Impact of social relationships on adult trill calls in grey mouse lemurs (Microcebus murinus)

Social accommodation constitutes a special form of vocal learning where individuals converge or diverge the structure of their call types based on social experience. This phenomenon has mainly been described in pair-bonded and group-living species, as it is suggested that social accommodation is dependent on the social lifestyle of the sender. Therefore, we investigated social accommodation in the grey mouse lemur, a promising primate model, which combines two social lifestyles: females form
long-term sleeping groups, while males live solitarily. We used 482 trill calls of 36 individuals (22 females, 14 males) from our captive breeding colony, of which temporal and spectral acoustic parameters were measured. The obtained data was then used in a nested pDFA to investigate whether trills can be classified by sex while DFAs were conducted separately for both sexes to test whether individual vocal signatures in the trills of both sexes exist. To investigate the impact of genetic relatedness, social contact and body weight on individual vocal signatures, LMEs and Mantel tests were
performed for each sex separately. We found that the trills of both sexes differed significantly from each other, with individual vocal signatures present in the trills of both sexes. For the females, the trills became more similar the more time they spent sharing a cage, while for the males the trills were more similar between genetically related individuals. However, between males which had socialised with each other, the trills became more different the more time they spent with each other. Our results
suggest that grey mouse lemurs show the capacity for social accommodation, with females converging their calls to sleeping group partners to signal social affinity, while males either do not adapt or diverge their calls to those of their social partners to pronounce differences between individuals.