Parallel Evolution of Skull Form in Three Rodent Genera Inhabiting Steep Elevational Gradients of Ethiopian Highlands

Abstract Several rodent genera radiated in Ethiopian highlands during Pleistocene, giving rise to species specialized different elevation zones. The zonation is accompanied by vegetation change from savannahs or forests lower elevations, through the mid-elevation belt of ericaceous shrublands Afroalpine moorlands on mountain tops. Such evolution gradient expected promote phenotypic adaptations and several are known include highly distinctive high-elevation specialists. In this study, we systematically examined shape size differentiation skull mandible three genera, Lophuromys , Arvicanthis Stenocephalemys each including six eight inhabiting zones both sides Great Rift Valley. Employing computed tomography, three-dimensional virtual models, landmark-based geometric morphometrics a powerful toolkit partial least squares analysis, demonstrated elevation-related prominent feature variation all genera. We identified parts which most between successive These include, notably, orbits insertion areas masticatory muscles, suggests adaptive shifts visual perception diet. also showed that while same modified they ways degree. evidence for was mixed despite universal trend larger higher elevations. Our study confirms specialists represent forms, especially true Bale Arsi Mountains, East