Data from: Variable hybridization outcomes in trout are predicted by historical fish stocking and environmental context

Hybridization can profoundly affect the genomic composition and phenotypes
of closely related species, and provides an opportunity to identify
mechanisms that maintain reproductive isolation between species. Recent
evidence suggests that hybridization outcomes within a species pair can
vary across locations. However, we still don't know how extensive
variation in outcomes of hybridization is across geographic replicates,
and what mechanisms drive that variation. In this study, we described
hybridization outcomes across 27 locations in the North Fork Shoshone
River basin (Wyoming, USA) where native Yellowstone cutthroat trout and
introduced rainbow trout co-occur. We used genomic data and hierarchical
Bayesian models to precisely identify ancestry of hybrid individuals.
Hybridization outcomes varied across locations. In some locations, only
advanced backcrossed hybrids towards rainbow trout and pure rainbow trout
were present, while other locations had a broader range of individuals,
including both parental species and first-generation hybrids. Using an
individual-based simulation, we found that outcomes of hybridization in
the North Fork Shoshone River basin deviate substantially from what we
would expect under assumptions of random mating and no selection against
hybrids. Since this implies that some mechanisms of reproductive isolation
function to maintain parental taxa and a diversity of hybrid types, we
then modeled hybridization outcomes as a function of environmental
variables and stocking history that are likely to affect prezygotic
barriers to hybridization. Variables associated with history of fish
stocking were the strongest predictors of hybridization outcomes, followed
by environmental variables that might affect overlap in spawning time and
location.