VARIATION IN METATARSAL MORPHOLOGY AMONG SUBGROUPS OF NORTH AMERICAN MOOSE (Alces alces)

Abstract

The objectives of this study were to characterize variation in dimensional data from the metatarsus of 4 different subpopulations of North American moose (Alces alces) that are known to differ in stature, and to determine if specific metatarsal width measurements (proximal, middle, distal) can be used to accurately predict metatarsal length in these subpopulations. We found that subpopulations differ in the dimensions of their metatarsal bones. Alaskan moose (A. a. gigas) are significantly larger in the length and width of the metatarsus than non-Alaskan moose. Moose from Isle Royale have significantly shorter metatarsal bones than the other groups which is associated with a proportional reduction in the middle metatarsal width; the ratio of middle width:length was similar across groups in contrast to the proximal: and distal width:length ratios. These dimensions were not reduced proportionally in Isle Royale specimens as these ratios were greater in the Isle Royale moose than in other groups. Predictive equations for estimating metatarsal length from each of the 3 width measurements were developed. The length could be predicted accurately from each of the width measurements if separate predictive equations were developed for specimens collected from Isle Royale versus the other subgroups. These data indicate that considerable variation exists in the dimensions of a single bone, the metatarsus, in subgroups of the same species. Valid predictive equations developed using data sets from one subgroup may not provide accurate predictions when applied to other subgroups of the same species.