© Koninklijke Brill NV, Leiden, 2010 DOI 10.1163/157075610X523279 Animal Biology 60 (2010) 395–412 brill.nl/ab Differences in sexual dimorphism among four gazelle taxa ( Gazella spp.) in the Middle East Torsten Wronski 1,2, *, Mohamed A. Sandouka 1,2 , Martin Plath 3, * and Peter Cunningham 1,2 1 Conservation Programmes, Zoological Society of London, Regent’s Park, London, NW1 4RY, United Kingdom 2 King Khalid Wildlife Research Centre, National Commission for Wildlife Conservation and Development, P.O. Box 61681, Riyadh 11575, Kingdom of Saudi Arabia 3 University of Frankfurt, Department of Ecology and Evolution, Frankfurt/M., Germany Abstract Sexual selection can lead to sexual dimorphism, where elaborated traits used in mate attraction or weap- onry are more expressed in the male sex. he degree of sexual dimorphism, however, is known to vary even among closely related taxa. Here we examined sexual dimorphism in horn length and three measures related to body size (body weight, shoulder height, and neck circumference) in four gazelle taxa, represent- ing at least three species, i.e. Dorcas gazelle ( G. dorcas), Sand gazelle ( G. subgutturosa marica) and Mountain gazelle ( G. gazella). he latter is represented by two distinctive phenotypes maintained and bred at the King Khalid Wildlife Research Centre in Saudi Arabia. We describe marked differences in sexual dimor- phism among taxa. For example, the difference in sexually dimorphic horn development was driven pri- marily by females exhibiting pronounced differences in horn development. We discuss how divergent mating systems, and group sizes affect these differences among the examined taxa, with more competition in larger groups probably promoting the evolution of larger horns in females, thereby leading to less sexual dimorphism. © Koninklijke Brill NV, Leiden, 2010. Keywords Gazelles; Arabian Peninsula; sexual selection; male-male competition; captive breeding Introduction Predicting the variation in the intensity of sexual and natural selection across species is a key challenge to evolutionary ecologists (Andersson, 1994; Shuster and Wade, 2003; Tobler et al., 2008). Sexual selection—either in the form of intra-sexual selection * ) Corresponding authors; email: t_wronski@gmx.de; Martin_Plath@web.de