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Altruism can evolve when relatedness is low: evidence from bacteria committing suicide upon phage infection


Refardt, D; Bergmiller, T; Kümmerli, Rolf (2013). Altruism can evolve when relatedness is low: evidence from bacteria committing suicide upon phage infection. Proceedings of the Royal Society of London, Series B: Biological Sciences, 280(1759):20123035.

Abstract

High relatedness among interacting individuals has generally been considered a precondition for the evolution of altruism. However, kin-selection theory also predicts the evolution of altruism when relatedness is low, as long as the cost of the altruistic act is minor compared with its benefit. Here, we demonstrate evidence for a low-cost altruistic act in bacteria. We investigated Escherichia coli responding to the attack of an obligately lytic phage by committing suicide in order to prevent parasite transmission to nearby relatives. We found that bacterial suicide provides large benefits to survivors at marginal costs to committers. The cost of suicide was low, because infected cells are moribund, rapidly dying upon phage infection,such that no more opportunity for reproduction remains. As a consequence of its marginal cost, host suicide was selectively favoured even when relatedness between committers and survivors approached zero. Altogether, our findings demonstrate that low-cost suicide can evolve with ease, represents an effective host-defence strategy, and seems to be widespread among microbes. Moreover, low-cost suicide might also occur in higher organisms as exemplified by infected social insect workers leaving the colony to die in isolation.

Abstract

High relatedness among interacting individuals has generally been considered a precondition for the evolution of altruism. However, kin-selection theory also predicts the evolution of altruism when relatedness is low, as long as the cost of the altruistic act is minor compared with its benefit. Here, we demonstrate evidence for a low-cost altruistic act in bacteria. We investigated Escherichia coli responding to the attack of an obligately lytic phage by committing suicide in order to prevent parasite transmission to nearby relatives. We found that bacterial suicide provides large benefits to survivors at marginal costs to committers. The cost of suicide was low, because infected cells are moribund, rapidly dying upon phage infection,such that no more opportunity for reproduction remains. As a consequence of its marginal cost, host suicide was selectively favoured even when relatedness between committers and survivors approached zero. Altogether, our findings demonstrate that low-cost suicide can evolve with ease, represents an effective host-defence strategy, and seems to be widespread among microbes. Moreover, low-cost suicide might also occur in higher organisms as exemplified by infected social insect workers leaving the colony to die in isolation.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Plant and Microbial Biology
Dewey Decimal Classification:580 Plants (Botany)
Language:English
Date:2013
Deposited On:03 Jan 2014 12:20
Last Modified:18 Apr 2018 11:44
Publisher:Royal Society Publishing
ISSN:0962-8452
Funders:SNSF, ETH Zurich, Marie Curie Reintegration grant
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1098/rspb.2012.3035
Project Information:
  • : FunderFP7
  • : Grant ID256435
  • : Project TitlePA_EXP_EVOL - Siderophore production in the human pathogen Pseudomonas aeruginosa: a model trait to study the evolution of cooperation and virulence
  • : FunderSNSF
  • : Grant ID
  • : Project TitleSNSF
  • : Funder
  • : Grant ID
  • : Project TitleETH Zurich
  • : Funder
  • : Grant ID
  • : Project TitleMarie Curie Reintegration grant

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