Pelvic shape variation among gorilla subspecies: Phylogenetic and ecological signals

Lawrence M Fatica; Sergio Almécija; Shannon C McFarlin; Ashley S Hammond

doi:10.1016/j.jhevol.2019.102684

Pelvic shape variation among gorilla subspecies: Phylogenetic and ecological signals

J Hum Evol. 2019 Dec:137:102684. doi: 10.1016/j.jhevol.2019.102684. Epub 2019 Oct 24.

Authors

Lawrence M Fatica¹, Sergio Almécija², Shannon C McFarlin³, Ashley S Hammond⁴

Affiliations

¹ Center for Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington, DC 20052, USA. Electronic address: lfatica@gwmail.gwu.edu.
² Division of Anthropology, American Museum of Natural History, New York, NY 10024, USA; Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici ICTA-ICP, c/ Columnes s/n, Campus de la UAB, Cerdanyola del Vallès, Barcelona, 08193, Spain; New York Consortium in Evolutionary Primatology (NYCEP), USA.
³ Center for Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington, DC 20052, USA; Division of Mammals, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA.
⁴ Division of Anthropology, American Museum of Natural History, New York, NY 10024, USA; New York Consortium in Evolutionary Primatology (NYCEP), USA. Electronic address: ahammond@amnh.org.

PMID: 31669913
DOI: 10.1016/j.jhevol.2019.102684

Abstract

Gorillas occupy habitats that range in elevation from 0 to 3850 m. Populations at higher elevations tend to be less arboreal than lowland populations. Variation in habitat-specific behaviors among closely related populations makes gorillas a unique model to study the relationship between locomotion and morphology. The pelvis reflects differences in locomotion in other primates, and thus may also reflect locomotor differences among gorillas. We tested the hypothesis that pelvic morphology exhibits clinal variation across elevation within Gorilla. Using 3D geometric morphometrics and principal components analysis (PCA), we characterized pelvic shape in three gorilla subspecies representing 14 localities across gorillas' full elevation range: western lowland gorillas (Gorilla gorilla gorilla), mountain gorillas (Gorilla beringei beringei), and Grauer's gorillas (Gorilla beringei graueri). We found that the first principal component (PC1) usually reflects differences between western and eastern gorillas in the lateral margin of the ilium and, in males, the obturator foramen. When sexes are considered together, the second principal component (PC2) indicates some separation between G. b. beringei and G. b. graueri, albeit with considerable overlap, corresponding to the shape of the iliac crest. When sexes were analyzed separately, there was no distinction. Phylogenetic generalized least squares regression was used to evaluate the relationship between elevation and pelvic shape under varying phylogenetic assumptions. Models were compared to assess how phylogenetic adjustment affects model fit. Neither of the first two PCs nor overall shape yielded a significant relationship with elevation in any of the pooled-sex and individual-sex samples. This suggests that covariation between pelvic morphology and elevation is sex-specific and dependent on phylogenetic assumptions. Our results find complex interactions between sex, phylogeny, elevation, and pelvic morphology, suggesting that there is not one ecomorphological pattern that characterizes all gorillas.

Keywords: Ecomorphology; Gorilla; Neutral evolution; Os coxae; Pelvis.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Altitude
Animal Distribution*
Animals
Ecosystem
Female
Gorilla gorilla / anatomy & histology*
Male
Pelvic Bones / anatomy & histology*
Pelvis / anatomy & histology*
Phylogeny
Sex Characteristics