Data from: The genomic trajectory of hybrid swarms: outcomes of repeated crosses between populations of Tigriopus californicus

Introgressive hybridization between genetically divergent populations is
an important evolutionary process. The degree to which repeated
hybridization events between the same parental taxa lead to similar
genomic outcomes is unknown. This study addressed this question by
following genomic trajectories of replicate hybrid swarms of the copepod
Tigriopus californicus over many generations of free mating. Swarm
composition was determined both by differential reproductive success of
founder individuals and subsequent selection on hybrid genotypes. For one
cross, between two populations showing differential fitness in the
laboratory and no hybrid breakdown, the genetic trajectory was highly
repeatable: replicates rapidly became dominated by alleles from the fitter
parent. In a second cross, between two populations showing similar fitness
and significant F2 hybrid breakdown, alleles from alternative populations
dominated different replicates. Swarms exhibited a general temporal trend
of decreasing cytonuclear mismatch. Some patterns of differential
introgression across the genome were strikingly congruent amongst swarm
replicates, both within and between cross types, and reflected patterns of
segregation distortion previously observed within controlled crosses
between the same parental populations. Differences in heterozygosity
between the sexes, and evidence for a previously suspected sex-distortion
locus, suggest that complex interactions between sex and genotype
influence hybrid swarm outcome.