Introgression of mountain hare (Lepus timidus) mitochondrial DNA into wild brown hares (Lepus europaeus) in Denmark

Abstract

Background: In Europe the mountain hare (Lepus timidus) exists in Great Britain, Norway, Sweden, Finland, parts of the Alps and in Eastern Europe, but not in Denmark. Interspecific hybridization has been demonstrated between native Swedish mountain hares and introduced brown hares (Lepus europaeus). During the data collection in a study concerning Danish brown hares we identified 16 hares with a single very divergent haplotype.

Results: Phylogenetic analysis shows that the divergent Danish haplotype is most closely related to the Swedish mountain hare. The frequency of Lepus timidus mtDNA haplotype in the Eastern Danish hare populations is estimated to 6%.

Conclusion: In contrast to what is known, the Danish hare populations are not pure L. europaeus populations but include introgressed brown hares with Swedish L. timidus mtDNA. The most probable explanation of this is natural migration or translocation of introgressed brown hares from Sweden. The impurity of hare populations has implications for conservation and population genetics.

Figure 1

Location and frequency of the Lepus timidus haplotype in Denmark. Lepus timidus was found in five (large map) of the eight (small map) sampling locations.

Figure 2

Bayesian phylogeny of 370 bp from the mitochondrial D-loop of 20 Lepus timidus and 28 Lepus europaeus haplotypes from Europe, including the 19 Danish Lepus europaeus haplotypes, and the divergent Danish haplotype. The numbers show nodal support, given as posterior probabilities (for selected nodes, posterior probabilities from three independent runs are shown).