Does prey scarcity increase the risk of wolf attacks on domestic dogs?

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Wolves Recolonizing Islands: Genetic Consequences and Implications for Conservation and Management.

After a long and deliberate persecution, the grey wolf (Canis lupus) is slowly recolonizing its former areas in Europe, and the genetic consequences of this process are of particular interest. Wolves, though present in mainland Estonia for a long time, have only recently started to recolonize the country's two largest islands, Saaremaa and Hiiumaa. The main objective of this study was to analyse wolf population structure and processes in Estonia, with particular attention to the recolonization of islands. Fifteen microsatellite loci were genotyped for 185 individuals across Estonia. As a methodological novelty, all putative wolf-dog hybrids were identified and removed (n = 17) from the dataset beforehand to avoid interference of dog alleles in wolf population analysis. After the preliminary filtering, our final dataset comprised of 168 "pure" wolves. We recommend using hybrid-removal step as a standard precautionary procedure not only for wolf population studies, but also for other taxa prone to hybridization. STRUCTURE indicated four genetic groups in Estonia. Spatially explicit DResD analysis identified two areas, one of them on Saaremaa island and the other in southwestern Estonia, where neighbouring individuals were genetically more similar than expected from an isolation-by-distance null model. Three blending areas and two contrasting transition zones were identified in central Estonia, where the sampled individuals exhibited strong local differentiation over relatively short distance. Wolves on the largest Estonian islands are part of human-wildlife conflict due to livestock depredation. Negative public attitude, especially on Saaremaa where sheep herding is widespread, poses a significant threat for island wolves. To maintain the long-term viability of the wolf population on Estonian islands, not only wolf hunting quota should be targeted with extreme care, but effective measures should be applied to avoid inbreeding and minimize conflicts with local communities and stakeholders

Principal component analysis (PCA) of Estonian wolves (n = 168) representing four genetic groups (G1–G4) as suggested by STRUCTURE.

<p>Points represent individual genotypes; genetic groups are labelled inside their 95% inertia ellipses. Note that only individuals with a membership coefficient <i>q</i> > 0.7 are shown. Inset figure shows a bar chart of the eigenvalues with corresponding components filled in black.</p

Spatial distribution of local average heterozygosity in Estonian wolf population.

<p>Based on the proportion of heterozygous loci at individual level, statistically interpolated across the study area using procedure of universal kriging. The full colored areas represents statistically significant deviation from global median (0.67); <i>p</i> ≤ 0.05 according to 499 bootstrap iterations. The dots represent sample locations.</p

Spatial distribution of local genetic differentiation in the Estonian wolf population.

<p>In the DResD analysis, neighbouring individual pairs are used in distance range 17–33 km. The pairwise IBD corrected genetic distance (Nei’s D) was interpolated across the study area using the procedure of universal kriging. The full coloured areas represent statistically significant deviation from the global model of IBD; <i>p</i> ≤ 0.05 according to 499 bootstrap iterations; median IBD residual = 0.12. The large points represent sample locations and the small dots denote midpoint locations of sample pairs.</p

Locations of four genetic groups in the Estonian wolf population (n = 168) according to STRUCTURE (admixture model; 15 autosomal microsatellite loci).

<p>Colored dots denote the sample locations and groups are colored as follows: G1 (green), G2 (blue), G3 (red), and G4 (yellow). Individuals are placed into a particular genetic group based on their highest membership coefficient. The background map was downloaded from an Open Access database of the Estonian Land Board (<a href="http://www.maaamet.ee" target="_blank">www.maaamet.ee</a>; download date: 1. Nov. 2014).</p

Changes in numbers of wolf packs and hunted wolves in Estonia during the last fifteen years (2000–2014; data from the Estonian Environment Agency).

<p>Inset figure represents the age structure of analysed wolves (n = 138, the age estimation was not available for all wolves) during the hunting seasons of 2011–2012 to 2014–2015 in Estonia.</p

Putative elements of the genetic structure and dynamics in Estonian wolf population during 2011–2015.

<p>The conclusion is based on the analysis of placement of genetic groups (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158911#pone.0158911.g002" target="_blank">Fig 2</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158911#pone.0158911.s002" target="_blank">S2 Fig</a>), DResD (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158911#pone.0158911.g004" target="_blank">Fig 4</a>), and heterozygosity distribution (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158911#pone.0158911.g005" target="_blank">Fig 5</a>). The dots represent sample locations.</p