Bite force and encephalization in theCanidae (Mammalia:Carnivora)

Abstract

AbstractThe ways in which the taxonomic differences in morphology, behavior or life history relate to each other have been used regularly to test ideas about the selective forces involved in their evolution. Canid species vary significantly in diet, hunting techniques, sociality and cranial morphology. The main goal of this study is to test and explore the possible correlation between bite force and brain volume in canids. For that, we calculated the bite force based on the beam theory, and the brain volume based on three cranial measurements. The species with biggest values of bite force quotient (BFQ) wereSpeothos venaticus(162.25),Cuon alpinus(129.24) andLycaon pictus(124.41) due to several adaptations acquired along with hypercarnivory. Species with the highest values of brain volume quotient (BVQ) wereS. venaticus,Cu. alpinusandL. pictuswith, respectively, 141.35, 139.01 and 131.61, possibly due to the same adaptations that resulted in their biggerBFQ. The highest values of bite force belonged toCanis lupus(830.51 Pa),L. pictus(719.03 Pa) andCa. rufus(530.52 Pa) and the smallest values belong toUrocyon littoralis(98.14 Pa),Vulpes macrotis(92.53 Pa) andV. zerda(72.6 Pa).Ca. lupus,L. pictusandChrysocyon brachyuruspossess the largest brain volumes with respectively 159.29, 146.94 and 120.84 mm3and the smallest values belong toNyctereutes procyonoides(28.2 mm3),V. rueppelli(27.86 mm3) andV. zerda(20.65 mm3). The independent contrasts correlation showed that there is no correlation betweenBVQandBFQ(r = 0.14/P= 0.46), as well as no correlation betweenBFQandBF(r = 0.22/P= 0.26), which indicates the efficiency of the size correction. Bite force and brain volume estimates are much higher in the group hunting hypercarnivores (Lycaon,CuonandSpeothos) and only these showed correlation betweenBFQandBVQ. Our results indicate that cranial adaptations for hypercarnivory also influence braincase size.