33.5 Thursday, Jan. 5 A revised metric to quantify body shape diversity in vertebrates REYNAGA, Crystal/M*; COLLAR, David/C; WARD, Andrea/B; MEHTA, Rita/S; Univ. of California, Santa Cruz; Univ. of California, Santa Cruz; Adelphi Univ.; Univ. of California, Santa Cruz email@example.com
Vertebrates exhibit tremendous variation in body shape, though quantifying this diversity has been challenging. In the past, researchers have characterized shape diversity with multivariate statistics and various simplified metrics of body shape such as, elongation ratio (ER), fineness ratio (FR), and axial elongation index (AEI). While ER and FR are useful for describing overall shape, they provide little insight into the anatomical bases of shape variation. AEI describes the morphology of the underlying axial skeleton but may have only a weak correlation with overall body shape. In this study, we present a new metric of body shape, the Vertebrate Shape Index (VSI), which describes shape using morphological features common to all vertebrate taxa: head length, the 2nd longest body axis (width or depth), vertebral number and the shape of individual vertebrate. We illustrate the usefulness of VSI on a data set of 140 species representing several major vertebrate groups (Actinopterygii, Amphibia, Reptilia, Aves, and Mammalia). We also show how different animal preparations can be used to obtain the variables that comprise VSI by gathering data from radiographs, articulated skeletons, and cleared and stained specimens. Our study quantitatively describes body shape variation for a diverse sample of vertebrate taxa and highlights the relative importance of head length, second major axis (body depth/width), and vertebral characteristics as independent contributors to overall body shape diversity in vertebrates.