Cats and dogs cross the line: domestic breeds follow Rensch’s rule, their wild relatives do not

• Published in: Vavilovskiĭ zhurnal genetiki i selekt͡s︡ii Vol. 21; no. 4; pp. 443 - 451
• Main Authors: Bidau, C. J., MartÍnez, P. A.
• Format: Journal Article
• Language: English
• Published: Siberian Branch of the Russian Academy of Sciences, Federal Research Center Institute of Cytology and Genetics, The Vavilov Society of Geneticists and Breeders 2017
• Subjects: body size; canidae; canis familiaris; domestication; felidae; felis catus; reduced major axis regression; sexual size dimorphism
• ISSN: 2500-0462; 2500-3259
• DOI: 10.18699/VJ17.263

The domestication syndrome already recognized by Darwin shows that domesticated species acquire a number of novel morphological, physiological and behavioral characteristics not present in their wild ancestors. Because body size and sexual size dimorphism (SSD) are essential characteristics of species that affect most aspects of their life histories, we studied the effects of domestication on body size and SSD in domestic dogs and cats in comparison with their wild relatives: the Canidae and Felidae, respectively, and also analyzed the occurrence of Rensch’s rule within both domestic species. We studied maximum body mass and maximum height at withers of 64 and 89 domestic dog breeds respectively, and maximum body mass of 37 domestic cat breeds as well as body mass data for 36 wild Canidae and 36 wild Felidae from our previous studies. Our results have shown that domestic dogs maintain a level and range of body mass which largely exceeds that of the Canidae as a whole while maintaining a similar degree and range of SSD. On the contrary, domestic cats show a much reduced body mass range within the limits of their ancestor species while showing comparable levels of SSD as shown by the Felidae. Regarding Rensch’s rule, both Reduced Major Axis and Ordinary Least Squares regressions showed that both domestic species present a scaling of male and female body sizes consistent with Rensch’s rule while their wild relatives do not. We discuss these findings in the light of present knowledge about the domestication of Canis familiaris and Felis catus.