How environment affects the relationship between craniomandibular morphology and diet: community ecomorphology of five sigmodontine rodent assemblages from central-eastern Argentina

Abstract Many studies aim to understand the relationships between morphology and ecology. However, this relationship and its potential adaptive nature are fundamentally dependent on the context where a species lives. The sigmodontine rodent assemblages from central-eastern Argentina, comprising over 20 taxa with varied morphology and ecology living in several diverse environments, are an excellent model to study this complex relationship. We studied five assemblages (21 species, 579 specimens), integrating craniomandibular morphology, diet and environmental variables. Using linear morphometrics and multivariate statistics, we assessed size and shape of crania and mandibles. Upon incorporating dietary information, we plotted the assemblage’s ecomorphospaces, observing partial segregation of species associated with dietary habits. Furthermore, overlap patterns varied among assemblages. When analysed considering environmental data, assemblages from environments with high productivity and low seasonality displayed higher morphological segregation among dietary groups, and overlap among groups increased as productivity decreased. We suggest that sigmodontine assemblage structuring is strongly influenced by the interplay between environmental conditions, craniomandibular morphology and dietary specialisation. More stable, nutrient-rich environments would be able to sustain morphologically and ecologically specialised species, whereas environments where food is temporarily less stable support only more generalised species.