Side differences in the skull of sheep: an assessment by geometric morphometrics
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Effects of perturbations during development can be due to environmental and/or genetic factors, resulting in increased developmental instability which in turn can be expressed as fluctuating asymmetry (FA), defined as the non-directional deviation (right-left differences) from bilateral symmetry. However, other asymmetry types can appear, such as and directional asymmetry (DA), characterized by a distribution skewed to one side (right or left) at the, which is originated as a response to external stimuli that affect differentially on both sides of the organism. In order to describe asymmetric patterns in the ovine skull, we studied 165 specimens from animals belonging to the sheep breed 'Navarra' from North Spain, using geometric morphometric methods. On digital pictures, we analyzed two midline and 8 bilateral two-dimensional landmarks on skull dorsal aspect. Results showed that FA accounted for a reduced amount of total variation, while DA explained most of it. We suggest that the presence of side differences due to lateralized muscular function (mastication) is the most important factor in skull asymmetry. Obtained results should provide a basis for relating asymmetries to the mechanics of cranial skeletum in sheep.
Is part ofAnnual Research & Review in Biology, 2019, vol. 34, num. 2, p. 1-7
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Except where otherwise noted, this item's license is described as cc-by (c) Parés Casanova et al., 2019
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Parés Casanova, Pere-Miquel; Bravi, R. (Medlife Scientific Press, 2014-06-22)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. ...
Parés Casanova, Pere-Miquel; Ardiaca, Jordi; Martínez Silvestre, Albert (Societas Europaea Herpetologica (SEH), 2020-08-05)Bilateral symmetry is not uncommon in animal kingdom, and animals can deviate from expected symmetry and manifest some forms of asymmetries. Fluctuating asymmetry is considered a tool for valuating developmental instability, ...
Parés Casanova, Pere-Miquel (Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia, 2019-07-03)Organisms can develop different kinds of asymmetry when deviations from expected perfect symmetry occur. Among others are fluctuating asymmetry (FA) and directional asymmetry (DA). FA represents small random differences ...