Craniofacial Fluctuating Asymmetry in Cross River Gorillas ( Gorilla gorilla diehli )
Year: 2026
Type: article
Abstract: OBJECTIVES: Craniofacial fluctuating asymmetry (FA) in gorillas has been linked to environmental and/or genetic stress. Prolonged population declines increase levels of inbreeding, leading to developmental instability, which can manifest as FA. Among gorillas studied to date, craniofacial FA levels are highest in mountain gorillas (G. beringei beringei) and lowest in western lowland gorillas (G. gorilla gorilla), reflecting known levels of genetic diversity and inbreeding in these subspecies. This study assessed craniofacial FA in Cross River gorillas (G. gorilla diehli), a little-known subspecies with high levels of inbreeding due to a recent genetic bottleneck. MATERIALS AND METHODS: Thirty fixed landmarks of the craniofacial skeleton were used to assess FA in 30 Cross River gorillas using Procrustes ANOVA. Principal component analysis assessed variation in both symmetric and asymmetric components. Differences in FA magnitudes between Cross River gorillas and published data for other Gorilla subspecies were assessed using permutation tests. RESULTS: Craniofacial FA accounts for 9.9% of shape variation in Cross River gorillas, whereas directional asymmetry accounts for 0.5%. Allometry accounts for 14.1% of shape variation in the symmetric component and 3.8% in the asymmetric component. Craniofacial FA magnitudes are higher in Cross River gorillas than in western lowland gorillas and lower than in mountain gorillas. DISCUSSION: High FA in Cross River gorillas aligns with known levels of inbreeding, supporting the link between genetic stress and craniofacial FA in gorillas. Persistent inbreeding and the loss of genetic diversity may decrease population fitness, further increasing the risk of extinction.
DOI: 10.1002/ajpa.70233
Institutions: A.T. Still University, George Washington University, Centro Nacional de Investigación sobre la Evolución Humana, University of Indianapolis, Monash University, Centre National de la Recherche Scientifique, University of Cambridge, Histoire Naturelle des Humanités Préhistoriques, Musée de l'Homme, De la Préhistoire à l'Actuel : Culture, Environnement et Anthropologie, King's College London, Smithsonian Institution, National Museum of Natural History, University of Wollongong, Lakehead University, University College London, The Dian Fossey Gorilla Fund International, University of California, Berkeley, Royal Museum for Central Africa, Université Libre de Bruxelles, Rwanda Development Board, University of Arizona College of Medicine- Phoenix, Arizona State University
Language: English
Subfield: Geometry and Topology
Field: Mathematics
Domain: Physical Sciences
Open Access status: green
Awards: Collaborative Research: Hard Tissue evidence of weaning variation in primates, Socioecological factors and patterns of growth and development in two gorilla species, G4948453788, Skeletal Preservation and the Life History of Virunga Mountain Gorillas, Mineralized tissue research on the life history of Virunga mountain gorillas
OpenAlex ID: W7150894546