Il ruolo delle marcature nel sifaka diadema, Propithecus diadema

Group living primates use different communication channels, including olfaction, to engage social interaction with conspecifics. Among lemurs, the diademed sifakas (Propithecus diadema) which lives in dense vegetation with limited visibility and exhibits a complex social system, uses scent-marking to communicate within and between groups and may use chemical signals to defend territory and resources. However, very little is known of the behavioural patterns related to scent-marking in this species. We investigated the effects of socio-sexual variables (sex and rank) and reproductive schedule (season) on the occurrence of scent-marking. Moreover, we investigated the spatial distribution of markings in relation to the intensity of home-range use, to test the implication of marking in territorial defense, using spatial statystic in ArcGIS. The results showed an intersexual difference in the scent-marking occurrence, where males marked and over-marked higher than females. However, female depositions were more frequently targeted by over-marks than those of males. Besides, dominant individuals performed marking and over-marking significantly more than subordinates, as a possible strategy to maintain dominance status that can be crucial for mating priority. Furthermore, the scent-marking and sex-specific sternal marking, in particular, were highly deposited during the mating season, suggesting the effect of sexual selection. Our finding supports the hypothesis that marking may be used by the individuals of both sexes to advertise their presence within the home range, but in females it may additionally serve to enhance male-male competition for mate. Also, over-marking occurrence was highest in dominant males, as a possible form of warning for other male competitors. Furthermore, the distribution of marking hotspots was related to the intensity of home-range use; the majority of significant hotspots lied inside the most used areas inside the home-range. In conclusion, P. diadema's scent-marking is crucial for coordinating socio-sexual interaction among conspecifics and shows more complex patterns than previously thought. Moreover, scent-marking in this species is involved in territorial defense, supporting the multi-purpose function in Primates.