## 3 Results  
The results from the genetic diversity analyses showed that the mean number of alleles per locus varied between 7.08 and 9.90, where Sweden North had the lowest number of alleles and Hedmark South had the highest number. Hedmark South also had the highest mean number of private alleles (0.71), whilst Sweden South had the lowest number of private alleles (0.34). Allelic richness varied from 6.67 to 5.73, with Hedmark South exhibiting the highest values and Sweden South exhibiting the lowest. Sweden South exhibited the lowest inbreeding coefficient (\(F_{\rm IS}\)) with a value of 0.07, while the highest inbreeding coefficient was in Hedmark South with a value of 0.09 (Supplementary Table S2). When testing the genetic differentiation among the four study areas, the pairwise genetic distance (\(F_{\text{ST}}\)) ranged from 0.008 to 0.208. Out of the six pairwise combinations, five pairwise comparisons were significantly differentiated. The two Swedish study areas were significantly differentiated from the two Norwegian study areas, as well as being significantly differentiated from each other. However, the two Norwegian study areas did not exhibit significant differences in \(F_{\text{ST}}\) (Table 2). The population genetic analysis revealed that the most likely number of clusters estimated by Structure and Structure Harvester was two (K = 2, Figure S2). Assigned clusters indicated that the first cluster consisted of the two Norwegian study areas, as well as the Sweden North study area. The Sweden South study area was assigned to a separate cluster. No further sub-structuring was found when removing the Sweden South study area and re-running Structure (Figure 2). The neighbor-joining tree exhibited a main divide with moderately well-supported bootstrap values (0.67) into two separate branches, where the first branch consisted of the two Swedish study areas, and the second branch consisted of the two Norwegian study areas (Figure 2). [PERSON] reached a different conclusion regarding the number of population genetic clusters as it inferred the most likely number of clusters to be 1. The individual red foxes were spread across the geographical landscape, though they were still assigned to the same genetic cluster (Supplementary Figure S1). All individuals were assigned to a cluster, and there was no evidence of ghost clusters (i.e., clusters that contained no individuals). The historical gene flow analysis resulted in almost identical \(\Theta\) values for the two Swedish and the two Norwegian study areas. \(\Theta\) values were calculated to be the following: Hedmark South and Hedmark North = 0.098, Sweden North and Sweden South = 0.097. In total, only one of the comparisons of historic migration rates were significantly different based on 95% confidence intervals. The only significant difference in migration rate was found between Hedmark North and Sweden \begin{table}
\begin{tabular}{c c c c} \hline \hline \(F_{\text{st}}\) & **Hedmark N.** & **Sweden N.** & **Sweden S.** \\ \hline Hedmark S. & 0.208 & **0.008** & **0.008** \\ Hedmark N. & & **0.008** & **0.008** \\ Sweden N. & & & **0.008** \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Pairwise comparisons of genetic distance (\(F_{\text{ST}}\)) among the four study areas of red foxes. Significant differentiation after adjustment for multiple comparisons is marked in bold. Figure 2: Left: Neighbor-joining tree for the 4 study areas of sampled red foxes with bootstrap given on the axes. Right: Population genetic analyses of the four study areas of red foxes from Norway and Sweden analyzed for 24 microsatellites with results from STRUCTURE. An initial run suggested K = 2 genetic clusters in the total material. Hierarchical clustering suggested no further structure. North, with a significantly higher migration from the Norwegian to the Swedish study area. In more detail, the rate was highest from Hedmark North to Sweden North with values of M = 115 (CI: 95-137). From Sweden North to Hedmark North, the rate was M = 38.4 (CI: 19.3-55.3).