North-South Differentiation and a Region of High Diversity in European Wolves (Canis lupus)

Abstract

European wolves (Canis lupus) show population genetic structure in the absence of geographic barriers, and across relatively short distances for this highly mobile species. Additional information on the location of and divergence between population clusters is required, particularly because wolves are currently recolonizing parts of Europe. We evaluated genetic structure in 177 wolves from 11 countries using over 67K single nucleotide polymorphism (SNP) loci. The results supported previous findings of an isolated Italian population with lower genetic diversity than that observed across other areas of Europe. Wolves from the remaining countries were primarily structured in a north-south axis, with Croatia, Bulgaria, and Greece (Dinaric-Balkan) differentiated from northcentral wolves that included individuals from Finland, Latvia, Belarus, Poland and Russia. Carpathian Mountain wolves in central Europe had genotypes intermediate between those identified in northcentral Europe and the Dinaric-Balkan cluster. Overall, individual genotypes from northcentral Europe suggested high levels of admixture. We observed high diversity within Belarus, with wolves from western and northern Belarus representing the two most differentiated groups within northcentral Europe. Our results support the presence of at least three major clusters (Italy, Carpathians, Dinaric-Balkan) in southern and central Europe. Individuals from Croatia also appeared differentiated from wolves in Greece and Bulgaria. Expansion from glacial refugia, adaptation to local environments, and human-related factors such as landscape fragmentation and frequent killing of wolves in some areas may have contributed to the observed patterns. Our findings can help inform conservation management of these apex predators and the ecosystems of which they are part.

Combining phylogenetic and demographic inferences to assess the origin of the genetic diversity in an isolated wolf population

“…Results indicate that the main geographical populations in central and southern Europe are genetically distinct. The Italian and the Iberian wolves were the first ones to cluster separately in both multivariate and Bayesian clustering, confirming Lucchini et al [13], Stronen et al [52], and Pilot et al [16]. Wolves sampled from populations in the eastern countries, and particularily from the Balkan and Carpathian regions show signatures of admixture, supporting previous mtDNA and autosomal SNP findings [16,52].…”

“…Samples from WBALK, WCARP and WBALT were not used in the simulations because these populations are still in connection one another and also with unsampled wolf populations in eastern Europe [51,52]. …”

Genome-wide signatures of population bottlenecks and diversifying selection in European wolves

“…We also used ADMIXTURE to carry out a separate analysis for Eastern European wolves only. We performed this additional analysis because earlier studies suggested population structuring in this region (Pilot et al, 2006;Stronen et al, 2013), which could have remained undetected in the context of strongly differentiated wolf populations from other parts of the world.…”

“…In Eastern Europe, there are large and interconnected populations (Figure 1), most of which have experienced constant hunting pressures. Cryptic population structure has been observed in Eastern Europe (Pilot et al, 2006;Stronen et al, 2013), but this genetic differentiation is small compared to the differentiation between Eastern Europe and both Italian and Iberian populations. Therefore, herein, we use the term 'Eastern European population' despite the lack of panmixia.…”

Wolf population genetics at the south-eastern edge of their European range

“…Despite partially recovering from heavy poaching and the use of poisoned baits, wolves in Greece are still threatened by human-caused mortality, limited food availability and on-going habitat destruction and fragmentation (Iliopoulos, 2009). Although belonging genetically to the wider Dinaric-Balkan population (Stronen et al, 2013), genetic structure of a population at the edge of its range, such as the wolf population in Greece, may vary at a smaller, local scale (Yannic et al, 2012) and lower genetic variation may occur after recent population recovery events (Excoffier et al, 2009). The aim of this study was to evaluate the population structure, genetic diversity and population history of wolves in Greece and identify conservation priorities for the species in the country.…”