471: Learned kin recognition cues in a social bird : Nature
In long-tailed tits, all adults attempt to breed independently in pairs each year, but most nests fail due to depredation13, 14. Failed breeders often re-nest, but later in the season may instead become helpers14; this switch from re-nesting to helping corresponds with a seasonal change in the potential fitness benefits of each strategy15. No significant direct fitness benefits of helping have been found, but helpers preferentially care for close relatives16 and accrue indirect fitness benefits by increasing brood productivity14, 15; this kin-selected benefit represents a substantial component of inclusive fitness and is the sole source of fitness for many individuals17. Thus, helping is beneficial to both helpers and recipients, and selection should favour kin recognition6, 8. Kin-biased helping occurs in the absence of reliable spatial cues to kinship16, and a previous study suggested that long-tailed tits can discriminate between the vocalizations of close relatives and non-relatives18. Here, we describe an experiment that determines the characteristics of contact calls used in discrimination, and a second experiment that investigates the acquisition of these recognition cues.
Fitness benefits, and kin selection are parts of evolutionary hypotheses. The characteristics used and the methods of acquisition will be under heavy selection, since cheating will be good for a cheater, but horrible for the cheated.