Young animals must resolve the conflicting demands of survival and growth, ensuring that they can function while developing towards their adult form. The ontogenetic relationship between cranium and mandible is of special interest because these two parts of the feeding apparatus must function in concert while both change along steep growth trajectories. Further, phenotypic plasticity in the feeding apparatus warrants investigation because variation in the emergent phenotype of the food processing apparatus has obvious implications for form and function, and important consequences for survival.This dissertation investigated morphological and behavioral development of coyotes. First, I examined ontogenetic changes in skull shape and the relationship between cranium and mandible, relative to key life-history events. In coyotes, there was synchrony of growth between cranium and mandible, and asynchrony of mandibular development; these patterns were also characteristic of spotted hyenas. However, coyotes had a much less protracted development than that in hyenas, and coyotes were handicapped relative to adults for a much shorter time. Morphological development did not predict life-history events in these two carnivores as it has in rodents. Second, I investigated the ontogeny of feeding performance and feeding biomechanics in coyotes. The results showed that the development of feeding performance was asynchronous with that of both feeding biomechanics and skull morphology and that this pattern was also characteristic of spotted hyenas. This developmental asynchrony suggests that a certain minimum threshold of physical growth and development, together with the associated development of biomechanics, are required to produce effective mastication. Third, I examined developmental plasticity in feeding behavior and feeding apparatus morphology by documenting variation in adult phenotypes due to experimental manipulation of diet. Variation in early bone processing opportunities lead to differences in adult skull shape, size and mastication musculature and this variation in morphology mediated the relationship between early diet and adult feeding performance. Fourth, I examined phenotypic plasticity in feeding apparatus morphology and feeding biomechanics through a comparison of captive and wild coyote skulls drawn from the same geographical area. Skull shape, skull size and length, and feeding biomechanics exhibited phenotypic plasticity in response to captivity. I demonstrated environmental effects on adult form, and such differences in form have implications for function. Collectively, the chapters in this dissertation provide a great deal of insight into developmental relationships between skull morphology and feeding behavior in Canis. Our results support the idea that developmental processes exhibit phenotypic plasticity, being sensitive to environmental effects. This results in variation in ontogenetic outcomes and has implications for both adult form and function.
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