title: The fitness consequences of kin-biased dispersal in a cooperatively breeding bird.
abstract: Cooperative alliances among kin may not only lead to indirect fitness benefits for group-living species, but can also provide direct benefits through access to mates or higher social rank. However, the immigrant sex in most species loses any potential benefits of living with kin unless immigrants disperse together or recruit relatives into the group in subsequent years. To look for evidence of small subgroups of related immigrants within social groups (kin substructure), we used microsatellites to assess relatedness between immigrant females of the cooperatively breeding superb starling, Lamprotornis superbus. We determined how timing of immigration led to kin subgroup formation and if being part of one influenced female fitness. Although mean relatedness in groups was higher for males than females, 26% of immigrant females were part of a kin subgroup with a sister. These immigrant sibships formed through kin recruitment across years more often than through coalitions immigrating together in the same year. Furthermore, females were more likely to breed when part of a kin subgroup than when alone, suggesting that female siblings form alliances that may positively influence their fitness. Ultimately, kin substructure should be considered when determining the role of relatedness in the evolution of animal societies.
authors.affiliation: Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, NY 10027, USA.
authors.forename: Lea
authors.initials: L
authors.lastname: Pollack
authors.affiliation: Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue, New York, NY 10027, USA Department of Ornithology and Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA dr2497@columbia.edu.
authors.forename: Dustin R
authors.identifier: http://orcid.org/0000-0002-4999-3723
authors.initials: DR
authors.lastname: Rubenstein
mesh_terms: D025041:Animal Migration; D000818:Animals; D003299:Cooperative Behavior; D005260:Female; D008297:Male; D018895:Microsatellite Repeats; D009425:Nesting Behavior; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal; D012919:Social Behavior; D046749:Starlings / Q000235:genetics / Q000502:physiology*
keywords: cooperative breeding; kin selection; relatedness; sex-biased dispersal