Head Shape and Size in Cannibal and Noncannibal Larvae of the Tiger Salamander from West Texas

Abstract

The relationships among 12 measures of head size and body size were investigated in large morph, small morph and cannibal morph tiger salamanders from west Texas (A. t. mavortium). Since all cranial characteristics were correlated with body size, the allometric relationship between each character and body size was examined. Allometric regressions for large morphs and small morphs did not differ in slope or Y-intercept and data for these 2 groups were pooled for comparison with cannibals. Each cannibal allometric regression had a lower slope than the corresponding noncannibal regression, but these differences were not significant. The Y-intercepts of cannibal regressions exceeded the Y-intercept of the appropriate noncannibal regression. These findings suggest that head size does not increase at a faster rate relative to body size in cannibals, but that cannibals begin with a larger head early in ontogeny.