Altruism and natural selection in a variable environment
(2024) In Proceedings of the National Academy of Sciences of the United States of America 121(38).- Abstract
Hamilton’s rule provides the cornerstone for our understanding of the evolution of all forms of social behavior, from altruism to spite, across all organisms, from viruses to humans. In contrast to the standard prediction from Hamilton’s rule, recent studies have suggested that altruistic helping can be favored even if it does not benefit relatives, as long as it decreases the environmentally induced variance of their reproductive success (“altruistic bet-hedging”). However, previous predictions both rely on an approximation and focus on variance-reducing helping behaviors. We derived a version of Hamilton’s rule that fully captures environmental variability. This shows that decreasing (or increasing) the variance in the absolute... (More)
Hamilton’s rule provides the cornerstone for our understanding of the evolution of all forms of social behavior, from altruism to spite, across all organisms, from viruses to humans. In contrast to the standard prediction from Hamilton’s rule, recent studies have suggested that altruistic helping can be favored even if it does not benefit relatives, as long as it decreases the environmentally induced variance of their reproductive success (“altruistic bet-hedging”). However, previous predictions both rely on an approximation and focus on variance-reducing helping behaviors. We derived a version of Hamilton’s rule that fully captures environmental variability. This shows that decreasing (or increasing) the variance in the absolute reproductive success of relatives does not have a consistent effect—it can either favor or disfavor the evolution of helping. We then empirically quantified the effect of helping on the variance in reproductive success across 15 species of cooperatively breeding birds. We found that a) helping did not consistently decrease the variance of reproductive success and often increased it, and b) the mean benefits of helping across environments consistently outweighed other variability components of reproductive success. Altogether, our theoretical and empirical results suggest that the effects of helping on the variability components of reproductive success have not played a consistent or strong role in favoring helping.
(Less)
- author
- dos Santos, Miguel ; Downing, Philip A. LU ; Griffin, Ashleigh S. ; Cornwallis, Charlie K. LU and West, Stuart A.
- organization
- publishing date
- 2024-09
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- social evolution, | bet-hedging, | cooperative breeding, | kin selection
- in
- Proceedings of the National Academy of Sciences of the United States of America
- volume
- 121
- issue
- 38
- article number
- e2402974121
- publisher
- National Academy of Sciences
- external identifiers
-
- scopus:85203755942
- pmid:39255001
- ISSN
- 0027-8424
- DOI
- 10.1073/pnas.2402974121
- language
- English
- LU publication?
- yes
- id
- dbd394fd-e310-4581-bab8-83c9325a8d72
- date added to LUP
- 2024-11-22 12:14:42
- date last changed
- 2025-07-05 07:56:30
@article{dbd394fd-e310-4581-bab8-83c9325a8d72,
abstract = {{<p>Hamilton’s rule provides the cornerstone for our understanding of the evolution of all forms of social behavior, from altruism to spite, across all organisms, from viruses to humans. In contrast to the standard prediction from Hamilton’s rule, recent studies have suggested that altruistic helping can be favored even if it does not benefit relatives, as long as it decreases the environmentally induced variance of their reproductive success (“altruistic bet-hedging”). However, previous predictions both rely on an approximation and focus on variance-reducing helping behaviors. We derived a version of Hamilton’s rule that fully captures environmental variability. This shows that decreasing (or increasing) the variance in the absolute reproductive success of relatives does not have a consistent effect—it can either favor or disfavor the evolution of helping. We then empirically quantified the effect of helping on the variance in reproductive success across 15 species of cooperatively breeding birds. We found that a) helping did not consistently decrease the variance of reproductive success and often increased it, and b) the mean benefits of helping across environments consistently outweighed other variability components of reproductive success. Altogether, our theoretical and empirical results suggest that the effects of helping on the variability components of reproductive success have not played a consistent or strong role in favoring helping.</p>}},
author = {{dos Santos, Miguel and Downing, Philip A. and Griffin, Ashleigh S. and Cornwallis, Charlie K. and West, Stuart A.}},
issn = {{0027-8424}},
keywords = {{social evolution; | bet-hedging; | cooperative breeding; | kin selection}},
language = {{eng}},
number = {{38}},
publisher = {{National Academy of Sciences}},
series = {{Proceedings of the National Academy of Sciences of the United States of America}},
title = {{Altruism and natural selection in a variable environment}},
url = {{http://dx.doi.org/10.1073/pnas.2402974121}},
doi = {{10.1073/pnas.2402974121}},
volume = {{121}},
year = {{2024}},
}