A study suggests a mechanism by which long-tailed tits avoid incest. Many animal species avoid inbreeding, which can be detrimental to health, through mechanisms such as sex-biased dispersal, in which members of one sex leave their native site to breed. However, cooperative species with limited dispersal could encounter kin as potential mates, presenting a quandary. Amy Leedale and colleagues examined how long-tailed tits (Aegithalos caudatus), a species in which kin-directed cooperation is common and dispersal is constrained, avoid inbreeding when the birds pair off monogamously each spring. Analysis of 17 genetic markers and four fitness-related life-history traits, including lifetime reproductive success and fraction of eggs hatched in a female's first clutch, revealed that inbreeding is harmful to the birds' fitness. Genetic relatedness analysis combined with mate choice models indicated that the birds avoid close kin while pairing. Long-tailed tits use learned vocal cues to preferentially aid kin, and the authors found that the tits' churr call, a short-range contact call akin to an individual signature, likely helps the birds avoid incest. Males and females within breeding pairs had more distinct churr calls than opposite-sex first-order kin within pairing range; the vocal distinction did not extend to second-order kin or nonkin. Similarities in learned vocal cues may stem from the close association of first-order kin--parents, offspring, and siblings--during rearing, when calls are learned; second-order kin and nonkin are usually reared apart. According to the authors, the study uncovers a potential mechanism by which long-tailed tits avoid incest.
Article #19-18726: "Cost, risk, and avoidance of inbreeding in a cooperatively breeding bird," by Amy Leedale et al.
MEDIA CONTACT: Amy Leedale, University of Cambridge, UNITED KINGDOM; e-mail: ael57@cam.ac.uk
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Proceedings of the National Academy of Sciences