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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptNIH Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
 
J Morphol. Author manuscript; available in PMC Mar 15, 2011.
Published in final edited form as:
PMCID: PMC3057660
NIHMSID: NIHMS273023
Directional Asymmetry in the Limbs, Skull and Pelvis of the Silver Fox (V. vulpes)
Anastasia V. Kharlamova,1 Lyudmila N. Trut,1 Kevin Chase,2 Anna V. Kukekova,3 and Karl G. Lark2*
1 Institute of Cytology and Genetics, Siberian Branch Russian Academy of Science, Novosibirsk, Russia
2 Department of Biology, University of Utah, Salt Lake City, Utah
3 Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York
* Correspondence to: Karl G. Lark, Department of Biology, University of Utah, 257 South 1400 East, Rm. 201, Salt Lake City, UT 84112. lark/at/bioscience.utah.edu
Abstract
Directional asymmetry (DA) is a characteristic of most vertebrates, most strikingly exhibited by the placement of various organs (heart, lungs, liver, etc.) but also noted in small differences in the metrics of skeletal structures such as the pelvis of certain fish or sauropsids. We have analyzed DA in the skeleton of the fox (V. vulpes), using ~1,000 radiographs of foxes from populations used in the genetic analysis of behavior and morphology. Careful measurements from this robust data base demonstrate that: 1) DA occurs in the limb bones, the ileum, and ischium and in the mandible; 2) regardless of the direction of the length asymmetry vector of a particular skeletal unit, the vectorial direction of length is always opposite to that of width; 3) with the exception of the humerus and radius, there is no correlation or inverse correlation between vectorial amplitudes or magnitudes of bone asymmetries. 4) Postnatal measurements on foxes demonstrate that the asymmetry increases after birth and continues to change (increasing or decreasing) during postnatal growth. 5) A behavior test for preferential use of a specific forelimb exhibited fluctuating asymmetry but not DA. None of the skeletal asymmetries were significantly correlated with a preferential use of a specific forelimb. We suggest that for the majority of fox skeletal parameters, growth on the right and left side of the fox are differentially biased resulting in fixed differences between the two sides in either the rate of growth or the length of the period during which growth occurs. Random effects around these fixed differences perturb the magnitude of the effects such that the magnitudes of length and width asymmetries are not inversely correlated at the level of individual animals.
Keywords: fox, V. vulpes, skeleton, directional asymmetry, pelvis, mandible, limb bone