Data for: Assortative mating in an ecological context: Effects of mate choice errors and relative species abundance on the frequency and asymmetry of hybridization

The frequency and asymmetry of mixed-species mating set the initial stage
for the ecological and evolutionary implications of hybridization. How
such patterns of mixed-species mating, in turn, are influenced by the
combination of mate choice errors and relative species abundance remain
largely unknown. We develop a mathematical model that generates
predictions for how relative species abundances and mate choice errors
affect hybridization patterns. When mate choice errors are small
(<5%) the highest frequency of hybridization occurs when one of the
hybridizing species is at low abundance, but when mate choice errors are
high (>5%) the highest hybridization frequency occurs when species
occur in equal proportions. Furthermore, females of the less abundant
species are overrepresented in mixed-species matings. We compare our
theoretical predictions with empirical data on naturally hybridizing
Ficedula flycatchers and find that hybridization is highest when the two
species occur in equal abundance, implying rather high mate choice errors.
We discuss ecological and evolutionary implications of our findings and
encourage future work on hybrid zone dynamics that take demographic
aspects, such as relative species abundance, into account.