Dental microwear texture analysis of extant sika deer with considerations on inter-microscope variability and surface preparation protocols

Recently, dental microwear texture analysis (DMTA) has been applied to various kinds of vertebrates to infer dietary preference. More data are needed on inter-microscope variability to assure the objectivity and repeatability of this method. In the present paper, we investigated inter-microscope variability between two confocal laser microscopes with different specifications, as well as variability due to different protocols applied to the obtained surface before DMTA. We used two different methods of DMTA: the scale sensitive fractal analysis (SSFA) and the surface texture analysis (STA). We collected DMTA data of extant Japanese sika deer populations with varying diets. We found that different protocols produced significantly different results for both SSFA and STA, whereas nearly two thirds of the parameters were not significantly different between the machines when applying the same pre-analysis protocol. Finally, we analyzed DMTA data of 244 sika deer from 11 populations. Twenty nine parameters were significantly different among the populations. Tooth enamel surface of grazing sika deer is dominated by a number of well-aligned scratches, whereas that of browsing deer is more flattened and characterized by more sporadic pits. Therefore, DMTA can identify intraspecific variation in diets, which is smaller than the interspecific dietary variation in extant ruminants.