The contribution of functional traits to the understanding of palaeoenvironmental changes

Résumé En

Performance traits implicated in feeding interact directly with the environment and are consequently relevant ecological indicators. However, they have rarely been used to better understand palaeoenvironmental variation. Here, we evaluate the usefulness of a performance (i.e. functional) trait, estimated bite force, in reconstructing the palaeoecology of shrews. We investigate the relationships between mandible morphology, bite force estimates and the ecological context. We use geometric morphometrics to quantify mandible shape diversity in shrews of the archaeological site El Harhoura 2 (Rabat, Morocco), dated from the Late Pleistocene to the Holocene. Morphological groups were used instead of taxa as units of diversity. To explore how phenotypic traits are linked to their environment, they were compared with palaeoenvironmental inferences for the El Harhoura 2 site extracted from the literature. Morphological groups acted as phenotypic response units. Estimated bite force was related to palaeoenvironmental variation over the considered period, with a particular sensibility to arid/humid transitions. The complementarity of morphological and performance indicators allowed us to infer functional convergence and divergence among shrews. Our results suggest that functional traits may be relevant indicators of changes in palaeoenvironments. This approach opens up new possibilities to explore the impact of environmental changes on extinct organisms.