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Dental anomalies suggest an evolutionary trend in the dentition of wolverine (Gulo gulo)

Jung, Thomas S., Rivest, Gabriel, Blakeburn, David A., Hamm, Emilie R., van Eyk, Aldo, Kukka, Piia M., Robitaille, Jean-François
Mammal research 2016 v.61 no.4 pp. 361-366
Gulo gulo, carnivores, diet, palate, skull, teeth, Canada
In mammals, congenital dental anomalies likely represent an evolutionary trend in the reduction of teeth (oligodonty) from the primitive dental formula. We quantified variation in the number of teeth from 421 wolverine (Gulo gulo) from northwestern Canada, focusing on polydonty (additional teeth), congenital oligodonty, and tooth rotation (misalignment). We predicted that oligodonty may be an evolutionary consequence of a previously reported increase in size of carnassial teeth since the Pleistocene. We also predicted that wolverine with missing or rotated teeth had smaller dental arcades than those without these anomalies. Oligodonty was observed in 42 wolverines (10 %), with the most cases involving the P¹ or P₁ (56 %) and P² or P₂ (32 %). We observed rotated teeth in 43 % of wolverines; virtually all of the rotated teeth we observed were P² or P₂. The frequency of oligodonty or rotated teeth was strikingly similar between the sexes. Both oligodonty and rotated teeth were observed more frequently in the mandibular than the maxillary toothrows. Most wolverine (67 %) with oligodonty were missing teeth unilaterally; in contrast, most animals with rotated teeth exhibited bilateralism (86 %). Condylobasal length and most measures of the dental arcade did not differ between wolverine with or without missing or rotated teeth; however, we found that skulls with missing or rotated teeth had narrower palate breadth ratios. Our data suggest that there may be an evolutionary trend in the loss of teeth at the anterior of the toothrows of wolverines, which may be a result of narrower dental arcades and larger carnassial teeth. Wolverine have a hypercarnivorous diet, and selection may be toward optimizing those teeth that contribute to securing and processing food (i.e., canine and carnassial teeth), and against those that likely do not contribute substantially to increasing fitness and survival, such as the P¹/P₁ and P²/P₂.