P1.120 Wednesday, Jan. 4 Vertebral number is correlated with ecology in snakes (Squamata: Serpentes) MCCARTNEY, J.A.; Stony Brook University email@example.com
Lack of functional limbs in snakes has led to an increased importance for the trunk in locomotory and feeding behaviors. Because of this, the vertebral column is a likely source of variation related to ecology. Vertebral number, in particular, may vary with ecology; previous work suggests that snakes requiring greater flexibility (e.g., constrictors) have more vertebrae on average, and that snakes requiring greater stability (e.g., fossorial snakes) have fewer. This study investigates the relationships between ecological factors and vertebral number. Vertebral counts were collected from the literature and from new observations, and ecological data (habitat preference, constriction) were drawn from the literature. Snakes were sorted into four preferred habitats: terrestrial, arboreal, fossorial, and aquatic. A total of 292 species representing most families were included. The dataset was analyzed to determine what, if any, effect ecology had in selecting for vertebral number within groups. The results reveal that an Ornstein-Uhlenbeck model in which there is strong selection to maintain vertebral number at four separate optima (corresponding to the preferred habitats) was significantly better at explaining the data than either a single, global optimum or a two-optima model (constriction vs. non-constriction). A further phylogenetic generalized least squares analysis also reveals that constrictors have significantly more vertebrae than non-constrictors. Thus, vertebral number is significantly affected by both preferred habitat and constriction. The strong ecological signal shown here in the vertebral column is of potential interest in reconstructing the paleobiology of extinct snakes, particularly in combination with other morphological data.