Data from: Modeling and quantifying frequency-dependent fitness in microbial populations with cross-feeding interactions
Data files
Mar 12, 2015 version files 377.66 KB
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Fit competition data to FD_linear.nb
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Fit competition data to FD_quadratic.nb
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Monod model and fit to linear FD_black queen.nb
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Monod model and fit to linear FD_crossfeeding.nb
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nuoM_competition_data.csv
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README_for_Monod model and fit to linear FD_black queen.rtf
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README_for_Monod model and fit to linear FD_crossfeeding.rtf
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README_for_nuoM_competition_data.rtf
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README_for_S_L_competition_data.rtf
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S_L_competition_data.csv
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Abstract
Coexistence of two or more populations by frequency-dependent selection is common in nature, and it often arises even in well-mixed experiments with microbes. If ecology is to be incorporated into models of population genetics, then it is important to represent accurately the functional form of frequency-dependent interactions. However, measuring this functional form is problematic for traditional fitness assays, which assume a constant fitness difference between competitors over the course of an assay. Here, we present a theoretical framework for measuring the functional form of frequency-dependent fitness by accounting for changes in abundance and relative fitness during a competition assay. Using two examples of ecological coexistence that arose in a long-term evolution experiment with Escherichia coli, we illustrate accurate quantification of the functional form of frequency-dependent relative fitness. Using a Monod-type model of growth dynamics, we show that two ecotypes in a typical cross-feeding interaction—such as when one bacterial population uses a byproduct generated by another—yields relative fitness that is linear with relative frequency.