Data from: Detecting slow introgression of invasive alleles in an extensively restocked game bird

Interbreeding of two species in the wild implies introgression of alleles
from one species into the other only when admixed individuals survive and
successfully backcross with the parental species. Consequently, estimating
the proportion of first generation hybrids in a population may not inform
about the evolutionary impact of hybridization. Samples obtained over a
long time span may offer a more accurate view of the spreading of
introgressed alleles in a species’ gene pool. Common quail (Coturnix
coturnix) populations in Europe have been restocked extensively with farm
quails of hybrid origin (crosses with Japanese quails, C. japonica). We
genetically monitored a common quail population over 15 years to
investigate whether genetic introgression is occurring and used
simulations to investigate our power to detect it. Our results revealed
that some introgression has occurred, but we did not observe a significant
increase over time in the proportion of admixed individuals. However,
simulations showed that the degree of admixture may be larger than
anticipated due to the limited power of analyses over a short time span,
and that observed data was compatible with a low rate of introgression,
probably resulting from reduced fitness of admixed individuals.
Simulations predicted this could result in extensive admixture in the near
future.