Insight into the genetic population structure of wild red foxes in Poland reveals low risk of genetic introgression from escaped farm red foxes

In this study we assessed the level of genetic introgression between red
foxes bred on fur farms in Poland and the native wild population. We also
evaluated the impact of a geographic barrier and isolation by distance on
gene flow between two isolated subpopulations of the native red fox and
their genetic differentiation. Nuclear and mitochondrial DNA was collected
from a total of 308 individuals (200 farm and 108 wild red foxes) to study
non-native allele flow from farm into wild red fox populations. Genetic
structure analyses performed using 24 autosomal microsatellites showed two
genetic clusters as being the most probable number of distinct
populations. No strong admixture signals between farm and wild red foxes
were detected, and significant genetic differentiation was identified
between the two groups. This was also apparent from the mtDNA analysis.
None of the concatenated haplotypes detected in farm foxes was found in
wild animals. The consequence of this was that the haplotype network
displayed two genetically distinct groups: farm foxes were completely
separated from native ones. Neither the River Vistula nor isolation by
distance had a significant impact on gene flow between the separated wild
red fox subpopulations. The results of our research indicate a low
probability of genetic introgression between farm and native red foxes,
and no threat to the genetic integrity of this species.