Cumulative effects of mutation and selection on susceptibility to bacterial pathogens in Caenorhabditis elegans
Data files
Oct 16, 2025 version files 678.64 KB
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README.md
3.67 KB
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Supplemental_Table_S1.xlsx
204.37 KB
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Supplemental_Tables_S2-S7.xlsx
470.60 KB
Abstract
Understanding the evolutionary and genetic underpinnings of susceptibility to pathogens is of fundamental importance across a wide swathe of biology. Much theoretical and empirical effort has focused on genetic variants of large effect, but pathogen susceptibility often appears to be a polygenic complex trait. Here we investigate the quantitative genetics of survival over 120 hours of exposure ("susceptibility") of C. elegans to three bacterial species of varying virulence, along with a fourth strain, the OP50 strain of E. coli, the standard laboratory food for C. elegans. We compare the genetic (co)variance input by spontaneous mutations accumulated under minimal selection to the standing genetic (co)variance in a set of 47 wild isolates. Three conclusions emerge. First, mutations increase susceptibility to pathogens. Second, susceptibility to pathogens is uncorrelated with fitness in the absence of pathogens. Third, with the possible exception of S. aureus, pathogen susceptibility is clearly under purifying directional selection of magnitude roughly similar to that of competitive fitness in the MA conditions. The results provide no evidence for fitness tradeoffs between pathogen susceptibility and fitness in the absence of pathogens.
Dataset DOI: 10.5061/dryad.5qfttdzjs
Description of the data and file structure
The purpose of the experiment was to estimate the cumulative effects of spontaneous mutations on the susceptibility of C. elegans to bacterial pathogens. The experimental methods are described in detail in the accompanying manuscript. The two data files (Supplemental_Table_S1.xlsx and Supplemental Tables S2-S7.xlsx) consist of Excel worksheets. Each data sheet has its own accompanying "Readme" document on the following worksheet. The missing data from an empty cell is changed to a "."
Files and variables
File: Supplemental_Tables_S2-S7.xlsx
Description: An Excel file containing Supplemental Tables S2 through S7 from the accompanying article. Each data worksheet, titled "TSx..." (where the x is the number of the table) has its accompanying explanatory "Readme" document following the data worksheet.
Variables
- See the relevant "Readme" worksheet for each table.
File: Supplemental_Table_S1.xlsx
Description: An Excel file containing Supplemental Table S1, contains the information about "going to backup" (defined in the Methods section of the text). Worksheet "N2" contains data for the N2 lines, worksheet "PB306" contains data for the PB306 lines. The worksheet titled "Readme" contains the explanatory information.
Description:
The two preceding worksheets show the the outcome of the transfer of a worm in each MA line at each generation. In both strains, transfers occurred at four-day intervals. Rows are MA lines, columns are transfers at a given generation of MA (1→Gmax). A cell with a "." indicates a successful transfer. A cell with a "b" (for "backup") indicates that the worm was either dead, missing, or obviously sterile, so a worm was taken from the backup plate from the preceding generation (see Methods for details). A cell with an "h" (for "holdover") indicates that either the parent worm had not reproduced but was gravid, or that it had reproduced but the offspring on the plate had not reached at least the L2 stage. If a worm that was held over in one generation had not reproduced by the next generation, it was scored as a failure, and the worm was replaced with a worm from the backup generation. In the "N2" and "PB306" worksheets, in the last ten columns (IQ-IZ) , the column headings are labeled, in order, "Nhold", "Nback", "Ntotal", "Nfail", "Ncorrtotal", "N gens in Notes", "Gmax-Ncorr", "Discrepancy_corr", "%back" and "Best Estimate". Nhold and Nback are as above. Ntotal is the sum of Nhold and Nback. Nfail is as above. Ncorrtotal is the difference between Ntotal and Nfail ("corr" indicates "corrected"). "N gens in Notes" is the number of bottlenecks recorded in what was the data notebook of record at the conclusion of the experiment. However (see Methods), there is some uncertainty about this number, because one data notebook was lost (prior to G60) and some backups and holdovers went unrecorded. The MA bottlenecking protocol was interrupted at Gmax=194 to cryopreserve and ship worms from Indiana to Florida. Gmax-Ncorr is the difference between Gmax (194+50 generations of MA following the move = 244 gens) - Ncorr. Discrepancy_corr is the difference between Gmax-Ncorr and N gens in Notes. %back is = 1-Nhold/Ncorrtotal. The Best Estimate (of the actual # of MA generations) is N gens in Notes - %back*Discrepancy_corr.
Code/software
Microsoft Excel (or other software to read a .xlsx file).