DOI: 10.5061/dryad.b1q2n
title: Data from: Altruism can evolve when relatedness is low: evidence from bacteria committing suicide upon phage infection

description: 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 to 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.
description: readme.txtContains descriptions of all data files.120308b_2.pdaFile: 120308b_2.pda Format: SoftMax Pro 5.42.1.0 (Molecular Devices, Sunnyvale, CA) Contents: Measurements of optical density of bacterial cultures. Rows A-D contain cultures of E. coli lambda, rows E-H contain cultures of E. coli HK97. Columns 1 and 2 contain uninfected cultures. Columns 3-11 contain cultures that were infected with 5x10^0 - 5x10^8 pfu of phage T4rII. Column 12 contains blanks (medium only).120308b_2.txtFile: 120308b_2.txt Format: text Contents Measurements of optical density of bacterial cultures Note: Same data as in file 120308b_2.pdafigure1_r_script.rFile: figure1_r_script.r Format: r source file Contents: reads in all growth data, calculates doubling times, calculates statistics, plots figure 1 to pdf Note: requires package nlstoolsintrinsic_costs.zipFiles: intrinsic_costs.zip (contains files well.XXX (XXX are numbers from 001 to 096)) Format: ZIP archive (contents are flow cytometry data files FCS 2.0) Contents: Flow cytometry analyses of bacterial cultures. Samples were excited at a wavelength of 488 nm, while emission was detected at 510 nm (GFP) and 560 nm (DsRed).120524_exp390.csvFile: 120524_exp390.csv Format: text (comma separated values) Contents: Data obtained from the analysis of all flow cytometry data files in intrinsic_costs.zip using WEASEL 3.0.1. Files also contains information about the identity of every sample.intrinsic_costs_r_script.rFile: intrinsic_costs_r_script.r Format: r source file Contents: reads in all flow cytometry data and calculates statisticsintrinsic_costs_r_script.R120524_1.pdaFile: 120524_1.pda Format: SoftMax Pro 5.42.1.0 (Molecular Devices, Sunnyvale, CA) Contents: Measurements of optical density of bacterial cultures. Cultures in rows A, C, E, and G contain treatments without phage T4rII, cultures in rows B, D, F, and H contain treatments with phage T4rII. E. coli lambda was labelled with pDsRed in columns 1, 3, 5, 7, 9, and 11. E. coli lambda was labelled with pGFP in columns 2, 4, 6, 8, 10, and 12. The initial frequency of E. coli lambda was 99.9% in cultures in columns 1 and 2, 99% in cultures in columns 3 and 4, 95% in cultures in columns 5 and 6, 90% in cultures in columns 7 and 8, 50% in cultures in columns 9 and 10, and 10% in cultures in columns 11 and 12.120524_1.txtFile: 120524_1.txt Format: text Contents Measurements of optical density of bacterial cultures Note: Same data as in file 120524_1.pdafigure2.zipFiles: figure2.zip (contains files well.XXX (XXX are numbers from 079 to 108 and from 301 to 396)) Format: ZIP archive (contains flow cytometry data files FCS 2.0) Contents: Flow cytometry analyses of bacterial cultures. Samples were excited at a wavelength of 488 nm, while emission was detected at 510 nm (GFP) and 560 nm (DsRed).120525_exp391.csvFile: 120525_exp391.csv Format: text (comma separated values) Contents: Data obtained from the analysis of flow cytometry data files well.301 - well.396 using WEASEL 3.0.1. File also contains information about the identity of every sample. Data are from samples taken after the competition experiment.120524_97-108.csvFile: 120524_97-108.csv Format: text (comma separated values) Contents: Data obtained from the analysis of flow cytometry data files well.079 - well.108 using WEASEL 3.0.1. File also contains information about the identity of every sample. Data are from samples prior to the competition experiment and are used to obtain the initial frequencies of the competitors as shown on the x-axis of the inset of figure 2 and on the right side of figure 2.figure2_r_script.RFile: figure2_r_script.r Format: r source file Contents: reads in all growth data, reads in all flow cytometry data, calculates statistics, plots figure 2 to pdf Note: requires package dichromatfigure3.zipFiles: figure3.zip (contains files well.XXX (XXX are numbers from 001 - 096, from 101 to 196, and from 201 to 204)) Format: ZIP archive (contains flow cytometry data file FCS 2.0) Contents: Flow cytometry analyses of bacterial cultures. Samples were excited at a wavelength of 488 nm, while emission was detected at 510 nm (GFP) and 560 nm (DsRed).120525_exp392b.csvFile: 120525_exp392b.csv Format: text (comma separated values) Contents: Data obtained from the analysis of flow cytometry data files well.101 - well.196 and well.201 - well.204 using WEASEL 3.0.1. File also contains information about the identity of every sample. Data are use to produce figure 3a.120525_exp392a.csvFile: 120525_exp392a.csv Format: text (comma separated values) Contents: Data obtained from the analysis of flow cytometry data files well.001 - well.096 and well.201 - well.202 using WEASEL 3.0.1. File also contains information about the identity of every sample. Data are used to produce figure 3b.figure3_r_script.rFile: figure3_r_script.r Format: r source file Contents: reads in all growth data, reads in all flow cytometry data, calculates statistics, plots figure 3a and 3b to pdf Note: requires package dichromatfigure3_r_script.R