Sexual dimorphism in the skull of Spanish ibex Capra pyrenaica Schinz, 1838 is analyzed by means of univariate and multivariate techniques in one of the most representative populations of the species, located in the Sierra de Gredos, central Spain. Thirty eight measurements were used for the analysis: 30 of the skull and mandible, and 8 of the horn. Eighty three skulls (40 males and 43 females) of individuals older than 4 years were used. In 36 out of the 38 variables males were significantly larger than females. Horn characters showed the highest variability and also the most significant differences between sexes. Values of Mahalanobis distance between males and females were high (D2 = 323.1). When Factor Analysis is performed with the whole set of 38 variables, 7 Principal Factors were extracted, scores of Principal Factor 2 (related with horn variables) and Principal Factor 3 {related to molar toothrow length) showing significant differences between sexes. In this analysis, horn characters (Principal Factor 2) accumulate the sexual dimorphism of other skull traits. However, if the same analysis is performed without horn characters, 5 Principal Factors were extracted, scores of three Principal Factors showing significant differences between sexes. Highest sexual dimorphism in this analysis corresponds to the Principal Factor 3 (molar toothrow), follow the Principal Factor 2 (posterior region of the skull) and Principal Factor 1 (main length measurements). This suggest that the high degree of sexual dimorphism observed in the Spanish ibex skull is mainly related to horn traits and, to a lesser extent, of other skull features like molar toothrow length.
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