DOI: 10.5061/dryad.16ff6
title: Data from: Coevolutionary interactions with parasites constrain the spread of self-fertilization into outcrossing host populations

description: Given the cost of sex, outcrossing populations should be susceptible to
 invasion and replacement by self-fertilization or parthenogenesis.
 However, biparental sex is common in nature, suggesting that
 cross-fertilization has substantial short-term benefits. The Red Queen
 hypothesis (RQH) suggests that coevolution with parasites can generate
 persistent selection favoring both recombination and outcrossing in host
 populations. We tested the prediction that coevolving parasites can
 constrain the spread of self-fertilization relative to outcrossing. We
 introduced wild-type Caenorhabditis elegans hermaphrodites, capable of
 both self-fertilization, and outcrossing, into C. elegans populations that
 were fixed for a mutant allele conferring obligate outcrossing. Replicate
 C. elegans populations were exposed to the parasite Serratia marcescens
 for 33 generations under three treatments: a control (avirulent) parasite
 treatment, a fixed (nonevolving) parasite treatment, and a copassaged
 (potentially coevolving) parasite treatment. Self-fertilization rapidly
 invaded C. elegans host populations in the control and the fixed-parasite
 treatments, but remained rare throughout the entire experiment in the
 copassaged treatment. Further, the frequency of the wild-type allele
 (which permits selfing) was strongly positively correlated with the
 frequency of self-fertilization across host populations at the end of the
 experiment. Hence, consistent with the RQH, coevolving parasites can limit
 the spread of self-fertilization in outcrossing populations.
description: Slowinski et al
 Evolution 2016 data DryadKey and description of
 the Slowinski et al. 2016 Evolution data submitted to Dryad Key:
 Treatments were abbreviated as follows: C: Control (heat-killed) parasite
 treatment F: Fixed-parasite (non-evolving parasite) treatment R: Recycled
 parasite treatment (referred to as the “copassaged” treatment in the
 paper) Genetic background data was abbreviated as follows: C: Lines that
 were previously passaged for 30 generations in a control, or heat-killed,
 parasite treatment prior to their use in the Slowinski et al. 2016
 Evolution study. E: Lines that were previously passaged in an “Evolution”
 treatment for 30 generations during which they were passaged on plates
 with a live but non-evolving parasite prior to their use in the Slowinski
 et al. 2016 Evolution study. F: Lines that were not previously subject to
 experimental evolution prior to the Slowinski et al 2016 Evolution study.
 The “F” genetic background lines are the ancestors of the “C” and “E”
 genetic background lines. OR is an abbreviation for outcrossing rate. SR
 is an abbreviation for selfing rate. MF is an abbreviation for male
 frequency. MMG is an abbreviation for mixed-mating genotype. Male
 frequencies sheet: The male frequencies data sheet contains the male
 frequency data from all the time points in the experiment in which male
 frequencies were measured. The generation 10, 15, 21, and 33 male
 frequencies were calculated by scoring the sexes of a random sample of 200
 individuals along a transect in experimental populations. The generation
 zero male frequencies were not measured directly, but rather were
 estimated based on the starting frequency of males in the mixed-mating
 populations (which are listed in the sheet called “mixed mating pop gen
 zero MFs”), and on the male frequencies in the obligately outcrossing
 generation zero populations (which were assumed to be 50% male and 50%
 female). The male frequencies at generations 10, 15, and 21 were all
 measured during the experiment in populations that had not been frozen and
 rethawed prior to male frequency measures. The male frequencies in
 generation 33 populations were measured before and after the populations
 had been frozen and rethawed, as indicated in the data sheet. Outcrossing
 rates data sheet: This sheet indicates the outcrossing rates for each of
 the experimental lines. Outcrossing rates were calculated from the male
 frequencies using the equation: outcrossing rate = (male frequency –
 0.0015) X 2 The 0.0015 in the equation is to correct for males produced by
 non-disjunction of the X chromosome during meiosis, which we assumed
 occurs at a frequency of 0.0015. Selfing rates data sheet: The selfing
 rates data sheet indicates the selfing rates for each experimental line at
 each of the time points measured. Selfing rates were calculated using the
 following equation: Selfing rate = 1 – Outcrossing rate Mixed mating pop
 gen zero MFs sheet: The Mixed mating pop gen zero MFs sheet indicates the
 male frequencies that we measured in the mixed mating populations shortly
 before the initiation of our experiment (i.e. these male frequencies were
 measured before the mixed-mating populations and the obligately
 outcrossing populations were combined). The male frequencies that we
 measured in the mixed-mating populations prior to the start of our
 experiment were used to estimate the male frequencies in the mixed
 (mixed-mating + obligately outcrossing) populations at the start
 (generation zero) of our experiment.