Meeting Abstract
Very little is known about the functional morphology of the mammalian neck. The primary function of the mammalian neck is to help maintain a stable head and visual field. A steady head is especially important for successful foraging and hunting. Species that rely on different resources should be under different evolutionary pressures with regard to range of motion of the head and neck. I hypothesize that habitual feeding behaviors should affect the maximum range of motion of the axial skeleton. Species relying on mobile, agile food sources should have greater maximum ranges of motion in order to accommodate hunting behaviors. In contrast, frugivorous and nectivorous species should not require large excursions of the head and neck for feeding. As such, these latter species should experience greater head and neck stability both during locomotion and other behaviors. Maximum head and neck range of motion were collected from fifteen species of wild-caught Neotropical bats (n=39) in Orange Walk District, Belize. To collect ranges of motion, individuals were held flush to a table. Using a dowel, the head and neck were manipulated into maximum flexion and extension while maintaining the first thoracic vertebra in a stationary position. Photographs were taken at maximum flexion, extension, and a self-selected neutral position. Angular measurements were taken from the photographs using ImageJ. A phylogenetic tree was constructed from molecular data and used to conduct a phylogenetic ANOVA. Results show that insectivorous species have a significantly larger maximum range of head and neck motion than frugivorous species indicating that dietary behavior is a significant evolutionary pressure on neck function and, therefore, cervical vertebral morphology. This in turn should affect the maintenance of head stability.
