Pf. Kukuk et al., MUTUALISTIC BENEFITS GENERATE AN UNEQUAL DISTRIBUTION OF RISKY ACTIVITIES AMONG UNRELATED GROUP MEMBERS, Naturwissenschaften, 85(9), 1998, pp. 445-449
Recent studies provide a new challenge to the adequacy of theories con
cerning the evolution of cooperation among nonrelatives: some individu
als perform high-risk activities while others do not. We examined a co
mmunal hymenopteran species, Lasioglossum (Chilalictus) hemichalceum,
to determine why group members engaged in demonstrably risky activitie
s (foraging) tolerate the selfish behavior (remaining in the nest) of
unrelated nestmates. Experimental removal of adult females indicated t
hat their presence is required for the protection of brood from ant pr
edators. Nonforagers ensure the continued presence of adults in the ne
st if the risk-taking foragers die, thereby safeguarding the survival
of forager offspring. This results in an unequal distribution of risky
activities within social groups in which avoidance of risky activitie
s by some group members is ultimately beneficial to risk takers.