Directional and fluctuating asymmetries in domestic sheep skulls

Parés-Casanova P. M., Bravi R.

Abstract


Morphological symmetry and asymmetry of three different sheep geographical populations (n=39), managed under semi-extensive conditions, were decomposed using geometric morphometric methods, on dorsal aspect of skulls. Fluctuating asymmetry (FA) was used as an indicator of environmental stress, and directional asymmetry (DA) as biomechanical constraints. The two-dimensional coordinates of 21 landmarks were digitized and analyzed using geometric morphometrics. Multivariate analyses showed the presence of subtle but significant directional asymmetry and fluctuating asymmetry in the entire sample, but no distinctive differences were detected between populations. These results are on the whole indicative that environmental stress, if present was not sufficient to infer on symmetry of the skull, and no alterations could be noted on functional loadings. On the whole morphometric studies should open up promising areas of research in this almost unexplored field, in domestic ungulates.

 

Key words: geometric morphometric, morphological variation, Ovis, symmetry


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