Dominance relationships in lemurs: more than just female dominance and hierarchy linearity

The determination of hierarchical relationships is a controversial issue in primate sociobiology, due to non homogeneity in the methodology used for hierarchy assessment. Here we investigated the dominance style of three sympatric lemur species, Lemur catta (two groups), Propithecus verreauxi (two groups), and introduced Eulemur fulvus x collaris (one group), in the Berenty forest, Madagascar. Data were collected in the periods November 2006-February 2007 (wet season) and March-July 2008 (dry season), via all occurrences animal sampling. Ad-libitum we checked for group dispersion (individuals spaced >=20m) and used it for a post-hoc evaluation of the cohesion level around the dominant. Based on aggression sociomatrices, we assessed hierarchy via both binary dyadic relationships and normalized David's scores. We assessed linearity also via supplant sociomatrices. Although all species shared female dominance and linear hierarchy, Lemur catta was the most despotic, showing a highly cohesive, steep and formalized hierarchy. Eulemur fulvus showed the shallowest hierarchy. Propithecus verreauxi showed a cohesive hierarchy as Lemur catta but also a scarcely formalized hierarchy as Eulemur fulvus. Overall, our results indicate that each lemur has a species-specific, and even group-specific profile, reflecting different despotism levels.