DOI: 10.5061/dryad.d7c40gn
title: Data from: The evolutionary response of mating system to heterosis

description: Isolation allows populations to diverge and to fix different alleles.
 Deleterious alleles that reach locally high frequencies contribute to
 genetic load, especially in inbred or selfing populations, in which
 selection is relaxed. In the event of secondary contact, the recessive
 portion of the genetic load is masked in the hybrid offspring, producing
 heterosis. This advantage, only attainable through outcrossing, should
 favor evolution of greater outcrossing even if inbreeding depression has
 been purged from the contributing populations. Why, then, are
 selfing-to-outcrossing transitions not more common? To evaluate the
 evolutionary response of mating system to heterosis, we model two
 monomorphic populations of entirely selfing individuals, introduce a
 modifier allele that increases the rate of outcrossing, and investigate
 whether the heterosis among populations is sufficient for the modifier to
 invade and fix. We find that the outcrossing mutation invades for many
 parameter choices, but it rarely fixes unless populations harbor extremely
 large unique fixed genetic loads. Reversions to outcrossing become more
 likely as the load becomes more polygenic, or when the modifier appears on
 a rare background, such as by dispersal of an outcrossing genotype into a
 selfing population. More often, the outcrossing mutation instead rises to
 moderate frequency, which allows recombination in hybrids to produce
 superior haplotypes that can spread without the mutation's further
 assistance. The transience of heterosis can therefore explain why
 secondary contact does not commonly yield selfing-to-outcrossing
 transitions.
description: Focal
 scenarioThese data are the
 simulated fixation proportions for the focal scenario. Rows represent the
 selection coefficient. Columns represent the number of fixed deleterious
 alleles per population.focal.zipGenotype frequency trajectoriesThese data represent the distribution of genotypes at the outcrossing modifier locus over time. The first column represents the frequency of mm, the second column represents the frequency of Mm, and the third column represents the frequency of MM. Each row represents a generation. NAs represent untracked generations after fixation has already occurred.trajectories.zipUnequal fitnessThese data represent fixation proportions for scenarios in which the two parental populations have unequal fitnesses.unfair_data.zipUnequal sizeThese data represent fixation proportions when the two parental populations contribute unequally to the daughter population. Columns represent number of fixed deleterious alleles per population, and rows represent the initial frequency of the ancestral genotype on which the outcrossing mutation arose.asymmetric_data_coefficientUnpurged inbreeding depressionThese data represent trials used to determine the effect of initial unpurged inbreeding depression in the parental populations. Each file contains a fixation proportion, designates whether there was initial inbreeding depression or not, and designates how many additional fixed sites per population there were.initial_depression.zipTrajectories with inbreeding depression trackedContains population trajectories in which average fitness, maximum fitness, inbreeding depression, and modifier genotype frequencies are tracked through time. Except for inbreeding depression, each trajectory is a three-column matrix in which each column represents a modifier-locus genotype (e.g., average fitness of individuals with genotype Mm). Each row is a generation. Inbreeding depression is vector of the population's inbreeding depression through time.depression_trajectories.zip