Understanding how ecological variation shapes skeletal morphology is important for linking observed locomotor behavior to anatomical correlates in extant hominoids, and for the subsequent interpretation of locomotor behavior in extinct taxa. In this study, we investigate ecomorphological variation in the metacarpals and phalanges across all five manual rays within Gorilla, focusing particularly on differences between western lowland gorilla (Gorilla gorilla gorilla) and the Rwandan (Volcanoes National Park) and Ugandan (Bwindi Impenetrable National Park) populations of mountain gorilla (Gorilla beringei beringei). This work incorporates the first substantial set of skeletal measurements from the Bwindi mountain gorilla population, derived from individuals recovered by the Mountain Gorilla Skeletal Project between 2018 and 2025. By comparing these data with samples from low and high-elevation Grauer's gorillas (Gorilla beringei graueri), we assess how variation in arboreality correlates with digit element lengths, demonstrating that the Bwindi mountain gorillas exhibit intermediate metacarpal and phalangeal lengths between the more arboreal western lowland gorillas and the more terrestrial Virunga mountain gorillas. These findings indicate a correlation between longer digital rays in more arboreal populations, even within the same species, which may enhance grasping and stability on arboreal substrates. We show a population-specific relationship between ecology and hand morphology in Gorilla and emphasize the value of documenting localized skeletal responses to environmental and behavioral variation to better interpret patterns in the hominoid fossil record.
Greiner et al. (Sun,) studied this question.