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Research article - Peer-reviewed, 2023

Aggression and spatial positioning of kin and non-kin fish in social groups

Bose, Aneesh P. H.; Dabernig-Heinz, Johanna; Oberkofler, Jan; Koch, Lukas; Grimm, Jacqueline; Sefc, Kristina M.; Jordan, Alex


Group-living animals must share space and resources with group mates, who can be either kin or non-kin, and it is often unclear how competitive or cooperative group members should be. In a group-living cichlid, we show that co-habiting females are less aggressive to their female kin (relative to non-kin) despite living at equivalent distances to one another. This pattern was not detected among co-habiting males, revealing that kin-directed social behavior can differ between the sexes.Group-living animals are faced with the challenge of sharing space and local resources amongst group members who may be either relatives or non-relatives. Individuals may reduce the inclusive fitness costs they incur from competing with relatives by either reducing their levels of aggression toward kin, or by maintaining physical separation between kin. In this field study, we used the group-living cichlid Neolamprologus multifasciatus to examine whether within-group aggression is reduced among group members that are kin, and whether kin occupy different regions of their group's territory to reduce kin competition over space and local resources. We determined the kinship relationships among cohabiting adults via microsatellite genotyping and then combined these with spatial and behavioral analyses of groups in the wild. We found that aggressive contests between group members declined in frequency with spatial separation between their shelters. Female kin did not engage in aggressive contests with one another, whereas non-kin females did, despite the fact these females lived at similar distances from one another on their groups' territories. Contests within male-male and male-female dyads did not clearly correlate with kinship. Non-kin male-male and male-female dyads lived at more variable distances from one another on their territories than their corresponding kin dyads. Together, our study indicates that contests among group members can be mediated by relatedness in a sex-dependent manner. We also suggest that spatial relationships can play an important role in determining the extent to which group members compete with one another.


cichlid; contest behavior; genetic relatedness; group living; kin discrimination; kin selection; sex differences; within-group competition

Published in

Behavioral Ecology
2023, Volume: 34, number: 4, pages: 673-681

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    Behavioral Sciences Biology

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