A1 Refereed original research article in a scientific journal
Are elder siblings helpers or competitors? Antagonistic fitness effects of sibling interactions in humans
Authors: Nitsch A, Faurie C, Lummaa V
Publisher: ROYAL SOC
Publication year: 2013
Journal: Proceedings of the Royal Society B: Biological Sciences
Journal name in source: PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
Journal acronym: P ROY SOC B-BIOL SCI
Article number: ARTN 20122313
Volume: 280
Issue: 1750
Number of pages: 9
ISSN: 0962-8452
DOI: https://doi.org/10.1098/rspb.2012.2313
Abstract
Determining the fitness consequences of sibling interactions is pivotal for understanding the evolution of family living, but studies investigating them across lifetime are lacking. We used a large demographic dataset on preindustrial humans from Finland to study the effect of elder siblings on key life-history traits. The presence of elder siblings improved the chances of younger siblings surviving to sexual maturity, suggesting that despite a competition for parental resources, they may help rearing their younger siblings. After reaching sexual maturity however, same-sex elder siblings' presence was associated with reduced reproductive success in the focal individual, indicating the existence of competition among same-sex siblings. Overall, lifetime fitness was reduced by same-sex elder siblings' presence and increased by opposite-sex elder siblings' presence. Our study shows opposite effects of sibling interactions depending on the life-history stage, and highlights the need for using long-term fitness measures to understand the selection pressures acting on sibling interactions.
Determining the fitness consequences of sibling interactions is pivotal for understanding the evolution of family living, but studies investigating them across lifetime are lacking. We used a large demographic dataset on preindustrial humans from Finland to study the effect of elder siblings on key life-history traits. The presence of elder siblings improved the chances of younger siblings surviving to sexual maturity, suggesting that despite a competition for parental resources, they may help rearing their younger siblings. After reaching sexual maturity however, same-sex elder siblings' presence was associated with reduced reproductive success in the focal individual, indicating the existence of competition among same-sex siblings. Overall, lifetime fitness was reduced by same-sex elder siblings' presence and increased by opposite-sex elder siblings' presence. Our study shows opposite effects of sibling interactions depending on the life-history stage, and highlights the need for using long-term fitness measures to understand the selection pressures acting on sibling interactions.
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