PHENOTYPIC PLASTICITY IN SKULL AND DENTAL MORPHOLOGY IN THE PRAIRIE DEER MOUSE (PEROMYSCUS-MANICULATUS BAIRDII)

Morphologists and systematists have long suspected that dietary consis tency can affect skull and dental form in mammals. We examined plastic ity of skull shape and tooth morphology in prairie deer mice (Peromysc us maniculatus bairdii) by feeding mice diets that differed in consist ency but not nutritional quality. Shape differences were analyzed qual itatively and quantitatively, using both landmark-based morphometrics and traditional distance measurements. Mice fed a gruel made of labora tory chow soaked in water differed from those fed hard blocks of chow by a slight anterior shift in the incisor tips, a narrowed zygomatic p late, a reduction in size of the masseteric tubercles, an overall decr ease in skull size in lateral view, and an increase in overall size in ventral view. Disparities between our results and previous studies ma y be due to the differences in behavior between the inbred, relatively inactive laboratory strains commonly used in experimental studies and the outbred, constantly active species used here. Also, in contrast t o previous studies, the statistical analysis employed here took into a ccount both family relationships of the animals and the large number o f statistical comparisons performed. Failure to consider these factors would have resulted in an exaggerated estimate of the effects of diet on skull form and may taint other studies that have explored the same aspects of plasticity. (C) 1996 Wiley-Liss, Inc.