Females do it better. Individual recognition experiments reveal sexual dimorphism in Lemur catta (Linnaeus 1758) olfactory motivation and territorial defence

In this paper, we aim at demonstrating individual recognition of female genital marking in Lemur catta. By gas chromatography and behavioural trials we verified the occurrence of the three components of recognition systems. We showed that each female has a unique chemical signature (expression component), and males and females perceive female individuality (perception component). To verify the presence of the action component (the last component of recognition systems), we designed a bioassay based on territorial competition to verify the functional response to female odours. Only females identified other females on the basis of their scents. The lack of a territorial functional response by males to female secretions may not indicate a male inability to identify females by their scents. In fact, sexual dimorphism in motivation and territorial defence may explain the response by males in the functional experiment. Actually, game theory predicts that males defend their own territories more vigorously against males compared with females. Therefore, the result of individual recognition bioassays of female odours may open interesting scenarios in the evaluation of the territorial defence investment across the different sex combinations.