Matěj Lövy, Radim Šumbera, Barbora Konopová, Lucie Svačinová, Josef Bryja, Yonas Meheretu, Ondřej Mikula
Journal of Vertebrate Biology 73 (24027), 24027.1-20, (30 July 2024) https://doi.org/10.25225/jvb.24027
KEYWORDS: skull, mandible, foraging ecology, locomotion, mammals, Ethiopian Highlands, rodents
Rodents comprise around half of all mammalian species, showcasing their remarkable adaptability to thrive in almost all terrestrial habitats. Their evolutionary success is exemplified by a wide range of morphological features reflecting various feeding and locomotory adaptations. This study examines the functional variation in cranial and mandibular traits as well as locomotion indices in rodent communities within the high-altitude Afroalpine environment of the Ethiopian Highlands. The findings reveal two distinct patterns in cranial and mandibular traits. One pattern is associated with dietary differences, distinguishing the primarily herbivorous species Otomys helleri, Arvicanthis abyssinicus and Lophuromys melanonyx, which are characterised by relatively long molar rows, massive mandibles, and likely enhanced bite force, from the generally omnivorous genus Stenocephalemys and the more faunivorous Lophuromys flavopunctatus. The second pattern indicates that species in the Afroalpine ecosystem have adapted to life in distinct habitats across different elevational zones. Species from the highest elevational zones within the genera Stenocephalemys and Lophuromys exhibit convergent morphological adaptations for life in open habitats, characterised by their larger size, narrower interorbital constriction, and larger orbits. Regarding locomotion, our study emphasises the unique morphology of Otomys, which is characterised by equally long forelimbs and hindlimbs. This corresponds to its predominant fast quadrupedal running. In contrast, Stenocephalemys species are likely to rely more on saltatory locomotion. Among them, the forest-dwelling S. albipes likely demonstrates the most advanced form of this locomotory style. The study highlights significant functional diversification in rodent assemblages from the Ethiopian Highlands, primarily driven by foraging and locomotor ecologies. This morphological variation has likely contributed to shaping the rich rodent communities integral to the Eastern Afromontane Biodiversity Hotspot, globally recognized for its significance in mammal endemism.