Dietary Abrasiveness Is Associated with Variability of Microwear and Dental Surface Texture in Rabbits

Abstract

Dental microwear and 3D surface texture analyses are useful in reconstructing herbivore diets, with scratches usually interpreted as indicators of grass dominated diets and pits as indicators of browse. We conducted feeding experiments with four groups of rabbits (Oryctolagus cuniculus) each fed a different uniform, pelleted diet (lucerne, lucerne & oats, grass & oats, grass). The lowest silica content was measured in the lucerne and the highest in the grass diet. After 25 weeks of exposure to the diets, dental castings were made of the rabbit's lower molars. Occlusal surfaces were then investigated using dental microwear and 3D areal surface texture analysis. In terms of traditional microwear, we found our hypothesis supported, as the grass group showed a high proportion of (long) “scratches” and the lucerne group a high proportion of “pits”. Regardless of the uniform diets, variability of microwear and surface textures was higher when silica content was low. A high variability in microwear and texture analysis thus need not represent dietary diversity, but can also be related to a uniform, low-abrasion diet. The uniformity or variability of microwear/texture analysis results thus might represent varying degrees of abrasion and attrition rather than a variety of diet items per se.

Seeds, browse, and tooth wear: a sheep perspective

“…The few previous studies have not focused on frugivory and granivory but on diet abrasiveness with a 32‐rabbit model (Schulz et al. 2013) and the phytolith/dust debate with a 4‐ewe model (Hoffman et al. 2015).…”

Controlled feeding trials with ungulates: a new application of in vivo dental molding to assess the abrasive factors of microwear

“…However, several studies examining the effects of biogenic and abiotic abrasives have cast doubt on the central role of biogenic silica in scratch accumulation (Covert and Kay, 1981;Kay and Covert, 1983;Maas, 1991Maas, , 1994Gügel et al, 2001;Mainland, 2003;Sanson et al, 2007;Lucas et al, 2013;Schulz et al, 2013;Müller et al, 2014). Whereas an early study of material properties showed phytoliths were harder than sheep tooth enamel (Baker et al, 1959), subsequent nanoindentation tests have found phytoliths from four globally widespread species of grass to be softer than enamel (Sanson et al, 2007).…”

“…Similarly, rabbits (Oryctolagus cuniculus) fed grass diets of increasing biogenic abrasiveness (i.e. higher phytolith content) showed higher relative scratch counts, greater variability among individuals (Schulz et al, 2013) and increased rates of tooth wear (Müller et al, 2014). Tooth wear rates also increased when rabbits were fed diets with abiotic abrasives (i.e.…”

The phylogenetic signal in tooth wear: What does it mean?

“…Further, experimental studies have demonstrated different microwear attribute values in the same species when fed foods with different textural properties and/or grit loads (e.g. Schulz et al, 2013; Merceron et al, 2016). In many cases, the diets of extinct taxa are also vastly different from those of extant taxa, despite being members of the same family (e.g.…”