Sampling locations of wolves (small open circles) and wolf-dog hybrids (black triangles 1–8, see also <b>Table 1</b>) in Estonia (Taebla) and Latvia (Dikli), hunted during the winter period of 2008–2009.

<p>The approximate ranges of wolves are with dark green (Estonia) and light green (Latvia).</p

First-generation (F1) wolf-dog hybrids from Wildlife Park Kadzidlowo, Poland: female wolf×male Polish Spaniel (left); female wolf×West Siberian Laika (right) (photos: A. Krzywinski).

<p>First-generation (F1) wolf-dog hybrids from Wildlife Park Kadzidlowo, Poland: female wolf×male Polish Spaniel (left); female wolf×West Siberian Laika (right) (photos: A. Krzywinski).</p

Bayesian phylogenetic tree of wolves, dogs and wolf-dog hybrids (from this study and homologous sequences from GenBank) based on the analysis of mtDNA control region sequences (1134 bp).

<p>Nodes with posterior probability values ≥0.80 are shown. Colours: green – dogs, blue – wolves, red – hybrids. Haplotypes representing more than one individual are numbered (circles 1–15). More detailed information about different haplotypes can be found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046465#pone.0046465.s004" target="_blank">Table S3</a>.</p

Bayesian analysis of wolf, dog and wolf-dog hybrid genotypes from Estonia and Latvia with the ‘parameter set A’ (<b>Table 2</b>).

<p>Analysis was based on 11 autosomal microsatellite loci using Structure v2.2, with the following parameters: <i>K</i> = 2 clusters; ‘Usepopinfo’ = 0 for all individuals (n = 103). Each vertical bar represents the membership coefficient (<i>q</i>) for each individual. The final eight bars on the right represent hybrids from Estonia (Ehy 1–6) and Latvia (Lhy 1–2).</p

Filial generation status of wolf-dog hybrids from Estonia and Latvia, estimated with Structure v2.2 under different combinations of ‘Usepopinfo’ parameter settings.

<p>Parameter set – two different ‘Usepopoinfo’ parameter sets (A, B) applied to the same data (n = 103). 0 – ‘Usepopinfo’ set to 0; 1 - ‘Usepopinfo’ set to 1; Ehy – hybrids from Estonia (n = 6); Lhy – hybrids from Latvia (n = 2). The q values (membership coefficient) indicate the probability of individual genotypes to belong to wolf cluster (in parentehesis 90% credible regions).</p

Median joining network of paternal lineages, based on analysis of seven Y chromosome microsatellite loci, showing male wolves, dogs and wolf-dog hybrids.

<p>Colours: green – dogs, blue – wolves, red – hybrids. W – wolf, D – dog, Ehy – hybrids from Estonia.</p

Median joining network of maternal lineages, based on mtDNA control region sequences (1134 bp), showing wolves, dogs and wolf-dog hybrids.

<p>Colours: green – dogs, blue – wolves, red – hybrids. W – wolf, D – dog, Ehy (1–6) – six hybrids from Estonia, Lhy (1–2) – two hybrids from Latvia. Numbers of individuals are in parentheses (if more than one individual is represented by the haplotype). Filled circles represent median vectors (haplotypes not sampled or extinct). Short bars indicate single mutations; otherwise the number of mutations is presented (note that the number of mutations and the length of bars are not in proportion).</p

Geographical ranges of four genetic groups (A–D) in the Estonian-Latvian wolf population based on distance weighted interpolation of Structure membership coefficients.

<p>As determined by 1000 bootstrap permutations the dark coloured grid points (5×5 km) denote group core areas. Individuals are represented by multi-coloured pies which reflect the membership coefficient for each cluster (zoom to see the details).</p

Spatial distribution of genetic differentiation between individuals in the Estonian-Latvian wolf population (n = 166) based on results of the spatially explicit DResD procedure at three spatial scales: (a-c) - the average D_LR-index (based on 16 microsatellite loci) between sample pairs, corrected for isolation by distance and interpolated across the study area using inverse distance weighting.

<p>The full coloured areas represent the 5 km grid points where the tested value deviates significantly from the null-model (IBD alone – a value of 0; p ≤0.05 according to 1000 iterations). The dots represent sample locations, and dashes denote locations and directions of sample pair midpoints lying at a particular distance range; the black section of the scale-bar in the top-left corner of each image represents the distance range of sample pairs included in the respective calculation.</p

Schematic representation of DResD results (shown in Figure 5).

<p>Migration directions and strength were determined with BayesAss (see Information S2), with dark green arrows indicating stronger and light green arrow weaker dispersal strength. Red prohibiting signs designate migration barriers (note that the barrier in the form of the Gulf of Riga was clearly identified by the analysis, whereas the city of Riga and its surrounding infrastructure are proposed to explain the evidence for a barrier in that approximate location). CoZ: contact zones for genetically distant individuals.</p