Meeting Abstract
Skeletal elements can reshape to resist forces encountered in the environment. This response may allow the shape of a bone to adapt plastically in parallel to the way natural selection would allow it to adapt evolutionarily. We studied the degree of shape difference in the distal digits (unguals) of wild and captive ruminants (Mammalia, Artiodactyla) to determine the extent to which plastic responses are expected in the locomotor system. Zoos have a greater proportion of cement, packed earth, and other hard materials many ruminant species would not naturally traverse; therefore we would expect a significant difference in the ungual shape of captive animals, regardless of species, if plastic response is an important mechanism of locomotor specialization. We analyzed shape differences in the plantar surface of two unguals from three wild and three captive individuals of 13 ruminant species. Outlines with 100 semilandmark points were Procrustes superimposed to produce shape variables for subsequent analysis. On average there was no difference between captive and wild individuals (p=0.15, permutation test). However, species varied significantly in the degree to which ungual shape responded to captivity (p= 0.0316, species × captivity interaction, two-way MANOVA). Captivity had the greatest effect on giraffids and the least effect on big horned sheep. Surprisingly the magnitude of the effect does not appear to be related to the degree of difference between natural and captive environments. Compared to between species mean differences, the effects of captivity were small. Results suggests that ungual plasticity is not as significant in locomotor specialization as long-term adaptation, but still reveal that plasticity is higher in some species for reasons that are not yet apparent.
