range, and whether there is a relationship between toughness and food selection by mountain gorillas. We collected data on the following variables to determine whether, and if so how, they change with altitude: leaf toughness of two plant species consumed by mountain gorillas, at every 100 m increase in altitude (2,600–3,700 m); toughness of consumed foods comprising over 85% of the gorilla diet across five vegetation zones; and toughness of unconsumed/infrequently consumed plant parts of those foods. Although leaf toughness increased with altitude, the toughness of the gorilla diet remained similar. There was a negative relationship between toughness and consumption frequency, and toughness was a better predictor of consumption frequency than plant frequency, biomass, and density. Consumed plant parts were less tough than unconsumed/infrequently consumed parts and toughness of the latter increased with altitude. Although it is unclear whether gorillas select food based on toughness or use toughness as a sensory cue to impart other plant properties (e.g., macronutrients, chemicals), our results that gorillas maintain a consistent low‐toughness dietary profile across altitude, despite toughness increasing with altitude, suggest that the robust gorilla masticatory apparatus evolved for repetitive mastication of foods that are not high in toughness.
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Dental microwear reflects maturity-related feeding behavior in Virunga mountain gorillas.
Dental microwear reflects the abrasiveness of foodstuffs consumed by extant primates and it is commonly used to trace dietary adapta-tions in fossil hominins. However, the impact of feeding events and ecological constraints on micro-scale tooth wear formation processes remain unclear. Here, we use dental buccal-mi-crowear analysis to test age-related effects of physical food processing on tooth-use in a natu-rally accumulated skeletal assemblage from the well-documented population of mountain gorillas from Volcanoes National Park, Rwanda. We analyzed dental microwear pattern of single teeth belonging to individual skeletons: 14 decid-uous m2 (aged 1.2-6.08 years) and 39 permanent molars (~90% M2) of adult gorillas (10.69-44.55 years, 25 males and 14 females). Our results indicate that adult gorillas present more abraded molar buccal surfaces, with significantly higher densities and longer micro-striations, than imma-ture individuals, which reflects the abrasive potential of ingested foods and the micro-stria-tion cumulative process. However, we also found that dental buccal-microwear variability was not associated with age when only adult gorillas were considered. Thus, gorillas from this popula-tion present a stable microwear pattern through adulthood, despite intraindividual variability in feeding ecology. Our findings show the cumulative process of dental buccal-microwear as immature mountain gorillas increase their intake of solid foods and develop an adult diet; but also, the stability of this pattern when diet over time is stable. We confirm that dental buccal-microwear variability is a reasonable proxy for feeding ecology in primates, although seasonality, habitat variability and diet proportions at individual level should be considered in future studies.
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- PAR ID:
- 10504917
- Publisher / Repository:
- Wiley Periodicals LLC
- Date Published:
- Journal Name:
- American journal of biological anthropology
- Volume:
- 180
- Issue:
- S75
- ISSN:
- 2692-7691
- Page Range / eLocation ID:
- 58
- Format(s):
- Medium: X
- Location:
- USA
- Sponsoring Org:
- National Science Foundation
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