title: Individual and population-level sex-dependent lateralization in yellow-legged gull (Larus michahellis) chicks.
abstract: Behavioral lateralization at the population level is widespread across vertebrates, with considerable variation among species. However, evidence for individual-level and sex-dependent lateralization is sparse and inconsistent in fish, reptiles and birds. In addition, covariation of lateralization with position in the laying sequence, which is expected because the concentration of maternal egg hormones varies with laying order, has never been investigated. We analyzed lateralization of yellow-legged gull (Larus michahellis) chicks in reverting from supine to prone posture ('RTP' response) and in pecking at a dummy parental bill to solicit food provisioning ('begging' response). Chicks were lateralized both at the population and at the individual level in the RTP response and at the individual level in begging. Lateralization in the RTP was sex-dependent, as females showed a leftward preference. Lateralization in either motor task was not correlated within individuals. Lateralization did not differ among families, suggesting little additive genetic variation. Lateral preference in begging response varied according to laying order and matched variation in egg androgens concentration. Our study confirms previous findings on population-level lateralization and adds to the scant information on individual-level and heritable variation in lateralization in birds. Moreover, it hints at epigenetic components in lateralization depending on maternal effects.
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, I-20133 Milan, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Romano
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, I-20133 Milan, Italy. Electronic address: marco.parolini@unimi.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Parolini
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, I-20133 Milan, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Caprioli
authors.affiliation: Research and Conservation Department, Parco Naturaviva, Verona, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Spiezio
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, I-20133 Milan, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Rubolini
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, I-20133 Milan, Italy. Electronic address: nicola.saino@unimi.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Saino
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D046091:Charadriiformes / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D012737:Sex Factors
keywords: Begging behavior; Heritability; Larus michahellis; Lateralization; Laying order; Maternal effects; Sex; Stress