title: Male rhesus macaques use vocalizations to distinguish female maternal, but not paternal, kin from non-kin.
abstract: Recognizing close kin and adjusting one's behavior accordingly (i.e., favor kin in social interactions, but avoid mating with them) would be an important skill that can increase an animals' inclusive fitness. Previous studies showed that philopatric female rhesus macaques (Macaca mulatta) bias their social behavior toward maternal and paternal kin. Benefits gained from selecting kin should, however, not only apply to the philopatric sex, for which the enduring spatial proximity facilitates kin discrimination. Given that dispersal is costly, the dispersing sex may benefit from migrating together with their kin or into groups containing kin. In male rhesus macaques, natal migrants bias their spatial proximity toward familiar male kin rather than familiar non-kin. Here, we set up playback experiments to test if males use the acoustic modality to discriminate familiar female kin from non-kin in a non-sexual context. Males responded differently to the presentation of "coo" calls of related and unrelated females, with their reaction depending on the interaction between kin-line (maternal vs paternal kin) and degree of relatedness (r= 0.5, 0.25). Specifically, males were more likely to respond to close kin compared to more distant kin or unrelated females, with this effect being significant in the maternal, but not paternal kin-line. The present study adds to our knowledge of kin recognition abilities of the dispersing sex, suggesting that male rhesus macaques are also able to identify kin using the acoustic modality. We discuss that the probability of response might be affected by the potential benefit of the social partner.
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany ; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, Leipzig, Germany ; Cognitive Neuroscience Laboratory, German Primate Center, Göttingen, Germany ; Leibniz-Science Campus Primate Cognition, German Primate Center and Georg-August-University, Göttingen, Germany.
authors.forename: Dana
authors.initials: D
authors.lastname: Pfefferle
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany ; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, Leipzig, Germany ; Caribbean Primate Research Center-Cayo Santiago, University of Puerto Rico, Puerto Rico, USA.
authors.forename: Angelina V
authors.initials: AV
authors.lastname: Ruiz-Lambides
authors.affiliation: Junior Research Group of Primate Kin Selection, Department of Primatology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany ; Behavioural Ecology Research Group, Institute of Biology, University of Leipzig, Leipzig, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Widdig
keywords: Degree of relatedness; Dispersing sex; Male kin recognition; Maternal vs paternal kin; Playback experiment; Vocalization