Data from: Genetic architecture of traits associated with reproductive barriers in Silene: coupling, sex chromosomes and variation

The evolution of reproductive barriers and their underlying genetic
architecture is of central importance for the formation of new species.
Reproductive barriers can be controlled either by few large-effect loci
suggesting strong selection on key traits, or by many small-effect loci,
consistent with gradual divergence or with selection on polygenic or
multiple traits. Genetic coupling between reproductive barrier loci
further promotes divergence, particularly divergence with ongoing gene
flow. In this study, we investigated the genetic architectures of ten
morphological, phenological and life history traits associated with
reproductive barriers between the hybridizing sister species Silene dioica
and S. latifolia; both are dioecious with XY sex determination. We used
quantitative trait locus (QTL) mapping in two reciprocal F2 crosses. One
to six QTLs per trait, including 9 major QTLs (PVE > 20%) were
detected, in total, on 11 of 12 linkage groups. We found strong evidence
for coupling of QTLs for uncorrelated traits. QTL clusters occurred both
on autosomes and on the sex chromosomes. Unexpectedly, QTLs detected in
the two F2 crosses differed largely, despite limited phenotypic
differences between them and sufficient statistical power. The widely
dispersed genetic architectures of traits associated with reproductive
barriers suggest gradual divergence or multifarious selection and coupling
of the underlying QTLs likely promoted divergence with gene flow in this
system. The low congruence of QTLs between the two crosses further points
to variable and possibly redundant genetic architectures of traits
associated with reproductive barriers, with important implications for the
evolutionary dynamics of divergence and speciation.