Functional Morphology of the Oral Jaws and Dentition Across Diverse Diets and Ontogeny in Prickleback Fishes (Stichaeidae)

Pricklebacks (Stichaeidae) are a useful model for studying dietary diversity in fishes. Several species integrate increasing amounts of plant material into their diets as they grow, which is matched by physiological adaptations and allometric growth of the digestive tract to enhance the digestion of plant material. Similar to physiological differences, there are varying mechanical demands of eating plants compared to a carnivorous diet; we hypothesize that oral jaw morphology, dental characteristics, and tooth functional variation reflect diverse diets in pricklebacks. To explore this relationship, we first captured high-resolution jaw and dentition morphology using microCT scanning across four species of prickleback over ontogeny (n = 9 per species), and 3 outgroups (n = 3 per species). We compared traits between species and quantified the scaling of these traits over ontogeny. We then use linear discriminant analyses to identify traits that drive differences between dietary groups. Pricklebacks span a range of jaw and tooth morphotypes from large jaws with many villiform teeth, to short jaws with large, rounded teeth. While there is overlap between groups, we find several traits define dietary groups and diverge via allometry. However, comparison with outgroups reveals high morphological diversity within each dietary group.