Integration or Modularity in the Mandible of Canids (Carnivora: Canidae): a Geometric Morphometric Approach

Understanding the interplay between morphological integration and modularity is considered an important topic in the study of the evolution of the form of complex structures. The mandible is a complex structure that can be shaped by diverse factors such as ontogeny, ecology, and evolutionary history. In canids, this is particularly interesting because they have a large diversity in feeding behavior and hunting strategy. Here, we employed geometric morphometric techniques to evaluate the balance between integration and modularity in 1011 mandibles of a sample of extinct and extant canids. The results show that allometric scaling seems to have little influence in determining the mandibular shape of canids. Some divergence associated with ecology was observed, especially for highly specialized taxa (hypercarnivores and insectivores). Finally, macroevolutionary patterns were more integrated than intraspecific patterns, suggesting that correlational selection might play a strong role in the evolution of mandibular form and function. We found no evidence of an evolutionary line of least resistance in shaping mandible disparity.