DOI: 10.5061/dryad.73n5tb2vq
title: The evolution of sex is tempered by costly hybridization in Boechera (rock cress)

description: Despite decades of research, the evolution of sex remains an enigma in
 evolutionary biology. Typically, research addresses the costs of sex and
 asexuality to characterize the circumstances favoring one reproductive
 mode. Surprisingly few studies address the influence of common traits that
 are, in many organisms, obligately correlated with asexuality, including
 hybridization and polyploidy. These traits have substantial impacts on
 traits under selection. In particular, the fitness consequences of
 hybridization (that is, reduced fitness due to interspecific reproductive
 isolation) will influence the evolution of sex. This may comprise a cost
 of either sex or asexuality, due to the link between hybridity and
 asexuality. We examined reproductive isolation in the formation of de novo
 hybrid lineages between two widespread species in the ecological model
 system Boechera. 17% of 664 crosses produced F1 fruits, and only 10% of
 these were viable, suggesting that postmating prezygotic and postzygotic
 barriers inhibit hybrid success in this system. The postmating prezygotic
 barrier was asymmetrical, with 110 of 115 total F1 fruits produced when B.
 stricta acted as maternal parent. This asymmetry was confirmed in
 wild-collected lineages, using a chloroplast phylogeny of wild-collected
 B. stricta, B. retrofracta, and hybrids. We next compared fitness of F2
 hybrids and selfed parental B. stricta lines, finding that F2 fitness was
 reduced by substantial hybrid sterility. Multiple reproductively isolating
 barriers likely influence the formation and fitness of hybrid lineages in
 the wild, and the costs of hybridization likely have profound impacts on
 the evolution of sex in the natural environment.
description: Three datasets are included in this submission, and each was
 collected in the greenhouse. The first ("F1success_data.csv") is
 a dataset collected in the greenhouse that contains information on the
 identity of a given cross and whether or not crossed flowers developed
 into fruits and successfully set seed. The second
 ("F1germination_data.csv") is another greenhouse-collected
 dataset that contains information on each individual fruit produced, and
 germination rate, viability, and sterility for each. Columns in both
 datasets that start with the prefix "Prop" are proportions
 that were calculated according to the README document. The third dataset
 ("Greenhouseexpt_data.csv") was collected during a greenhouse
 experiment on F2 plants. Average seed set for a given genotype was
 calculated as in Rushworth et al. 2019 (https://doi.org/10.1101/719252). No processing was conducted.<br> <br> One final file provided is a Nexus file used to create the chloroplast tree. New sequences generated in this publication have been submitted in Genbank (Genbank #s MW052148 - MW052220).
description: Missing values are indicated by X, NA, or blank spaces. All
 headers from datasets are explained in the README file. Analyses for all
 three datasets are in the R script. Please feel free to address any
 questions to the corresponding author.