Figure legends
Figure 1. Different scenarios of the secondary contact outcomes in a host-parasite association. (a) the host re-establishes a panmictic population while the parasite differentiates into two separated species, which keep spreading and eventually live in sympatry.(b) both host and the parasite create hybrid zone; parasite’s hybrid zone is narrower. (c) the host re-establishes panmictic population while the parasite creates a narrow hybrid zone. (d)as a consequence of the scenario c, the host moves freely across the whole area but it experiences a “parasite turnover” when crossing the hybrid zone.
Figure 2 . Genetic background of Apodemus spp. andPolyplax serrata adopted from Martinů et al., 2018. (a)The main genetic pattern of Apodemus hosts relevant to this study. Inner mtDNA structure of A.sylvaticus is ignored since it is not relevant to the discussion of the secondary contact zone (see the text). (b) Geographic distribution of the hosts: both spp. co-occur across Europe with their intraspecific mtDNA clades randomly dispersed. Both spp. are parasitized by the non-specific lineage (N) of the lice shown on the d. (c) Two mtDNA lineages of A. flavicollis which in addition to the N lineage are parasitized by the specific lineage (S; depicted on d). SCZ: schematic representation of the presumed secondary contact zone of the two mtDNA lineages of both the A. flavicollis and the S lineage of the parasite. While the host‘s lineages dispersed across the whole Europe after glaciation, the parasite‘s lineages remain confined to the two exclusive areas (red and blue) with a narrow hybrid zone (the violet line). (d) The main genetic pattern of Polyplax serrata showing ecological complexity of this parasite: the N and S lineages live in sympatry but differ in the degree of host specificity (single host vs two hosts); the SW (specific west) and SE (specific east) lineages create a hybrid zone (the „parasite turnover zone“) which transverses panmictic population of the host.
Figure 3. (a) Distribution of the P. serrata S lineage samples analyzed in Martinů et al., (2018). (b) Detailed distribution of the samples used in this study. Blue and red designate the SW and SE sublineages, respectively.
Figure 4. Comparison of maternally inherited markers and nuclear SNPs. In all parts the two mitochondrial lineages are designated by different colours: blue=SW, red=SE, and the nuclear hybrids are identified by purple background. (a) phylogenetic tree based on complete genomes of L. polyplacis from 23 samples of P. serrata . (b) phylogenetic tree based on concatenated 11 minichromosomes of P. serrata . (c) PCA analysis of nuclear SNPs showing the pure parental clusters SW/SE and the hybrid cluster by the blue, red and purple background, respectively.(d) Admixture analysis of SNP data under K2 parameter recognizing the parental populations and hybrids.