Recent hybrids recapitulate ancient hybrid outcomes

Genomic outcomes of hybridization depend on selection and recombination in
hybrids. Whether these processes have similar effects on hybrid genome
composition in contemporary hybrid zones versus ancient hybrid lineages is
unknown. Here we show that patterns of introgression in a contemporary
hybrid zone in Lycaeides butterflies predict patterns of ancestry in
geographically adjacent, older hybrid populations. We find a particularly
striking lack of ancestry from one of the hybridizing taxa, Lycaeides
melissa, on the Z chromosome in both the old and contemporary hybrids. The
same pattern of reduced L. melissa ancestry on the Z chromosome is seen in
two other ancient hybrid lineages. More generally, we find that patterns
of ancestry in old or ancient hybrids are remarkably predictable from
contemporary hybrids, which suggests selection and recombination affect
hybrid genomes in a similar way across disparate time scales and during
distinct stages of speciation and species breakdown.