TY - JOUR
T1 - Stable social relationships between unrelated females increase individual fitness in a cooperative bird
AU - Riehl, Christina Pauline
AU - Strong, Meghan J.
N1 - Funding Information:
Ethics. The research in this study was approved by the Institutional Animal Care and Use Committee of the Smithsonian Tropical Research Institute. Genetic samples were collected and exported with approval from the Ministerio de Ambiente de Panamá, and imported to the USA with approval from the US Department of Agriculture. Data accessibility. The data generated and analysed during this study is available in the Dryad Digital Repository (http://dx.doi.org/10. 5061/dryad.46tj577 [56]). Authors’ contributions. C.R. conceived the study and conducted statistical analyses. C.R. and M.J.S. collected data and conducted genetic analyses. C.R. wrote the paper with input from M.J.S. Both authors contributed to interpretation of data and presentation of results. Competing interests. The authors declare no competing interests. Funding. The long-term ani field monitoring programme was funded by the Smithsonian Tropical Research Institute, Princeton University and the Princeton Environmental Institute at Princeton University.
Publisher Copyright:
© 2018 The Author(s) Published by the Royal Society. All rights reserved.
PY - 2018/4/11
Y1 - 2018/4/11
N2 - Social animals often form long-lasting relationships with fellow group members, usually with close kin. In primates, strong social bonds have been associated with increased longevity, offspring survival and reproductive success. However, little is known about the fitness effects of social bonds between non-kin, especially outside of mammals. In this study, we use long-term field research on a cooperatively breeding bird, the greater ani (Crotophaga major), to ask whether adult females benefit by remaining in long-term associations with unrelated, co-breeding females. We find that females that have previously nested together synchronize their reproduction more rapidly than those nesting with unfamiliar partners, which leads to lower competition and higher fledging success. Importantly, although previous experience with a co-breeding female influenced reproductive synchrony, the degree of reproductive synchrony did not influence whether co-breeding females remained together in subsequent years, ruling out the alternate hypothesis that highly synchronized females are simply more likely to remain together. These results indicate that switching groups is costly to females, and that social familiarity improves reproductive coordination. Stable social relationships therefore have significant fitness consequences for cooperatively nesting female birds, suggesting that direct benefits alone may favour the evolution of associations between non-relatives and contribute to long-term group stability.
AB - Social animals often form long-lasting relationships with fellow group members, usually with close kin. In primates, strong social bonds have been associated with increased longevity, offspring survival and reproductive success. However, little is known about the fitness effects of social bonds between non-kin, especially outside of mammals. In this study, we use long-term field research on a cooperatively breeding bird, the greater ani (Crotophaga major), to ask whether adult females benefit by remaining in long-term associations with unrelated, co-breeding females. We find that females that have previously nested together synchronize their reproduction more rapidly than those nesting with unfamiliar partners, which leads to lower competition and higher fledging success. Importantly, although previous experience with a co-breeding female influenced reproductive synchrony, the degree of reproductive synchrony did not influence whether co-breeding females remained together in subsequent years, ruling out the alternate hypothesis that highly synchronized females are simply more likely to remain together. These results indicate that switching groups is costly to females, and that social familiarity improves reproductive coordination. Stable social relationships therefore have significant fitness consequences for cooperatively nesting female birds, suggesting that direct benefits alone may favour the evolution of associations between non-relatives and contribute to long-term group stability.
KW - Cooperation
KW - Cooperative breeding
KW - Crotophaga major
KW - Group stability
KW - Social affiliation
KW - Social bond
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U2 - 10.1098/rspb.2018.0130
DO - 10.1098/rspb.2018.0130
M3 - Article
C2 - 29643212
AN - SCOPUS:85045333321
SN - 0962-8452
VL - 285
JO - Proceedings of the Royal Society B: Biological Sciences
JF - Proceedings of the Royal Society B: Biological Sciences
IS - 1876
M1 - 20180130
ER -