Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence

Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil vertebrates.Nevertheless,some studies have recently questioned the efficacy of this approach,suggesting that aspects of habitat unrelated to food preference,especially environmental grit load,might have a confound­ing effect on microwear patterning that obscures the diet signal.Here we evaluate this hypothesis by examining microwear textures of 3 extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types:Mastomys coucha,Micaelamys namaquensis and Rhabdomys pumilio.We sample each of these species from 3 distinct environmental settings in southern Africa that differ in rainfall and vegetative cover:Na­ma-Karoo shrublands(semi-desert)and Dry Highveld grasslands in the Free State Province of South Africa,and Afromontane(wet)grasslands in the highlands of Lesotho.While differences between habitat types are ev­ident for some of the species,inconsistency in the pattern suggests that the microwear signal is driven by vari­ation in foods eaten rather than grit-level per se.It is clear that,at least for species and habitats sampled in the current study,environmental grit load does not swamp diet-related microwear signatures.